Episode 23: ThunderKAT

with Prof Patrick Woudt

In Episode 23 of The Cosmic Savannah podcast, we are joined by the Head of Astronomy at the University of Cape Town, Professor Patrick Woudt.

Prof Woudt joins us to talk about an exciting project he is involved in using the MeerKAT radio telescope, namely ThunderKAT (The HUNt for Dynamic and Explosive Radio transients with meerKAT). ThunderKAT is looking for explosive things that flash in the radio sky!

The project has recently observed a black hole ejecting material at close to the speed of light out to some of the largest angular distances (separations) ever seen. These observations have allowed a deeper understanding of how black holes feed into their environment

Featured Guest

Featured Image:
South Africa has already demonstrated its excellent science and engineering skills by designing and building the MeerKAT radio telescope – as a pathfinder to the SKA. The 64-antenna array is located at the SKA site at Losberg in the Karoo, about 90 kilometres from Carnarvon. Credit: SARAO (South African Radio Astronomy Observatory).

Related Links:
News article: https://www.news.uct.ac.za/article/-2020-03-02-shedding-new-light-on-black-hole-ejections
ThunderKAT: http://www.thunderkat.uct.ac.za/
MeerKAT: http://www.ska.ac.za/
MeerLICHT: http://meerlicht.uct.ac.za
SKA: http://www.skatelescope.org/

Transcript

(By Brandon Engelbrecht)

Jacinta: [00:00:00] Welcome to The Cosmic Savannah with Dr. Jacinta Delhaize 

Dan: [00:00:08] and Dr. Daniel Cunnama. Each episode, we’ll be giving you a behind the scenes look at the world-class astronomy and astrophysics happening under African skies. 

Jacinta: [00:00:17] Let us introduce you to the people involved, the technology we use, the exciting work we do and the fascinating discoveries we make.

Dan: [00:00:25] Sit back and relax as we take you on a Safari through the skies.

Jacinta: [00:00:32] Hello everyone. Welcome to episode 23. Dan is joining us from home via Skype. 

Dan: [00:00:38] Yeah. We’re all under lockdown. For the next little while, we’ll be having to do our recording via skype.

Jacinta: [00:00:44] Yeah, so of course, this is because of the coronavirus outbreak. South Africa has gone into lockdown now. Uh, like most of the world and we were considering whether or not to put out this episode weren’t we Dan?

Dan: [00:00:58] Yeah, but I think it’s, I think it’s good. I think that people are going to need some stuff to listen to and hopefully we can provide that. 

Jacinta: [00:01:05] Yeah, I hope so too. Um, we all want a distraction. We all want to, you know, talk about something different and learn something new. So why not go ahead with that.

We’ll just have to put up with some low-quality sound from Dan’s end for a little while, but I think it’s okay and I’ve taken the recording equipment back to my house and I’m literally sitting in a blanket fort, which I made for myself for soundproofing. 

Dan: Very professional.

Jacinta: Yes, definitely. I’m going to put a picture of it on the social media so you can have a look. I’m very proud of it. Right. Okay. So what are we talking about today, Dan? 

Dan: [00:01:40] So today we’re joined by Professor Patrick Woudt he is the Head of Astronomy at the University of Cape Town here in Cape Town and he’s also the principal investigator for the ThunderKAT project, which is a large science project on the MeerKAT telescope. 

Jacinta: [00:01:59] As we’ll talk about further when we chat to Patrick, the LSPs, as we call them, Large Science Projects are what MeerKAT is mostly going to be focused on during its run time and ThunderKAT is one of those.

It stands for The Hunt for Dynamic and Explosive Radio Transients with MeerKAT, if you can figure that one out,  how they got to that acronym.

Dan: Just another contrived acronym

Jacinta: Oh, astronomers love it. Okay and so this is a survey in the radio with MeerKAT to look for transients. 

Dan: [00:02:30] Yeah. So what is a transient?

Jacinta: [00:02:32] A transient is something that goes bang, basically an explosion, uh, in space. It’s something that wasn’t there before and then happens now. It is a transient event. So it happens sometimes and not at other times and one of these objects that ThunderKAT is going to be looking at is X-ray Binaries.

Dan:  And what is an X-ray Binary?

Jacinta: Well, we did talk a little bit about it in episode 21 I think with Tanya Joseph, she talked a lot about these X-ray binaries. A binary is two stars going around each other and often one of these stars is a compact object. A compact object is something like a white dwarf or a neutron star or a black hole, something that’s, the fossil of the end of a star’s life and often it means that this compact object is going to be sucking material off its companion star, which is still a big normal star with gas on it and as this happens, it can release X-rays and then it’s called an X-ray binary. 

Dan: [00:03:38] Yeah. So you’re basically looking at two stars, what was two stars orbiting around each other. One of them has now gone compact and the other one is just a regular star, right?

Jacinta: [00:03:48] Yeah, exactly and part of what ThunderKAT going to do is that they, there is several known X-ray binaries and there are X-ray telescopes looking at them and then MeerKAT is going to regularly look at the same binaries in the radio and check whether they’ve changed if they’re releasing more or less radio waves and then figure out what that means.

Dan: [00:04:09] And this is exactly what we’re gonna be talking about today right because they have already spotted one. 

Jacinta: [00:04:13] They have actually found a new one while they were looking at one of these transients that they already knew existed. They spotted a new one and they’ve got a paper out on that and they also found one of these transients that they were monitoring doing something new and crazy.

And so they’ve published that in Nature Astronomy, which is quite a prestigious journal. They found that this object was emitting X-rays, so there was accretion happening, which means that the compact object is sucking in gas from its companion star, but then they found something special happening in the radio data with MeerKAT in that it was releasing jets.

So like huge ejections of material of matter, electrons and stuff near the compact object and it was being thrown out into space in one of the most energetic processes ever seen for this kind of event and being thrown out to one of the largest distances. 

Dan: [00:05:09] Yes. I mean, it’s a very exciting discovery and great to see that these sorts of discoveries are already coming out of MeerKAT and some of the MeerKAT projects. 

I think that we should probably speak to Patrick, who will tell us about all about it and also about the couple of other things we spoke to them about, such as the UCT Astronomy Department’s 50 year anniversary and the MeerLICHT telescope that we have mentioned once before.

Uh, which is another one of these multi-wavelength, a collaboration between MeerKAT and in this case, an optical telescope.

Jacinta: [00:05:41] Yeah. Great. Let’s hear from Patrick

With us, in the studio today is Professor Patrick Woudt, who is the Head of Department for Astronomy at the University of Cape Town. Welcome, Patrick. 

Patrick: Hi Jacinta. 

Dan: [00:05:57] Welcome to The Cosmic Savannah. 

Patrick: [00:05:58] Hi Daniel. 

Jacinta: [00:06:00] So Patrick, you are actually my big boss, I guess. Tell us about yourself. 

Patrick: [00:06:06] I’ve been in South Africa for a long time. I did my PhD at the University of Cape Town, finished in ‘97 on large scale structures of galaxies under the supervision of Tony Fairall.

And I used many of the telescopes in Sutherland during that time. I went to ESO as a postdoc afterwards for two years and I came back to South Africa in 2000 and I’ve been here ever since, initially as a postdoctoral fellow and later as a senior lecturer, associate professor and now professor in the department.

Jacinta: [00:06:35] So you are from the Netherlands originally. But you’ve spent most of your career here in South Africa.

Patrick: [00:06:39] Indeed, yes. So I grew up in the Netherlands, did my first degree in The University of Groningen. Um, but then as I said,  in 95, I came to South Africa. 

Dan: [00:06:47] and you’re now the Head of the Astronomy Department, at UCT, right?

Patrick: [00:06:50] I am indeed. I’ve been for the last five years already. 

Jacinta: [00:06:54] And you also have another role. You are one of the PIs, the principal investigator, of the ThunderKAT project, which is an LSP and that’s a “large science project” for MeerKAT. So we know from our previous episodes that MeerKAT is a big radio telescope in the Karoo in South Africa and most of the time we’ll be doing observations for these LSPs.

So these were proposed many years ago and went through a rigorous selection committee and in several of the large projects were chosen probably taking what, hundreds or thousands of hours, each and a ThunderKAT was one of those. So tell us about ThunderKAT. You’re actually the first PI of an LSP that we’ve interviewed 

Patrick: [00:07:38] I’m honoured.

Jacinta: [00:07:40] So tell us about ThunderKAT 

Patrick: [00:07:41] ThunderKAT is a large program on MeerKAT, which aims to study the accretion, the mass transfer of gas from one star to another and these are very compact binaries. So they complete one binary orbit, for instance, in about an hour, an hour and a half. If you compared it to the Earth going around the Sun, in one year or here you’ve got two stars, one very compact, the size of the Earth, the other one maybe the size of the Sun, completing one binary orbit in an hour and a half.

So that means they are very close together and when they’re that close together, they transfer mass and sometimes at mass when it’s transferred onto the compact central star, the most massive star, very exciting things happen. You get sort of explosions that throw material back into the interstellar medium and that sort of outflow, that mass ejection you can study in the radio.

Dan: [00:08:32] In this situation with compact binaries, the compact object is the more massive of the two right? And the Sun-like object or star-like object, that’s the one that’s losing its mass and slowly getting devoured by the compact object. 

Jacinta: [00:08:49] Surely the compact object can’t be a normal star. If it’s the size of the Earth?

Patrick: [00:08:53] That’s right. So, so in my case, the objects that I study are the compact star is called what’s called a white dwarf, which is the end product of what our Sun eventually will become. But there are other compact stars like neutron stars and black holes, stellar-mass black holes that are even denser, more denser than the, than a white dwarf.

And so a neutron star has, has the mass of 1.4 times the mass of the Sun, but it’s the size of Cape Town, for instance, sort of 10 kilometres in size. 

Dan: [00:09:20] So we’ve spoken previously about X-ray binaries. So X-ray binaries are basically a subclass of these compact binaries. You can have a binary system with a white dwarf as you are studying and then as you just mentioned, a compact binary with a black hole or a neutron star which are even more compact and these white dwarf boundaries that you are studying, they’re obviously not visible in X-ray?

Patrick: [00:09:46] They do have X-ray emission, but, um, so the different wavelengths trace the different components of such a binary. So in the white dwarf accreting binaries, um, the ultraviolet is the proxy for mass transfer.

If the ultraviolet emission is very strong, the mass transfer is very high. The radio is the proxy for outflow from the system through various emission mechanisms. In neutron stars, the proxy for accretion is not the ultraviolet, but even higher energy emission mechanisms, which is the X-ray. So when you study X-ray binaries, so you want to study them in X-ray to study the accretion onto the neutron star and in radio to probe the outflow that’s been induced by that accretion. Some of that material, excess material then gets thrown off the system.

Jacinta: [00:10:34] Okay, so there’s a normal star and then there’s a compact object, like a black hole or a neutron star or a white dwarf and you’re saying that some of the, the outer layers of this big star is being drawn onto this small compact object.

Patrick: That’s right.

Jacinta: If we see X-rays coming from this system, if we can detect the object in X rays, then that means that it is undergoing this process of accretion. So where the outer layers are being pulled onto the compact object and if we see it in radio waves, then that’s telling us that there is this sort of outflow, these big ejections of, of matter shooting into space.

Is that right? 

Patrick: [00:11:13] That’s, that’s right. 

Dan: [00:11:13] So what is the mechanism for these outflows? You’re talking about mass falling onto a compact star. Why do we expect an outflow? 

Patrick: [00:11:21] Yeah, so there are different kinds of mechanisms in these binary systems, in the systems that I am most familiar with, the white dwarf accreting systems, you can have a cataclysmic outflow, which is a thermonuclear runaway on the surface of the white dwarf, which ejects the accreted material in an explosion and it blows it off at very high velocities, up to maybe a 10,000 kilometres per second, which is incredible; an incredible injection of energy. But they’re also more sedate ways of outflow and that, we haven’t talked about this yet, but the mass transfer from the companion star to a white dwarf normally goes through an accretion disk and sometimes that accretion disk gets into a higher state or hotter state, which allows the mass to flow more efficiently onto the white dwarf.

And you can have all sorts of wind mechanisms that blow material off. So you can have collimated winds creating an outflow. 

Jacinta: [00:12:13] Okay. So you can have a thermonuclear detonation of the white dwarf, or you can have the star’s layers being pulled towards the compact object and in a disk sort of like a dinner plate shape, right?

Going around this compact object and then sort of trickling onto the compact object, right? 

Patrick: [00:12:32] That’s correct

Dan: [00:12:33] So this isn’t happening all of the time right? These things are gonna have these little explosions, these outflows and then they’re going to disappear. 

Patrick: [00:12:39] Yeah. So, so these binaries, they exist in a galaxy. There’s not many.

If you have a normal star, the fraction of having these sort of binaries requires a specific evolutionary pathway that leads to this close compactness at the most extreme and you can have two white dwarfs orbiting each other every five minutes, but those are extremely rare. The process of mass transfer is a very sedate one, it moves material into a disc, sometimes the disc goes into an outburst and the system brightens up. You can see that. For these cataclysmic variables, as we call them, that happens maybe once every month, in the process, and lasts a couple of days and then it goes back into a quiescent state. The nova outburst that, happens on the white dwarf that can happen on time scales of once every thousand years or, or once every few hundred years.

There are a few known in the galaxy that recur on a timescale of 20 years or 30 years, but typically that’s a much longer process. 

Dan: [00:13:38] You’ve just published a paper on one such detection using MeerKAT. How exactly when these things are rare, how is, how is MeerKAT picking these up? Are you looking all the time for them or what is the strategy for finding these?

Patrick: [00:13:51] That’s an interesting question. So with MeerKAT, we’ve been using the telescope now since July 2018 a little over a year and a half and what we do in this particular program to study the X-ray binaries, so the accreting neutronl stars and black holes is to monitor a number of systems that are active and we know that they are active from the X-ray emission, what we discussed earlier.

So when you see X-ray emission, you know that there’s active accretion going on. So we follow active systems through X-ray monitoring. There are a number of X-ray satellites that pick these objects up and once we see them, we include them into our weekly monitoring list on MeerKAT once a week. We have a monitoring slot where we typically sample maybe four or five of these systems, for 10 or 15 minutes. It can be quite a short exposure because MeerKAT is so sensitive. 

Jacinta: [00:14:43] Oh, wow. I didn’t realize it was so short. So this is the ThunderKAT project?

Patrick: [00:14:47] That’s right 

Jacinta: [00:14:48] From past research and observations. You already know where these binary systems are, is that right?

Patrick: [00:14:53] Mostly, but some are new.

Jacinta: [00:14:54] Some are new, okay and then you can see them because they’re in the X-ray, which is picked up by a different telescope, is it SWIFT?

Patrick: [00:15:01] SWIFT is one of the telescopes that’s very good for monitoring. This particular one that we just published in Nature Astronomy is called MAXI J 1820+07 that just tells you where it is in the sky.

But the MAXI telescope is an X-Ray telescope that’s housed on the international space station. 

Jacinta: [00:15:17] Cool! So this is obviously up in space. We need it to be above our atmosphere, which absorbs all of the X rays. All right, so these are, the telescopes are spotting these flashes of X-ray. So we know that something special is going on in these binary systems, probably some accretion and then, would this weekly monitoring program you have with MeerKAT, you go on and look at these systems with our radio telescope. 

Patrick: [00:15:40] That’s right. 

Jacinta: [00:15:40] Yeah and then what do you see? 

Patrick: [00:15:42] We make images of these things. So we look at this variability or this time-domain astronomy, if you wish, with MeerKAT making images of the data and so we can spatially resolve phenomena that are related to such and such an event. So some of these systems, X-ray binaries are known when they are in this heightened state of mass transfer to eject a transient jet that comes from the system the jet moves at very high velocities, almost the speed of light and sometimes they appear to go faster than the speed up light, but it’s just a projection effect. What we do in this monitoring campaign is to study the behaviour of the X-ray binary during this bright state to understand how accretion is linked to outflow, how the accretion probed by the X-rays is linked to outflows as probed by the radio emission and in this particular case we saw the transient jet resolved in the image and move away at very fast, proper motions on the sky. So we could see the two jets on either side of the binary move very fast. 

Dan: [00:16:45] A couple of things that a transient, a transient jet is something which just happens once. It happens for a short period of time?

Patrick: [00:16:53] So in these systems, when the X-ray binaries and acquires a mode of accreting it is thought to have a permanent jet that ejects particles and when the accretion switches on that permanent jet gets disrupted. So the accretion disk then dominates and a transient jet is sort of ejected at that point. So transient with transients we mean something that varies with time. 

Jacinta: [00:17:15] Okay, so something that’s not always on, right? ThunderKAT has already put out its first publication, is that right? It came out in Nature Astronomy Journal on the 2nd of March this year, 2020 and Nature Astronomy is quite a prestigious journal. Meaning it’s a very important discovery. So tell us from the start, what this discovery was. 

Patrick: [00:17:36] This particular observation made it into Nature Astronomy because it told us something new and something special about the bay X-ray binaries for a number of reasons. So we were looking at a X-ray binary that suddenly went into a high state of mass transfer.

We took images with MeerKAT over a long time about three months after the outburst, till half a year after the outburst and from that time series of images that we took, we could see two blobs, blobs, for lack of a better word, blobs on the sky, moving at very fast, apparent motion on this sky that was associated with this ejection of material.

Jacinta: [00:18:15] And do you know what the compact object was?

Patrick: [00:18:17] In this case, the compact object is a black hole, stellar-mass black hole. 

Jacinta: [00:18:20] So it’s a black hole going around a normal star. 

Dan: [00:18:23] The other way around. 

Jacinta: [00:18:25] The black hole one has more mass than the other, right 

Patrick: [00:18:28] Going around the common centre of mass. 

Jacinta: [00:18:31] That’s our undergrad physics coming back to us. Okay so you saw these two blobs on the sky with radio and you mentioned that one of them seems to be superluminal, which is this beautiful word that means travelling faster than the speed of light. So what’s going on there? 

Patrick: [00:18:48] The jet itself is moving close to the speed of light. And the approaching jet, because it’s closely aligned to our line of sight, it appears to be moving faster than the speed of light, but this is an apparent effect. It’s just a geometric effect that you can easily calculate. You could work out what the actual velocity is based on that. The real key aspect of this particular observation is that we observed it with MeerKAT which has 64 antennae based over an eight-kilometre baseline, giving you a specific resolution.

At the same time, we’ve also observed with the eMerlin radio telescope in the UK, which is an array of telescopes over the full length of the UK, giving us a much higher resolution image and so we were able to resolve the relativistic ejector on two different scales and by doing that, we can calculate the energy of the injection of energy into these jets.

And that wasn’t done before and we realized that the energy that was launched into these jets was much larger than we previously thought. So that was the new insight into the behaviour of X-Ray binaries and black hole ejections.

Dan: Relativistic ejector?

Patrick: Moving at the speed of light or close to the speed of light.

Dan: [00:20:04] You just throw that one in there hey? So, so basically this is the, so you’ve managed to measure the energy which this gas was thrown out of the system. 

Patrick: [00:20:14] That’s right. By observing it with two different telescopes at the same time, but different resolutions and that allowed us that, that extra insight. 

Dan: Very cool.

Patrick: So you mentioned earlier this was the first paper, but in fact, we have eight papers out already on ThunderKAT. 

Jacinta: [00:20:28] Oh really? 

Patrick: [00:20:31] Yeah.

Jacinta: Oh my goodness. I didn’t realize there are so many

Patrick: Exactly so there is a whole range of papers. We’ve discovered our first radio transient and it’s turned out to be a very unusual binary star and that paper was published also earlier this year by Laura Dressen, who’s a PhD student in Manchester.

Jacinta: [00:20:43] What was it? This weird system that you found.

Patrick: [00:20:46] In this case, it was a stellar binary of a star that is very active chromospherically, very active. So the Sun sometimes has chromospheric activity. This particular star is very active. It’s called an RS CVN binary named after its prototype. It has a 22-day periodicity and SALT was able to take spectra to confirm its nature and so with the radio, we could see it move up and down in brightness. Sometimes it wasn’t there at all. Sometimes it was, they’re very bright and so on this weekly monitoring schedule that we do, we are, we are hoping to find many, many more of these radio transients.

And this was the first one of its kind. 

Dan: [00:21:27] You’ve detected all these things with ThunderKAT. For the one we were just talking about, the compact object. You followed up with another radio telescope and for this one, you were following up with SALT, is there a formal program for following up these things in different wavelengths for when you find a transient object, do you have the capacity to follow up with other telescopes immediately?

Patrick: [00:21:50] This is a very good question. The nature of this, this kind of astronomy is very much multi-wavelength astronomy. We mentioned earlier that the X-rays trace parts of the physics of these binaries, the radio traces another part of the physics. 

In the optical with spectroscopy, we can characterize the binary using optical spectroscopy to see what the nature of the stellar component is or stellar companion is and so ideally you want to have a network of telescopes around the world that can follow these things simultaneously or quasi-simultaneously. Now, when we designed the survey to find all these new objects in the radio data trying to make MeerKAT and later the SKA has a transient discovery machine.

This particular question came up, how do we characterize these systems at other wavelengths? And so that’s when Paul Groot, who’s a colleague of mine, and Rob Fender and myself, sat together and said, well, let’s build our own telescope, the MeerLICHT telescope that will follow in real-time wherever MeerKAT is looking at the same part of the sky.

So we have an optical telescope that will always co-observe with MeerKAT. So if we find something, we will know in optical, what that part of the sky is doing and we can then relay that automatically almost directly to telescopes like SALT. There is a program on SALT that allows for immediate or very fast follow up of any, any unusual kind of behaviour.

Dan: [00:23:15] So that is basically that MeerLICHT, this optical telescope, tracks wherever MeerKAT is looking and the moment that something is identified as with MeerKAT, you see if it’s also visible in the optical. 

Patrick: [00:23:32] That’s right. 

Dan:  and then if necessary, you can follow up with a larger telescope such as SALT

Patrick: That’s right. 

Dan: [00:23:33] So then on what sort of timescale are you analyzing this data? Is the ThunderKAT data analyzed instantly? 

Patrick: [00:23:39] Almost instantly. The aim is to do it in real-time. What we’re doing at the moment is that once the data gets taken from the Karoo, from where the telescope is, it gets moved to the archive, the South African Radio Astronomy Observatory archive and we pull it into our cloud-based compute resource at the university.

There’s the Inter-University Institute for Data-Intensive Astronomy (IDIA) and that is a cloud-based computing facility where we analyze all our data and within an hour of the data being taken, we move it across. That process goes quite quickly depending on how, how large the data set is and then we can immediately reduce and analyze our observations.

So within 24 hours we will know what’s going on. 

Jacinta: [00:24:23] So you need a supercomputer cluster to be able to process all of this data? 

Patrick: [00:24:28] That’s right. 

Dan: [00:24:29] And is this automated or does somebody have to be sitting there? 

Patrick: [00:24:31] It is fairly automated. There are a number of scripts that we can run and that that sort of then takes it in in a semi-automated way.

The goal is to develop this into a fully automated pipeline where we work in near to real-time. To see what’s happening so we can respond in near-to-real time. The optical data gets also transferred from Sutherland in this case, to the same compute infrastructure at the university and there an image gets ingested once it’s completed.

 So every minute at the moment, we’ve got a minute cadence on the optical telescope, a minute repeat timeframe. So at the moment, every new image gets ingested into the database, automatically reduced and that’s then injected into a database of sources all over the sky. 

Dan: [00:25:18] So does the feedback work the other way around too? If MeerLicht observes something that’s transient does it tell MeerKAT?

Patrick: [00:25:25] Eventually, yes, at the moment we are still testing out our transient detection algorithm on the MeerLICHT in the optical sky. Uh, you have to be careful for what’s called false positives and they can be artefacts in the data analysis that might look like a transient, but in fact, it’s, it’s an artefact of the data reduction.

And you have to be very careful not to issue false alerts. But eventually once that is working and once we’re finding transients in the optical database, we would like it and in some cases to feed that back to MeerKAT, but that needs to go through a program, maybe a ThunderKAT program where we have a target of opportunity where we can point the MeerKAT telescope and, but if a transient is occurring in the field, in the MeerLICHT of data, we most likely will have MeerKAT data on that field because the two telescopes are tied together in that sense.

So we should be able to see what’s going on in the radio at the time where we see an optical. 

Jacinta: [00:26:22] And that’s really impressive that you’ve essentially attached this optical telescope to the radio and it tracks exactly the same position as whatever the radio telescope’s looking at at that moment. Has this been done before?

Patrick: [00:26:34] Not, not as far as I know. So the unusual thing here is that the MeerKAT telescope has a very large field of view, which is great for finding new transients. It increases your probability of finding something in the field of view because you just looking at a much larger field of view. But traditionally optical telescopes have a much smaller field of view.

So to match that MeerKAT field of view, which is typically one square degree of the sky. So imagine a grid of two by two full moons together to match that in the optical. We needed to design a wide-field camera that is both a simplistic and operation for robotic operation as well as giving you that wide field of view.

And so the design then led to the MeerLICHT concept, which has a single electronic camera underneath. With 110 million pixels, which can be read out in seven seconds. So, it’s a lot of pixels can be read out in seven seconds. So we take an image of the sky every minute and then seven seconds later we can take our next image.

The data flow from that is, it’s not too high. Although you mentioned earlier, the ThunderKAT data flows is quite large, at the moment it’s about a hundred gigabytes for every one hour of observation and that’s in the low time resolution, a low-frequency resolution that can easily be up to a factor of 30 more.

Jacinta: [00:28:02] I imagine that because you have, it has to have such a wide field of view to match MeerKAT. You’d have to have some sort of trade-off? Probably sensitivity? 

Patrick: [00:28:11] Yeah, so, so we can do the optical design of the telescope that that simultaneously has that wide field of view. You optimize very quickly to a telescope size of about 0.6/0.7 meters.

So that’s smallish for an optical telescope. But within a minute of observation, we’d reached down to a magnitude of 21. 21st magnitude, for point sources for star-like sources, which is at this stage, the optimal limit for a spectroscopic follow up on SALT. The bigger the telescope, the more sensitive.

But with our current design within the minute we, we basically have an optimal follow-up for SALT and we can reach a very faint level of brightness. 

Jacinta: [00:28:52] Okay. It’s got a pretty good sensitivity, or I guess brightness limit, which is the equivalent word in optical astronomy. Not radio. So this is going to say there was something seen with MeerKAT we saw at the same time in the optical. This is an interesting thing. Now let’s go and look at it again with SALT, which is a more sensitive, bigger telescope, right? 

Dan: [00:29:13]  So you seem to be pretty well set up to detect these transients and we, I mean, we were just chatting earlier about one you’ve detected and you have detected a few now with MeerKAT, we really are expecting some new discoveries. There are things we can’t expect to find. In your mind and in the field of transients, what are you expecting? What is exciting with MeerKAT? 

Patrick: [00:29:37] The exciting thing in time domain astronomy is to look at things that vary on very short timescales. I think over the last 10,20,30 years, we very well characterize things that vary on a timescale of days or weeks or months. The Nova explosion, the Thermonuclear explosion on the white dwarf that I mentioned earlier, those are fairly well studied, but we know very little about how the objects in the night sky vary on timescales, less than a day on time scales of an hour or a minute or even below a second.

There’s very exciting objects called fast radio bursts and that gives you a single pulse of maybe 10 milliseconds in, in time that comes from cosmological distances in galaxies, far, far away and we want to characterize those sources. We are now discovering, astronomers are now discovering these in quite large numbers, but still with fairly poor localization in the sky, although that’s getting better.

So one of the things that MeerKAT and MeerLicht can do is to identify and locate them, but also locate the optical counterpart to those fast radio bursts, the host galaxy in which these things reside. These are once-off events if you’re not on the sky when, when this happens, you would have missed it. So by having the wide field of view, you have a greater probability of finding these things 

Dan: [00:30:57] and nobody has observed that yet?

Patrick: [00:30:59] Some have been observed some of these systems are repeating sources and we don’t quite know why. Some are repeating and some are not repeating. But for some of the repeating fast radio bursts, they have been localized quite well and there are host galaxies associated with them. 

Jacinta: [00:31:14] Well, we have so many questions about transients because we know so little about it and we can talk about it all day, but I know you’re a busy person.

We have to let you go soon. Before that, I’d like to just talk about the University of Cape Town Department of Astronomy because it’s celebrating a special anniversary this year. 

Patrick: [00:31:28] That’s right. Thanks, Jacinta for asking that. This year, it’s our 50th anniversary of the astronomy department at the University of Cape Town. It was established in 1970 as a formal department,  versus astronomy departments around the world which actually are part of a physics department. Ours grew out of the physics department at UCT the director of the observatory in Cape Town was an honorary professor of astronomy in the department of physics. But at the time when the observatory changed into the South African Astronomical Observatory and the Sutherland Observatory was being established in the Northern Cape in South Africa and the University of Cape Town decided that it was time to set up its own department of astronomy, which is now 50 years ago. So we’ve, we’ve been doing great astronomy in the last 50 years and there’s a lot of excitement, of course with SALT and MeerKAT to look forward to and we’re celebrating this wonderful milestone with a lot of activities, public talks, outreach events and so on.

Jacinta: [00:32:30] And I’m a part of the current generation there as a postdoc at UCT, are there any of the celebration events that some of our listeners, particularly those in Cape Town can participate in? 

Patrick: [00:32:40] We’ve had a number of things already. We had a public talk by the president of the International Astronomical Union recently.

But throughout the year, we’ll host a number of talks and events. We will advertise them on our website and on our Facebook site as well. We will post them to the public and given the close history that our department has with the South African Astronomical Observatory who is also celebrating a major milestone this year. We will see how to coordinate the 200 anniversary of the SAAO with activities around the 50th anniversary of the Astronomy Department. 

Jacinta: [00:33:11] Oh, great. Well, Dan’s sitting right next to you and he’s running those

Dan: [00:33:15] Patrick and I have spoken already

Jacinta: [00:33:17] Okay.  

Dan: [00:33:19] we’ve, we’ve come up with some ideas which we will implement.

Jacinta: [00:33:22] And Patrick, are there any significant moments that happened in the last 50 years of the UCT Astronomy Department?

Patrick: [00:33:30] Sure. That’s a, that’s a big question. 

Dan: [00:33:33] Well, at least what you can remember. 

Jacinta: [00:33:36] Well, you gave a really great talk at the start of the year about the history of the department and there were quite a few 

Patrick: [00:33:42] there. Lots of wonderful milestones. So we, we’ve had great people, great students coming through the department, people who’ve gone on to find significant posts across the country, across the globe in astronomy.

In terms of the work that we’ve been doing over the last 50 years. It’s quite interesting to see that the astronomy department started with, in 1970 was searching for supernovae and galaxies and studying compact binaries and the astrophysics of these cataclysmic variables that a lot of new insight has been gained in those, in those areas and that the astronomy department is still doing a lot of work in these areas, particularly, I think the highlight has been the inclusion of radio astronomy over the last 15 years with, with MeerKAT on the horizon. We’ve become specialized in radio astronomy, both in the stellar astrophysics side, but also in extra-galactic astronomy. The study of neutral hydrogen, for instance, is one of the strengths in the department I’m very proud of. 

Jacinta: [00:34:41] Awesome and just lastly, before we let you go, are there any other final messages you have for listeners. 

Patrick: [00:34:47] So, so one of the things that’s happened in the astronomy department over the last 15 years, since 2006, is that we restarted our major in astrophysics and that’s grown and grown.

And this year we have 25 3rd year students which is the largest group that we’ve ever had and we organize open days and so my message, to people who are out there who consider a career in astronomy is be curious, be inspired by what goes on in the sky. There’s a lot of things still to discover.

MeerKAT is a fantastic machine, so for the next generation of astronomers in South Africa and the learners at schools, if you want to know what the Universe is made out of you’re in the right place to come and study that. 

Dan: [00:35:30] Great. Thank you very much for joining us, Patrick. We really appreciate your time.

Jacinta: [00:35:34] Thanks, Patrick. 

Patrick: [00:35:35] Great pleasure. 

Jacinta: [00:35:35] Talk to you again soon. 

Dan: [00:35:37] Thank you. When you make another discovery

Jacinta: [00:35:49] All right. I think this concept of MeerLicht is very, very cool to have an optical telescope that’s essentially attached to the radio telescope so that it’s looking at the same place as the radio telescope at all times. 

Dan: [00:36:02] Yeah, I, I mean, we’ve talked about ThunderKAT, that awesome discovery, there’s going to be a lot more from MeerKAT, but getting more and more wavelengths involved yeah and I think it’s just going to be another fascinating avenue of astronomy to go down. So the MeerLicht telescope is, is definitely gonna make some awesome discoveries and contribute to, to some of the discoveries we’ve already made. You know, a very, very exciting project. Very cool and as you said, the first time that this has been done somewhere in the world.

Jacinta: [00:36:31] Yeah, because usually, one telescope in one particular wavelength will spot an interesting object and then send out an alert to all other telescopes, which will then look at it. But in the time it takes for that alert to be made, the transient occurrence may already be finished. So it’s really great that you can have at exactly the same time, both radio and optical observations.

Dan: Yeah, you should note that sometimes those alerts go out in seconds

Jacinta: Sure. Yeah. 

Dan: [00:36:58] and telescopes, can follow up, but the seconds are sometimes not enough for these transients. 

Jacinta: [00:37:03] Yeah, exactly. All right. I guess so the 50th-anniversary celebrations of UCT and the 200th-anniversary celebrations of the observatory, is that going to be, I guess that’s going to be impacted a bit by this Coronavirus lockdown?

Dan: [00:37:19] Yeah, for sure. So we’re not really sure how this is going to go and where we’ll be in October most of the celebration were planned, but at the moment we are talking about various contingency plans, potential postponements, we planned a large astronomy festival. First of all, we are looking at maybe doing it virtually, which will be quite cool actually.

It’s definitely concerning, but the least of our worries right now, I think everyone’s health is is a bigger concern and trying to keep safe. 

Jacinta: [00:37:48] Yeah, exactly. Everyone’s health and safety is by far top priority. 

Dan: [00:37:53] Yes. Keep safe out there guys

Jacinta: [00:37:55] Yeah. Wash your hands, keep social distancing. You know the deal. All right. Good luck everybody and we’ll hope to chat to you again soon.

Dan: All right. See you later. 

Jacinta: Okay. Dan’s logged off Skype, so that leaves me to do the credits. Thank you very much for listening and I hope you’ll join us again for the next episode of the cosmic Savannah. You can visit our website, thecosmicsavannah.com where we’ll have links related to today’s episode.

You can follow us on Twitter, Facebook and Instagram @cosmicsavannah. That’s Savannah spelled S. A. V. A. N. N. A. H. Special thanks today to Professor Patrick Woudt for speaking with us. Thanks to Mark Allnut for music production, Janus Brink for the Astrophotography. Lana Ceraj for graphic design and Thabisa Fikelepi for social media support.

Also to Sumari Hattingh, Brandon Engelbrecht and Lynette Delhaize for transcription assistance. We gratefully acknowledge support from the South African National Research Foundation, the South African Astronomical Observatory and the University of Cape Town Astronomy Department to help keep the podcast running. You can subscribe on Apple Podcasts, Spotify, or wherever you get your podcasts and if you’d like to help us out, please rate and review us and recommend us to a friend. Stay safe everyone and we’ll speak to you next time on The Cosmic Savannah.


Episode 22: Milky Way blowing bubbles!

with Dr Fernando Camilo

This week we are joined by Dr Fernando Camilo who is the South African Radio Astronomy Observatory (SARAO) Chief Scientist, where he directs the scientific program of MeerKAT to ensure the maximum scientific productivity of the telescope.

We chat with Fernando about MeerKAT and the incredible science it is doing. In particular, we discuss the recent discovery of enormous balloon-like structures that tower hundreds of light-years above and below the centre of our galaxy.

Caused by a phenomenally energetic burst that erupted near the Milky Way’s supermassive black hole a few million years ago, the MeerKAT radio bubbles are shedding light on long-standing galactic mysteries.

This week’s guest

Featured Image:
A radio image of the centre of the Milky Way with a portion of the MeerKAT telescope array in the foreground. The plane of the galaxy is marked by a series of bright features, exploded stars and regions where new stars are being born, and runs diagonally across the image from lower right to top centre. The black hole at the centre of the Milky Way is hidden in the brightest of these extended regions. The radio bubbles extend from between the two nearest antennas to the upper right corner. Many magnetised filaments can be seen running parallel to the bubbles. In this composite view, the sky to the left of the second nearest antenna is the night sky visible to the unaided eye, and the radio image to the right has been enlarged to highlight its fine features.

Related Links:
MeerKAT: https://www.sarao.ac.za/science-engineering/meerkat/
Inflation of 430-parsec bipolar radio bubbles in the Galactic Centre by an energetic event, by I. Heywood et al., is published in the 12 September 2019 issue of Nature. The article is available at https://nature.com/articles/s41586-019-1532-5

Episode Transcript

(By Sumari Hattingh)

Dan: [00:00:00] Welcome to The Cosmic Savannah with Dr. Daniel Cunnama

Jacinta: [00:00:08] And Dr. Jacinta Delhaize. Each episode, we’ll be giving you a behind the scenes look at world-class astronomy and astrophysics happening under African skies.

Dan: [00:00:17] Let us introduce you to the people involved, the technology we use, the exciting work we do, and the fascinating discoveries we make.

Jacinta: [00:00:24] Sit back and relax as we take you on a Safari through the skies.

Dan: [00:00:35] Welcome to episode 22

Jacinta: [00:00:36] Hi, welcome back. Today we’ll be talking to the SARAO chief scientist, Dr. Fernando Camilo, about an exciting Nature paper publication that’s come out from the MeerKAT telescope where they found huge bubbles around the center of the Milky way.

Dan: [00:00:54] And SARAO is?

Jacinta: [00:00:56] The South African Radio Astronomical Observatory.

Dan: [00:00:59] Yes.

Jacinta: [00:01:00] I hesitated for a second. It used to be called SKA South Africa, and now it’s been renamed.

Dan: [00:01:08] So first we should probably let our listeners know that we know have transcriptions of our episodes available.

Jacinta: [00:01:13] Yes, that’s right. So we have a dedicated team of student volunteers who have very laboriously been going through and transcribing each episode.

I think almost all of them are done for season two and we’re yet to start attempting season one. So if you or anyone you know is perhaps hard of hearing or it would just help you to read along as you’re listening, head over to our website on the blog for each episode will be the full transcription of what we’re saying.

Thank you to our volunteers.

Yes, very much so. Yeah.

Dan: [00:01:44] We’ve received a lot of positive feedback about the podcast. Thank you to all our listeners.

Jacinta: [00:01:48] Thank you very much.

Dan: [00:01:49] And as always, if you, if you do have some feedback of any form, leave a review for us on, on iTunes or.

Jacinta: [00:01:56] Preferably on iTunes, but wherever you, whatever you have access to, I know you’ll hear this on every single podcast that you listen to, but it really, really, really helps us.

It helps us to reach new listeners if you can rate and review us. And of course, the one of the best way to spread the news is by word of mouth. So if you can tell your friends and family about us, if you think they’ll enjoy it, we’d be very grateful.

Dan: [00:02:17] Okay. So should we get into today’s episode?

Jacinta: [00:02:19] Yes. On to science,

Dan: [00:02:20] All right. Today we’re joined by Dr. Fernando Camilo, as you said, who is the chief scientist for the South African Radio Astronomy Observatory. And he’ll be talking to us about this exciting Nature paper.

Jacinta: [00:02:32] Yeah, that’s right. So he’s a big gun here in astronomy in South Africa, and we’re very excited to talk to him about this topic.

Several listeners have requested it. So in September, 2019 so at the end of last year. One of, I think it’s the first MeerKAT paper publication came out and it was published in the world’s most reputable journal – science journal – Nature, and only papers that are very, very important, which are presenting something very important or very new, some previously unknown phenomena are allowed to publish in Nature. This research was so significant that it was accepted. It was important because they found for the very first time, huge radio plumes or bubbles emanating from the center of the Milky Way. And this hasn’t been seen before in any galaxy.

So this is something brand new.

Dan: [00:03:24] So we should point out that by a radio bubble, we mean a big bubble of gas, which is visible at radio wavelengths.

Jacinta: [00:03:32] Yeah, that’s right. And bubbles had been seen before from the center in gamma rays. Very, very huge bubbles called fermi bubbles. And this is the first time it’s been seen in the radio.

So it’s a pretty big deal. And we don’t yet know what’s causing it. It could have something to do with the supermassive black hole at the center of the Milky Way called Sagittarius A star. Maybe that’s ripping apart stuff, some stars and gas and dust and creating these bubbles, or it could be a sudden burst of supernovae.

We’re not really sure yet, but Fernando tells us the backstory behind this discovery and what led to it.

Dan: [00:04:07] Yeah, it’s great to see MeerKAT already producing world-class science, getting into Nature, and I think that we’ve got some exciting years ahead.

Jacinta: [00:04:15] That’s right. So MeerKAT, as we have discussed in previous episodes, is one of the most powerful radio telescopes in the world.

It’s right here in South Africa in the Karoo. It’s fairly new. It consists of 64 antennas, which looks kind of like satellite dishes and they’re picking up radio waves from space, and one day it’ll be incorporated into an even larger telescope called the SKA, the Square Kilometer Array Radio telescope. And this is just as, as you’ve said, just now, Dan, the beginning of a huge revolution in radio astronomy and science discoveries.

Dan: [00:04:48] We should probably also point out the recent news about MeerKAT, that there was a further investment from Germany to expand the 64 dish array with an additional 20 dishes.

Jacinta: [00:04:58] Gosh, very exciting.

Dan: [00:04:59] So that’ll also lead into the SKA. Ultimately. But this is funded and this will be happening over the next two years.

So we expect those dishes to be going online next year. 2021

Jacinta: [00:05:10] so soon. That’s exciting. Oh my goodness. I didn’t even know about that.

Dan: [00:05:14] It is

Jacinta: [00:05:15] hot off the press.

Dan: [00:05:16] Exactly. So there’s some, some really exciting stuff happening.

Jacinta: [00:05:18] Yeah. And there was actually also another Nature paper incorporating MeerKAT released at the time of recording.

It was released this week, on Monday. The…

Fernando: [00:05:28] Second

Jacinta: [00:05:29] Second, I think it was the 2nd of March, and that was about a low mass binary system, which if you’ve heard episode 21 you know all about that. When we talked to Tana Joseph, she explained what that was. It’s a black hole with the star going around it, and in this case it seems to be releasing this huge jet of radiation, which is traveling very, very fast, and it’s super luminal, which means it’s traveling faster than the speed of light. Yes. Well, it appears to be traveling faster than the speed of light, but of course we know that nothing in the universe actually can. Anyway, I’m revealing too much. We’ll, we’ll leave the rest for another episode that’s coming up very soon.

Dan: [00:06:05] Okay. I think we should hear from Fernando. It was wonderful to chat to him. Great interview.

Jacinta: [00:06:10] Yeah, let’s hear from him.

intro_music: [00:06:13] music intro

Dan: [00:06:18] Today. We are joined by Dr. Fernando Camilo, who is the chief scientist at the South African Radio Astronomy Observatory, SARAO. Welcome to The Cosmic Savannah.

Fernando: [00:06:27] Good morning. Thank you.

Dan: [00:06:28] Fernando, if you can just start by telling us a little bit about yourself and how you got to be here in South Africa. You’re not originally from South Africa and how you got to be working at SARAO.

Fernando: [00:06:37] Yeah, sure. That’s right. So I’m not from South Africa. You can tell from my accent. I was born in Portugal, and then when I was 18 I went to the US to study and I did most of my career there. I was a an astronomer studying pulsars, these very tiny neutron stars. And then in 2015 I received an email that had some results from the first MeerKAT dish.

MeerKAT is a big radio telescope up in the Karoo. And I had known – I’d first heard of MeerKAT back in 2009 when the SKA South Africa project had issued a call for proposals from the international community to use this feature. Very, very exciting. A sensitive new radio telescope that was going to be built in South Africa called MeerKAT.

So I was part of one of the teams that was awarded some telescope time back in 2009. But then our South African colleagues went about building this MeerKAT telescope, and in 2014 the very first dish, MeerKAT is made up of 64 dishes separated by up to eight kilometers up in the Karoo. I received a plot that showed the sensitivity of this one dish.

And I was really stunned because it was roughly twice as sensitive as we have been led to believe back in 2009. I went back to my notes to confirm that was the case, and this is very unusual because when you build these high tech projects, you’re very lucky if you reach the design goals, you don’t surpass them by a factor of two.

So I was very interested about that. I contacted my colleague, I said, there must be some factor of two wrong in this plot. Someone forgot to divide by two or something, and a few days later he confirmed to me that, no, this is real. This was the sensitivity of a MeerKAT dish. And at that point I got really interested.

Well what’s happening? Because South Africa didn’t have really a very large profile on the international radio astronomy community, let’s say. And so that led me to, in 2015 I came, there was this job opening SKA South Africa chief scientist, and I thought of doing a career change and moving to a different country and doing a different job.

And yeah, I ended up coming here because of MeerKAT. Now back in 2016 when I arrived, MeerKAT was still being built. The very first image hadn’t even been been made. But since then, in the past two or three years, a lot has happened.

Jacinta: [00:08:47] So this telescope was designed and then it ended up twice as good as it was planned to be.

Fernando: [00:08:52] Yes. Something like that. It’s remarkable.

Dan: [00:08:55] So how, how was that achieved exactly, right? Maybe not. Exactly. Yes.

Fernando: [00:09:00] That was the question I had from my colleagues here in South Africa when I arrived for my job interview back in September of 2015 and I spent three or four days in Cape Town, you know, apart from the job aspects of it. I was trying to figure out if I’d like to move to this beautiful city, which I’m very glad I did, but I said, I remember sitting down with one of the brilliant engineers in the office and asking him just that, ah, how did you do this? And the funny thing was basically, long story short, it was all about design, engineering, optimization of a design.

So it’s an interesting thing also, sociologically from the perspective of science, sociology, if you will, in South Africa. South Africa, as I said, didn’t have much of a history of radio astronomy, so it didn’t have too many radio astronomers. Now when you go and build a new radio telescope in Australia, or in the United States or in the Netherlands, all countries that have a very long history of radio astronomy, of course there’s engineers involved, but also the astronomers are very much involved in building the radio telescope.

You know, some of the old timers, probably built the first Radio telescopes with their hands and so on. And so there are a lot of inputs into the design of a new radio telescope. But in South Africa because it didn’t have that history, what you did, however, have was a very proud and very long history of brilliant engineering.

Something to do with the history of the country, the details of it. But in any case, there’s brilliant engineers in fields like radar technology. Which are very much relevant for, for building a radio telescope. So long story short, the way that my colleagues went around building MeerKAT was really substantially different from what a normal, the way normal telescopes get built around the world.

So it had a lot more engineering input, a lot more design, reviews. I like to joke that with MeerKAT, you don’t build the screw unless there’s 300 pages of documentation and one of the results of that is, well there, there are many consequences of that. So one is that by optimizing every single bit of the design and then re-optimizing, as that colleague of mine explained to me in 2015.

Our colleagues just squeezed out that last little bit of performance that you could from sort of a standard design, and then these telescopes are incredibly complex machines. I mean, they’re really data machines that generate enormous amounts of data. There are many subsystems that all have to work together, and it’s very complicated.

So many of these telescopes when they get built and they get inaugurated, like MeerKAT was inaugurated in 2018 often, it still takes, takes a year thereafter to, to generate science, to generate very nice images because it takes so long to commission; to understand it backwards and forwards. But MeerKAT pretty much just work right out of the box because of that care and thought that went into the design and the design reviews and prototyping and so on.

So pretty much worked right out of the box and led to some very, very nice images that we are seeing today.

Dan: [00:11:51] And not just images. I mean science, right?

Fernando: [00:11:53] Of course. Ultimately it’s about science. I mean, it’s funny, we, we, these days there’s this discussion about big data and big, the words, big data everywhere.

And I was just thinking about this actually the other day. So you think of Google that we all use, right? And of course they’re involved in big data, but their business is really about making money. That’s what Google is about. It’s a public company. It’s either shareholders. Well, when you, when you look at a telescope like MeerKAT, our business is not data.

Our business is science. So we collect lots of data. We’re all swimming in data these days. We have many telescopes of all sorts. But the key thing is how are you going to convert all that data into science, into, into answering new questions, into writing journal articles that explain, you know, what you’ve learned and so on.

And that in turn requires large numbers of very clever young astronomers, scientists, and so on, which now exists in South Africa. Because along the way with building this really world-class radio telescope here in South Africa. Some of our colleagues invested in the human capital development aspect of it, and so now there are far, far, far more young radio astronomers than they were a decade ago or so.

Jacinta: [00:13:04] So speaking of the amazing science that MeerKAT can produce, one of the very first papers that it produced was actually published in one of the world’s most prestigious science journals, Nature. And that was led by Ian Heywood, in Oxford, and yourself here and at SARAO. Tell us what the paper was about.

Fernando: [00:13:23] Yeah. So that was very, very interesting. So the result is very interesting. It turns out so that we on Earth going around the Sun once a year, we are in turn going around the center of our galaxy, the Milky Way galaxy, which is a large spiral galaxy. And we go around the center of our galaxy every couple of hundred million years or so, and we are roughly 25,000 light years away from the center of the galaxy.

So it takes light, including radio waves, 25,000 years to travel all the way from the center to us. The center of our galaxy is a very, very interesting place. It’s unique. Of course, there’s only one center about which we rotate, but it has a very massive black hole, so there’s a black hole at the center that weighs roughly 4 million times as much as our Sun.

So all sorts of things happen near the center of our galaxy that don’t really happen anywhere else. So astronomers are always very interested in looking at what’s happening at the center of the galaxy. This paper reports the discovery of these massive bubbles, the this sort of this bipolar outflow North and South of the center of the galaxy to these plumes of radio waves.

Over a thousand light years in length that we discovered with MeerKAT and nobody knew they were there, so we discovered that. Then in the paper we explained what we think that might be due to some sort of explosion – explosive events that might’ve happened at the center of the galaxy 7 million years ago or so.

So that’s, I mean, the science of it. And then people will do more detailed work and follow-up work, investigating what does this mean for other things we know at the center of the galaxy. So it’s all about basically understanding our environment in which we live on the galactic scale. And this was an important additional discovery.

Now there’s this very interesting backstory behind how we got to writing this paper, how we got to have these data that we analyze and finding these bubbles. So if you go back to early 2018 about six or seven months before the telescope was inaugurated, our colleagues are engineers at SARAO. We’re still developing many key capabilities of the telescope that were required to make it work as a functioning telescope.

So it’s made up of 64 dishes, large dishes, each of them roughly five stories high, up in the Karoo, as I said earlier, separated by up to eight kilometers. Now the dishes were all there. The dishes had been standing there for many months, since 2017 but a lot of the electronics behind it, etcetera, were still being developed.

And finally, it was on April 19th of 2018 when for the very first time, we had 64 MeerKAT dishes, all pointing in the same direction, collecting data from the same star or galaxy that we pointed the telescope to. So that was April 19th. Now. We knew that on July 13th that was going to be the inauguration of the telescope and that date wasn’t going to change.

And so we of course had to come up with some nice images to, to present to the public, to the distinguished guests that were there for the inauguration. And we were thinking about what to do. Now the sky is vast, you can point the telescope anywhere and find interesting things. And one day in May, – I remember it was early May – one night we had telescope time. That is, it was free that it wasn’t being used for tests. I think it was Ian, the first author of this paper myself thought, well, why don’t we point a telescope at the center of the galaxy. Eventually everyone who has a new telescope wants to pointed at the center of the galaxy, if they can.

But that usually takes years because the center of the galaxy is a messy place. You know, it has all these bright features and dim features and large extended scale structures and small features and all of that makes it just technically very complicated to come up with a decent image with radio waves, but we thought, Oh, what the heck?

We have these eight hours or so tonight, let’s do it. And then to our surprise, it came out really well. It looked good. And so then basically we spent the next month doing further observations to assemble this picture that we released at the inauguration on July 13th of 2018 – a very, very beautiful picture.

The clearest view of the center of the Milky way that has been done to date, with any telescope around the world. Now that was essentially for public relations purpose, right? That image was made for the inauguration of the telescope. Now we knew when we had it that the underlying data was also going to be useful for science, some science, but that required someone spending months and possibly years actually analyzing those data carefully.

Well, when we started looking at those data after the inauguration, I think in August of 2018, we soon found these funny features North and South of the center of the galaxy. We thought, whoa, that looks like a bubble up there. And the bubble down there and they seemed to be continuous. And then that was really the story.

And so that was August of 2018 and it’s took us, well, the better part of a year because he had to analyze the data fully and then to write the paper. And the paper, by the way, there are a handful of authors that did detail work on the specific dataset for the paper, but the authorship of a paper consists of roughly 100 people.

And the reason for that is that 95 or so of those people are people that had a critical role in building MeerKAT. There are what we usually call them, the MeerKAT builders list. Without those people, including policymakers, including managers, engineers, scientists, industry partners, university partners, MeerKAT just wouldn’t exist though.

They’re mostly South African, not entirely. So yeah, it’s an interesting story. Came about accidentally, but we’re very glad that we have it.

Jacinta: [00:18:53] How did you feel when you first saw those bubbles?

Fernando: [00:18:56] We were really, really happy. I mean, just visually we thought, okay, this is unusual. This is striking. This must mean something interesting.

Now those of us who looked, Ian and myself were, we’re not experts in the center of the galaxy these days. Radio astronomy, like many sciences, is very specialized. I’m an expert on pulsars and I know very little about the center of the galaxy. So even though Ian and myself spent the next year, well, learning a lot and reading lots of papers about the center of the galaxy so we could write a paper.

So we brought on board a colleague of ours from the United States, Furhad Yusef-Zadeh at Northwestern University, who’s an expert in some aspects of the physics of the center of the galaxy. So that also shows nicely the collaborative aspect of science these days. You know, it’s very international. And even MeerKAT, of course, we want young South African scientists to use it, it’s best done if we do this collaboratively with all the experts around the world.

But it was one of those things that sometimes happens in science. You look at it, you know, you have something, the minute it pops up on the screen, to your face. But then it can be quite a lot of work to actually disentangle the details and figure out what it really means.

Dan: [00:20:08] This discovery. Why MeerKAT? Why has this never been seen before?

Fernando: [00:20:13] That’s a very good question. Until MeerKAT, the, let’s say, well, the gold standard, and still in many ways, the gold standard of radio telescopes of this sort what we call the interferometer is made up of these many dishes put together, is the so-called Very Large Array in New Mexico in the US.

Although we can see the center of the galaxy much better from the Southern Hemisphere, which I’ll come back to in a minute, from the United States you can also look down towards the center of the galaxy for a few hours a day or each night. And so the very larger, I had made some images of this region in the best, and it had found some very interesting features, which we now see better with MeerKAT. But it didn’t quite have the technical capabilities to find these bubbles. Now, why these bubbles are actually relatively faint. They’re very extended large structures. And so the advantage we have with MeerKAT is two or three fold. So first of all, location. So it just so happens that the center of the galaxy, the center of the Milky Way goes right overhead.

Where MeerKAT is located is in the Northern Cape. So that means we can look at it from rise till set for approximately 12 hours a day or night because it’s radio waves and we can observe 24 hours a day. So we can look at it for 12 hours a day. Whereas say in the US you can only look at it towards the South, hugging the horizon for say, four hours.

So that’s one big advantage. Second advantage is that MeerKAT is now the most sensitive radio telescope in the world. At these frequencies that we operate at. So we collected radio waves with the frequency of roughly 1000 Mega Hertz. So roughly 10 times frequency of your FM dial at that frequency, MeerKAT is the most sensitive telescope in the world.

So that helps a lot. The one thing that helps tremendously is the number of what we call “baselines”. So it’s the number of dish pairs. If you think about it, if you consider a telescope with two dishes – made up of two dishes separated by, I don’t know, a hundred meters.

Well, there’s only one way in which you can combine those two dishes. Now, as you start adding more and more dishes, the number of possible pairs goes up as the square of the number of dishes. So with MeerKAT’s 64 dishes, you have 2016 possible combinations of dish pairs. And ultimately that allows you to make much sharper images of the sky, higher fidelity images of the sky.

These interferometers radio telescopes like the kind that MeerKAT is, don’t produce perfect images of the sky. There are always some artifacts, and the fact that we have 64 dishes in 2000 of these dish pair combinations, allows us to make essentially the highest fidelity images of the radio sky, than any telescope of this sort can make.

So all of those put together allowed us to make this discovery. There’s one additional thing, of course, which is normal telescopes, telescopes that are in production, allocate their telescope time on the basis of proposals that are submitted by scientists. Scientists want to investigate some phenomenon. They write a scientific proposal, say, I want 100 hours of telescope time to study this, that, and the other.

Now, we didn’t have to do that in this case because we had other constraints, other requirements; we needed to inaugurate the telescope. So we had the flexibility to, in particular, the moment we saw that we had something interesting that night in May of 2018, we had the flexibility to then spend the next month going back to this region of the sky to really study it very well.

So it was serendipitous. It was very exciting. And I’m very glad this was the first paper that was produced that was put out there based on the full MeerKAT – on the full 64 dish  MeerKAT.

Jacinta: [00:23:54] This is obviously a very exciting discovery and very important for the scientific community. Since it was published in a journal as prestigious as Nature.

Why was it so important and what caused these bubbles? I know these are two different questions, but the Milky Way is sort of more or less flat, like a dinner plate. We’ve got the center and then we on Earth, are sort of a little bit further out on the plate revolving around that center. And then these bubbles are coming above and below this plate, this plane of the Milky Way.

And they’re enormous. So what could possibly be producing so much energy that it could blow out these bubbles? And, and why is this important for us to know about?

Fernando: [00:24:33] Yeah, so, excellent question. As I mentioned earlier, at the center of the galaxy, there’s a massive black hole, 4 million times the mass of our Sun.

And what happens is that once in a while, gas and maybe stars that are nearby that black hole, they are swallowed up, or part of them are swallowed by the black hole. And maybe they’re torn to shreds in the process if a star, you know, falls into the black hole. And so there’s a lot of energy involved. And somehow through very complicated means that we don’t yet fully understand in galaxies in general, but some of is this energy is emitted.

This gravitational energy ultimately is emitted along generally in an axial direction. In this case, maybe North and South of the center of the galaxy. Now, we know of other features of the bubbles, etcetera, around the center of the galaxy, there are very famous so-called Fermi bubbles. They were discovered by the NASA’s Fermi Gamma Ray satellite back in 2010 or so, and these are enormous bubbles, much larger than the MeerKAT bubbles.

They spend roughly 50 degrees on the sky, North and South. Now, for comparison, the Moon on the sky subtends an angle of half a degree. So imagine on the sky bubbles that are a hundred times wider or taller say than the Moon, right at the center of the galaxy. These are the so called Fermi bubbles, and we don’t fundamentally understand what caused them.

And likewise, we don’t yet know what’s caused these MeerKAT bubbles that are smaller than the Fermi bubbles. They might be related. We’re not sure, but generally there are two sort of options. So one is, like I said, matter falls into the black hole periodically. It’s not always a constant flow of mass and stars being torn to shreds, perhaps in falling into the black hole.

They can be periods of higher or lower activity. So that’s one option. And the other option is that in a place like the center of the Milky Way, again, a very busy place. Once in a while, meaning over timescales of hundreds of millions of years, the star production rate increases tremendously. You can have periods where many, many more stars and massive stars are being formed.

And then some of these stars explode. And supernovae are the most massive explosions in the Universe. And those supernovae released a lot of energy, mechanical energy into the interstellar medium, which push out other outlying gas and so on. So these bubbles, the MeerKAT bubbles, could also have been produced by such a phenomenon and for technical reasons that we go into into paper.

We think something may have happened roughly 7 million years ago that caused these bubbles. So that’s one estimate of the age of these bubbles now. So that’s interesting for our own galaxy to understand a little better. You know, the environment that we find ourselves in, but of course our galaxy is just one amongst hundreds of billions in the Universe.

So many of us want to understand more generally how galaxies form, how they evolve. And in fact, that’s one of the key MeerKAT projects or goals with many types of observations to address this question of, you know, how does a galaxy like the Milky Way, which is say, roughly 10 billion years old, the universe is roughly 14 billion years old. Our galaxy is a little younger, but how did the galaxy come to be the way it is? How did we come to be here the way we are today? It wasn’t always dust like this but by looking at many galaxies throughout the Universe with MeerKAT telescopes, we do hope to understand better that process, that history, but of course, as with many things, the center of our galaxy is the closest center of a galaxy that we have.

So these MeerKAT bubbles, for instance, if they are present in many of the galaxies throughout the Universe, it’s really unlikely that we’ll be able to detect them. They’re so far away and so faint. So this allows us to have basically a closer example of a galaxy, namely our own, to study in great detail in ways that we cannot study other distant galaxies.

But of course, the idea is we’re not special. It’s just that we are closer to our own central black hole.

Jacinta: [00:28:23] So MeerKAT detected a phenomenon that’s no one’s ever seen before.

Fernando: [00:28:27]  That’s correct. That’s correct. And now MeerKAT, I mean, of course, this is the first example, but we have already been sharing data from MeerKAT with some of our colleagues in South Africa.

Many, many colleagues at universities, at the South African Astronomical Observatory, dozens of proposals, scientific proposals have been accepted and data has been shared. And our colleagues are analyzing those data. And soon I expect they will write their own papers, make new discoveries.

Dan: [00:28:55] This is an amazing discovery, obviously about the center of our galaxy, the gas around it.

We learn something about the supermassive black hole and how it interacts with that gas and, and our galaxy as a whole. What else are we gonna learn from MeerKAT?

Fernando: [00:29:11] Right. Very good question. So MeerKAT, as all instruments of this sort, they have to be optimized for something. MeerKAT is not the best in the world at everything.

Obviously, you know, when people ask me, so what’s the best telescope in the world? You can’t answer that question. Best for what? The Hubble Space Telescope that most everyone knows about circles up in Earth’s orbit, and it’s an amazing telescope. And it can do many things, but MeerKAT can do many things that Hubble cannot.

So these telescopes are optimized for doing something, and MeerKAT was particularly optimized to study hydrogen. Hydrogen is the most common, simplest element in the universe, and it’s the fuel that ultimately makes up stars and galaxies. Now, there’s a lot that we don’t know about how this raw fuel, raw material goes into making galaxies, you know, so hydrogen, it’s so happens; emits radiation or radio waves at the specific frequency of 1,420 Mega Hertz. So roughly 15 times the frequency on your FM dial, but it’s faint. So in order to study it from distant galaxies into this Universe, you really need a big so-called collecting area, a big bucket, very sensitive buckets. And that’s what MeerKAT is.

So MeerKAT was optimized. One of the things that was optimized for was to study hydrogen throughout the Universe from two thirds of the way across the Universe to today in our own galaxy and some of our own colleagues, including some of you are using MeerKAT.

Jacinta: [00:30:38] Yes. We have talked a lot on this podcast about using MeerKAT to study the hydrogen since that’s my field.

What are you most excited about for the future with MeerKAT discoveries?

Fernando: [00:30:49] Well, it’s funny.

Dan: [00:30:51] Without giving anything away.

Fernando: [00:30:55] No. I’m interested about everything. I remember discussing this question when I first came to South Africa back in 2015. I was thinking of taking this job and in the talk that I gave in the SKA South Africa office, I went through a bit of a history lesson with telescopes and I was showing what the Hubble Space Telescope was designed to do.

The reason why it was built, or at least a reason that someone used to convince the funders to pay the bills – to build the Hubble Space Telescope. And then when you look back at the Hubble Space Telescope 20 or 30 years later, it did do that project that it was originally intended to do rather well.

But particularly it did things that nobody had thought of. For instance, a Nobel prize was awarded for a fundamental discovery that tells us a lot about how our Universe evolves and expands and so on. That was originally made by the Hubble Space Telescope, basically. But the Hubble wasn’t designed to do that.

Nobody thought of that when the Hubble was designed. So, and this lesson is repeated throughout with other instruments, which is, if you have a relatively general purpose -really good instrument. You will make discoveries that you cannot foresee when the telescope is designed. And I’m fully convinced that this is the case with MeerKAT.

And in fact, these bubbles, I mean, these aren’t Earth shattering. They are, well maybe galaxy shattering in a sense, these bubbles, but it’s a very nice discovery. We expect there will be greater discoveries, but the points in the context of your question is that MeerKAT was not designed to study our galaxy at all.

It was actually optimized to study hydrogen in the distant universe and to study pulsars, ours as well, and a few other things, but making images of this sort isn’t really what it was optimized for, but as it happens, it’s very good at it. And this was the first, so our very first paper with a full MeerKAT was an example of a, you know, a spectacular unknown of sorts.

Yeah. A serendipitous discovery. So. I can predict, you know, scientists write all these long proposals that say we’re going to use all this telescope time to make all these great discoveries. And you know, for the most part, you end up making at least a fraction of those discoveries that you write down on your proposal.

And if MeerKAT does half of what my colleagues around the world have written down on their proposals that it will do, it will be doing very well. But in a sense, what I’m even more excited, just from a human perspective, is what I cannot think of today, the types of discoveries that it will make, like these bubbles and other things in our galaxy and beyond that we really cannot conceive of.

And you and your listeners also cannot think of. So maybe start thinking of what crazy unexpected things there might be out there and MeerKAT will probably make some of those discoveries. So 10 years from now, when we look back at what MeerKAT has achieved and continues to achieve, I expect that some of the things will have been totally unexpected.

Dan: [00:33:52] Well, we look forward to having a lot more MeerKAT episodes. So hopefully we have you back on soon to talk about some new and unknown discovery.

Fernando: [00:34:02] That would be great.

Jacinta: [00:34:03] Do you have any final messages for listeners?

Fernando: [00:34:05] Well, the messages, I understand you have listeners around the world. But this, hopefully a lot of them in South Africa, MeerKAT is a fully South African funded and largely South African designed machine.

It was designed, and it exists in the context of this much larger international project called the SKA, the Square Kilometer Array, which will start being built – we expect next year – also up in the Karoo and in Australia. But you know, I’m not South African, but I’ve been here almost four years now, and part of me starting to feel like South African, and I’m very proud of my colleagues and myself who I’ve have been involved with.

And I think every South African should really be very proud. When I go and give some presentations, talks to collaborators and so on, some of them are skeptical at first, and then they asked me three times or four times. This was really designed by South Africans? Are you sure? Like, come on. Yes, it was. It’s a South African project and it’s a brilliant project on the world stage.

It’s put South Africa out there in an area of research or South Africa hadn’t been very prominent and it’s just astonishing what clever people with vision and perseverance can do. I’m very proud of that, and I think the listeners who are South African especially should be very, very proud,

Jacinta: [00:35:19] We are very proud of South Africa.

Dan: [00:35:21] Fernando, thank you very much for joining us.

Fernando: [00:35:23] Thank you.

Jacinta: [00:35:24] I hope to speak to you again soon.

Fernando: [00:35:25] Thank you very much. So do I

outro_music: [00:35:27] music outro

Jacinta: [00:35:35] All right. How cool was that?

Dan: [00:35:36] Yeah, very cool. I mean, we’ve talked a lot about MeerKAT and about how cool it is, how sensitive it is, how, what a good project it has been. Talking about how it came in past the sensitivity as it was designed to. It’s just been an incredible project that came in on budget on time.

More sensitive than planned. It’s something really that, you know, South Africa can be very, very proud of. It’s a South African project from start to finish and it’s producing what it was aimed to do now. Some incredible science and there’s just going to be more and more and more coming out of it.

Jacinta: [00:36:12] And how often do you build something and then it ends up better than you designed it?

Dan: [00:36:17] I think never.

Jacinta: [00:36:20] It was very rare, very exciting.

Dan: [00:36:23] The things that are going to come out of it. I mean, Fernando talked about a few of them. But there’s, there’s so much that MeerKAT can do. It’s, these bubbles are one thing, as he said, this wasn’t even what they were really looking for or what the, what MeerKAT had was designed to.

Jacinta: [00:36:36] It was an uknown unknown.

Dan: [00:36:39] Yeah. Well, yeah. So it’s one of those things we were stumbling on. There’s going to be a lot more things we stumbled on that we didn’t know. But then also there’s all the science that MeerKAT was planned to do, right? You know, we’re gonna map distant galaxies, and we’re going to understand a lot more about the universe than we did.

And other objects, pulsars. There’s a lot of potential there. There’s a lot of data coming already, it’s streaming out data. And at the moment I think we, the astronomers, are already overwhelmed. We’re not even in the SKA era. We’ve got more data than we know what to do with.

Jacinta: [00:37:12] Yeah, we’ve got data coming out of pur ears.

Dan: [00:37:14] Yeah. So a very exciting time to be a scientist. And I think that, for the public too, we are gonna make some awesome discoveries from here in South Africa.

Jacinta: [00:37:22] And I thought it was really cool, the concept that if you had radio eyes, if your eyes could see in the radio instead of the optical, you would see these bubbles extending like over a huge fraction of the sky.

And if you could see, if you had Gamma-Ray eyes, you’d see things that are even bigger.

Dan: [00:37:40] Yeah, so I mean, we can see the Milky Way. Well, if you’re lucky in the dark sky, you can see the Milky Way streaking across the sky, but in the opposite direction, you’d be seeing these massive bubbles blowing out as a center.

Jacinta: [00:37:53] Oh, how cool would that be if you had like Gamma-Ray glasses or Radio glasses and you could just put them on and see the plumes?

Dan: [00:38:00] Well, let’s hope that the gamma-rays don’t get down to us.

Jacinta: [00:38:04] Look, it’s a good point. You have to be in space to see it. It’s blocked by the atmosphere. Thankfully.

Dan: [00:38:10] We’ve got to keep this scientifically accurate.

Jacinta: [00:38:12] Yeah, that’s true. No, you’re right.

Dan: [00:38:13] Okay. I think that’s it for today. I think it was a very fascinating conversation with Fernando great to have him on and I’m sure we will be having him on again soon when MeerKAT makes another big discovery. Thank you very much for listening. As always. We hope you’ll join us again on the next episode of The Cosmic Savannah.

Jacinta: [00:38:29] You can visit our website, thecosmicsavannah.com where we’ll have the transcription and links related to today’s episode. You can also follow us on Twitter, Facebook, and Instagram @cosmicsavannah. That’s Savannah, spelled S-A-V-A-N-N-A-H.

Dan: [00:38:44] Special thanks today to Dr. Fernando Camilo for speaking with us.

Jacinta: [00:38:48] Thanks to Mark Allnut for music production, Janas Brink for Astro photography, Lana Ceraj  for graphic design and Thabisa Fikelepi for social media support. Also to Brandon Engelbrecht for transcription assistance.

Dan: [00:39:00] We gratefully acknowledge support from the South African National Research Foundation and the South African Astronomical Observatory.

As well as the University of Cape Town Astronomy department for their support and keeping the podcast running.

Jacinta: [00:39:12] Yes, thank you for their new sponsorship of the podcast. You can subscribe on Apple podcasts, Spotify, or wherever you get your podcasts, and if you’d like to help us out, please rate and review us and recommend us to a friend.

Dan: [00:39:24] We’ll speak to you next time on The Cosmic Savannah.

outro_music: [00:39:29] music outro

Jacinta: [00:39:35] Dum-dum…tssshh.

Dan: [00:39:40] You need bloopers that involve you, not just me.

Jacinta: [00:39:43] But I do the editing and I enjoy making you the blooper. Yeah. We’ve got data coming out of our ears pouring out of our…pours out. Okay. That’s for the bloopers.

I know, that is gross.

Didn’t know what I was going for then.

Dan: [00:40:05] It’s not even that hot today.

Episode 21: X-Ray Binaries and Astrocomms!

with Dr Tana Joseph

This week on The Cosmic Savannah Podcast we are joined by South African Astronomer, Dr Tana Joseph who is currently based at the University of Manchester, UK. Tana holds a Royal Society Newton International Fellowship and researches things called X-ray binaries.

X-ray binaries are a type of binary star system that emit X-rays. The X-rays are produced by matter falling from a star onto an exotic object such as a neutron star or black hole.

Tana also runs AstroComms, a Science, Technology, Engineering and Mathematics (STEM) consulting and communications company. AstroComms assists STEM practitioners, institutions and policymakers to effectively leverage STEM as a driver for economic and social development.

This week’s guest

Related Links:
AstroComms: https://astrocomms.com/

Featured Image:
Artist’s impression of an X-ray Binary. One star’s outer layers are being sucked towards its companion neutron star or black hole. This releases enormous amounts of energy into space.

Episode Transcript

(By Brandon Engelbrecht)

…Intro music begins…

Jacinta: Welcome to The Cosmic Savannah with Dr. Jacinta Delhaize

[00:00:07] Dan: and Dr. Daniel Cunnama. Each episode, we’ll be giving you a behind the scenes look at the world-class astronomy and astrophysics happening under African skies.

[00:00:17] Jacinta: Let us introduce you to the people involved. The technology we use, the exciting work we do, and the fascinating discoveries we make.

[00:00:24] Dan: Sit back and relax as we take you on a safari through the skies.

…Intro music ends…

[00:00:34] Jacinta: Welcome to episode 21

[00:00:36] Dan: Today we’ll be speaking to…

[00:00:37] Jacinta: today we’ll be speaking to Dr Tana Joseph from the Jodrell Bank Observatory,

[00:00:42] Dan: which is in Manchester in the UK.

[00:00:44] Jacinta: That’s right. It’s close to Manchester in the UK, and she’s going to tell us all about x-ray binaries.

[00:00:52] Dan: And we should probably point out that Tana is from South Africa originally.

[00:00:55] Jacinta: Yes. She’s from Cape town itself. So she studied here and then she went off on various adventures around the world, and now she’s a superstar astronomer and also a small business owner.

[00:01:08] Dan: And what exactly is an x-ray binary?

[00:01:10] Jacinta: That’s a very good question. So this episode is all going to be about stars and stellar evolution, which we haven’t yet.

[00:01:16] Talk to that much about, because you and I are both galaxy people and a lot of our colleagues and conferences we go to, we talk a lot to people who research galaxies, both our own and extragalactic. But every now and again, we try and talk to someone in the stellar community, and Tana is one of those. So x-ray binaries are…

[00:01:35] So the sun is relatively rare, relatively unusual in that it’s just hanging out by itself. And we in the solar system revolve around it, but a lot of stars are actually born close together and orbit each other for the rest of their lives. And this is called a binary.

[00:01:51] And then if one of these stars is very massive, it can explode in a supernova explosion at the end of its life and what’s left at the end of that can be what we call an exotic object. It could be a neutron star, which is made of just neutrons. It’s very compact, very dense, and sometimes it’s releasing pulses of radio waves, or it could be a a black hole. And then when it interacts with the companion star, so the star that’s still alive, it’s still a normal star.

[00:02:20] Some of the outer layers of the atmosphere of this star accrete, or are sucked in towards this neutron star or black hole. And as it’s doing this there, it’s releasing a huge amount of energy often at very high energy wavelengths. So like x-rays.

[00:02:37] Dan: So these compact objects are basically devouring their sibling star.

[00:02:41] Jacinta: Yeah. They don’t eat it completely, but they, they’re kind of sucking stuff off. This other star.

[00:02:46] Dan: Just  nibble

[00:02:47] Jacinta: Just a little nibble.

[00:02:50] Dan: But, so there’s this event though, this, this little nibbling on your companion star. It’s very energetic, right? So that’s where these X rays are coming from. X-ray radiation is a. It’s very energetic radiation and requires quite a hot, energetic environment.

[00:03:05] Jacinta: Yeah. So you basically have to have something that’s very dramatic in the universe, something that’s very hot, very high powered. So this is not a quiet environment. Certainly life can’t exist near this interaction because it’s releasing a lot of crazy radiation. We’d be wiped out immediately. Yeah. So that’s why it’s, it’s quite exciting to figure out what’s going on and how.

[00:03:27] This interaction impacts the evolution of both the star and the compact object and what that leads to in the future. And then eventually leading all the way to gravitational wave studies.

[00:03:41] Dan: We should probably hear from Tana and she can explain this further.

[00:03:44] Jacinta: Yeah, she explains it fantastically. So let’s, let’s hear from Tana.

…Transition music…

Jacinta: Here with us, at the SARAO bursary conference, 2019 is Dr Tana Joseph from the University of Manchester, welcome Tana. 

Tana: Thank you for having me. 

Jacinta: Tell us about yourself. 

Tana: My name is Tana Joseph, I am an X-ray astronomer and I am originally from Cape Town currently working at the University of Manchester in the Jodrell Banks centre for astrophysics. I am a Royal Society Newton International Fellow and I am really enjoying my time in Manchester. But as the nights get longer in the northern hemisphere winter, I am glad to be here in Durban in the nice warm sunshine. 

Jacinta: I bet you are. So, Tana, you are originally from Cape Town, tell us about your path through astronomy?

Tana: In the mid-90s I decided that I wanted to be an astronomer and at that point, there was no SKA, there was no MeerKAT, there was no Southern African Large Telescope, the optical telescope in Sutherland that is really famous in South Africa. So that infrastructure wasn’t there and those resources weren’t there in the mid-90s. But with my parents’ support, I decided that this was going to be my career and did the necessary subjects at school, like maths and physics. I did my undergraduate degree my BSc. in physics at the University of Cape Town, I did my honours in physics there as well and then, I switched to astronomy at the masters level and by that point, we had started receiving SKA funding. They hadn’t yet chosen us as a joint host country of the SKA but we were busy making plans and building things, things like the KAT-7 telescope, that is also out in the Karoo and with the help of that funding and those resources I did masters in, actually galaxy surveys. So HI galaxy surveys, so I have a soft spot.

Jacinta: Really!

Tana: Yes, so I have a bit of a soft spot for HI because that was my first introduction to astronomy, with single dish HI galaxy surveys so I started out…

Jacinta: Me too

Tana: Yeah, so I started out extra-galactic and learned a lot, it was a really nice learning curve and that was in 2007 that I started and I also attended my first bursary conference and in those days it was not called the SARAO bursary conference it was just called the SKA bursary conference because SARAO was only established a couple of years ago, so this was more than 10 years ago and it’s always lovely for me to come to this particular conference and see the sheer number students the number of people that I don’t know is really exciting to me because things have really really grown so much and the community is increasing and it’s increasingly diverse and it’s increasingly young and that is exactly what you need for a big sort of legacy project that the SKA is set up to be. That you need to have a lot of young people to drive it forward and I have even said this about myself now, as a sort of technically an early career researcher still but I’m now on my third or fourth depending on how you count it post-doctoral fellowship and I have said to school kids when I do outreach talks, that the SKA is not actually for me. MeerKAT and ASKAP, the Australian counterpart of MeerKAT, the SKA precursors are for me in terms of my career and last night at the opening address the director SARAO, Rob Adam kind of echoed that. He said, when he sees the more senior people here, the SKA is not for them in terms of their career and even for me, I’m not as senior as a professor but I see MeerKAT and ASKAP as the workhorses, that’s where I am going to, do my interesting science and by the time SKA Phase 1 is done, I will be past my Nobel Prize-winning time because the thing about a Nobel Prize apparently is that you win it for work that you did before you were forty and I am thirty-five so I’ve got five more years and unfortunately that counts me out as SKA Phase 1, Nobel Prize-winning science, so I have to do it with MeerKAT and ASKAP.

Jacinta: I’ve never heard that rule.

5.00 min

Tana: Yeah, it’s apparently in the sciences anyway and I mean I can’t really begrudge anyone anything because MeerKAT and ASKAP are such ground-breaking cutting edge instruments there is going to be such exciting science, already, in fact, exciting science coming out of it. So now is the time to do that ground-breaking research.

Jacinta: Yeah, definitely. What single-dish telescope did you use for your HI studies during your PhD?

Tana: I travelled to the middle of France, to a tiny village called Nancay and I used the Nancay radio telescope which is quite an old telescope and has a really interesting sort of funny design. Back in the days when actually built this telescope, they couldn’t make a single dish that big, so they split it up into what would be sort of the equivalent of quite a big telescope. Much bigger than any of the MeerKAT telescope dishes, individual dishes. Not quite Green Bank telescope big, which I think is just over a hundred metres, so not quite as big as the Effelsburg telescope or Green Bank telescope but sort of on that kind of scale, but they couldn’t figure out, they didn’t have the engineering capacity to make a single dish. It’s what called a, it’s not quite a transit telescope but it’s made up of, sort of a curve bit that is a section of a sphere and then a few tens of metres away on the other side of the field is the flat steerable mirror part and then the focus is in the middle of that and it’s on a curved railway track, so if you want to really focus you, you need to actually move the focus. Yeah, it is a really interesting design and I got to go out there as a part of my masters. Luckily I spoke a bit of French because I was in a part France in a small village where no one spoke any English so everything had to be in French and I ate the most delicious authentic french food it was fantastic and every night my supervisor and I, who was a much older man had a daughter who was about my age, we would sit and have our dinner and they would give us a bottle of wine. So we would be drinking this, what I would call fancy French wine but to them, I suppose it was just plonk and so yeah it was a very sophisticated experience getting my data.

Jacinta: Wow, that sounds a lot more like a sophisticated, romantic kind of experience than I had when I was doing my PhD with single-dish telescopes. I used the Parkes telescope in Australia, in rural Australia and I spent it sort of fighting off locusts plagues. But I don’t know if they were locusts but something like that.

Tana: So we had no locusts, but there was a bit of a warning, we were told to watch out for wild boar so its proper like wooded area of France, a bit of the Asterix and Obelix kind of vibe about it. Yeah very rustic and we would, they would just like, just kind of don’t go into the woods after dark, there is known to be some wild boar around and they could seriously hurt you.

Jacinta: Oh dear

Tana: Yeah, so a very interesting experience part of thing where astronomers or other academics say oh I love to travel, I see different parts of the world and you think of France and oh it’s not that exotic but that is because you are thinking of Paris because everyone knows the Eiffel Tower, everyone knows the Louvre but very few people get to go to these tiny villages like I did. I was, yeah, I was very happy to have that experience and all that delicious food.

Jacinta: Oh yum, I am getting my tummy starting to rumble thinking about it. Okay so you started off in HI kind of astronomy area and you mentioned that you now work in X-rays, which is a different part of the electromagnetic spectrum and on this podcast, we have spoken a lot about radio astronomy because of you know, obviously MeerKAT here in South Africa and we speak a lot about optical because of SALT but we rarely have spoken about X-rays, so just tell us sort of, why X-rays and what you can see with them.

Tana: So X-rays are on the very high energy end of the electromagnetic spectrum and it is what we call penetrating radiation which, if you are familiar with X-rays from getting them at, in a medical sense at hospital to look at your broken bones, it makes sense that it is called penetrating radiation because the X-rays go right through your body and they are absorbed differently by your skin, by your muscles and by your bones and that is how you build up an image of whats inside and so X-rays coming from outside the Earth are actually absorbed by the Earths atmosphere, cause if they actually were to reach us, they would be extremely damaging and harmful to our bodies because they go right through and would be sort if you think about ultra-violet rays causing skin cancer, X-rays are much more energetic than that so it would be a real problem. So in order to observe X-rays and observe the Universe in X-rays we actually have to put the telescopes and detectors outside the atmosphere so they are satellites, they are X-ray satellites, so I get to use space telescopes in my X-ray research and another way to sort of to think about X-rays is, it comes from things that are incredibly hot so about ten or twenty million degrees and when something is very hot like that it is also an indication of something that is very energetic, very powerful very strong forces and interactions and processes so you are looking at things where there is strong gravity strong magnetic fields, all that kind of stuff. What you see in X-rays is the energetic Universe, things like black holes, neutron stars, pulsars, in particular, I study X-ray binaries which are stellar-mass black holes. So black holes that you get from exploding massive stars after they go supernova or a neutron star and they have some other star orbiting them called a donor star or companion star and the donor star actually “donate” its material to the neutron star or the black hole and that process is called accretion. So obviously the star is not actually donating it is happening under the force of gravity, the strong gravitational field and as that material gets dragged off the donor star and onto the neutron star surface or into the black hole it heats up and there is a lot of friction in there and it heats up to about ten to twenty million degrees and then it starts to glow in X-rays and that’s what we or that’s what I study or detect with my space satellites and what’s great about X-ray binaries, they are called X-ray binaries only because that’s the wavelength that they are brightest in but they are actually multi-wavelength objects. So X-ray, the process the physical process that happens in X-ray binaries give off a lot of X-rays they also give off a lot of radio waves and optical light and in some cases gamma-rays as well. So it is a nice multi-wavelength object and I actually use a lot of multi-wavelength data in the study of these and now that we have gravitational wave detectors, we are opening up a new way to explore these binary systems. So systems that would normally be dark in the electromagnetic spectrum like two neutron stars orbiting each other or two black holes or a neutron star and a black hole orbiting each other. So at some point, those sources probably use to be high mass X-ray binaries what we call High Mass X-ray binaries and there is a lot of interest now in the cool cutting edge gravitational wave community to go back, take a step back and say but where do we actually get these double black holes or double neutron star or neutron star black hole systems, you get them from X-ray binaries. So we are trying to figure out those exotic sources by looking at the progenitor sources which is High Mass X-ray binaries. So just to explain, we have this funny thing in X-ray binary research that we classify X-ray binaries by not the mass of the neutron star or the black hole but actually the mass of the donor star. So when I say a high mass X-ray, I mean a neutron star or a black hole that is in a binary with a massive star, so a star that is greater than ten times the mass of our sun. Low mass X-ray binary which is actually my main focus is where the donor star is about twice as massive as our Sun and less. So our Sun is a low mass star and then that range in between the two to ten solar mass range you would have intermediate-mass binaries but they are very short-lived and there are actually not that many so we tend to sort of not consider them when we studying populations because there are only sort of a hand full that are known. So that is how you classify X-ray binaries, not by the black hole or the neutron star but by the companion star.

15min

Jacinta: So why is it important to study X-ray binaries, in particular, low mass X-ray binaries and what are you working on at the moment?

Tana: Thank you for bringing up those questions, it’s a fantastic question. What’s great about low mass X-ray binaries is that you get them sometimes in these configurations with a black hole where you have the donor star, donating its material to the black hole and then you get these radio jets coming out and they are tiny analogues of active galactic nuclei where you have a supermassive black hole at the centre of a galaxy and it also got these jets coming out: radio jets, sometimes X-ray jets, sometimes optical jets. These tiny low mass X-ray binary analogues are called micro-quasars and what’s really useful about black hole physics or that we think how black hole physics works, is that it is scale-invariant. What that means is that whether you are looking at a ten solar mass black hole in a micro-quasar or a ten million solar mass supermassive black hole at the centre of an active galactic nucleus, the physics is the same and so the issue comes in with time scales. The bigger your object that you are looking at, so if you are looking at supermassive black hole, the longer your time scales so these AGN are bright and you can see them at really really far distances and that is really great. But the time scales on which the physical processes happen, happen on the scale of centuries and millennia and so that is obviously much longer than a human, not just a human life but a human civilization whereas the micro-quasars, the time scales involved are minutes, days, weeks, months so very much more manageable timescales. You can use the low mass X-ray binaries, well the microquasar low mass X-ray binaries, to learn about faraway distant galaxies to kind of probe the physics, the complicated physics that happens in these AGN which is very exciting. Another example again with gravitational waves, with multi-messenger astronomy why low mass X-ray binaries are particularly interesting we actually think that within in these structures called Globular clusters, which are very old, so when I say very old I mean Giga years old, some of them can nearly be as old as the Universe itself. These very old, very dense compact spherical clusters of stars that orbit galaxies so they are called globular clusters and inside them, there are low mass X-ray binaries and there is this particular kind of low mass X-ray binaries we call ultra-compact binaries with a black hole and say a white dwarf and they are orbiting each other and our calculations suggest and the theory suggests that these low mass X-ray binaries will be sources of gravitational waves that we should be able to detect, with future space-based gravitational wave detectors, particularly one called LISA. Laser Interferometry Space, I can’t remember what that A stands for now, but I got most of the way through that acronym though and so LISA will be, LISA won’t be sensitive to the same thing that LIGO is detecting, so these far away quite heavy double black holes or the neutron stars quite far away, but much lighter systems, but much closer in, so we are talking about globular clusters that are orbiting our own Milky Way galaxy and so now there is a lot of again a renewed interest in low mass X-ray binaries because of the gravitational wave connection in trying to find these systems ahead of time. So we have a priori knowledge of them in the electromagnetic system and then adding on the gravitational wave information once LISA comes online and what’s really nifty about LISA is that it should be coming online roughly the same time as SKA Phase One, which is the MeerKAT expansion. So they should be contemporaries and I think that is really going to revolutionize the study of X-ray binaries. So my talk here at the SARAO conference 2019, is about expanding, not just expanding our X-ray binary work to gravitational work but actually how electromagnetic studies of, sort of the more traditional studies of X-ray binaries can actually provide really important information going forward for things like LISA for example. One of the issues that you have with LIGO and LISA is this issue of localization. Narrowing down where on the sky these things actually came from so you can try and see if there is a galaxy there or you can try and point other telescopes at it. So if you already have information, say an ultra-compact X-ray binary, low mass X-ray binary in a globular cluster, because you saw, you can have some candidates, you know exactly where it is because you have really good localization with something like MeerKAT and once LISA is built and these things actually start giving off detectable gravitational waves in the LISA band, then we have a wealth of information leading out of that. We have a priori data then you add that to the gravitational wave data and so basically I am trying to showcase the fact that gravitational waves are what hot’s right now in astronomy but electromagnetic telescopes so traditional telescopes aren’t just useful as follow-ups but can actually be providing precursor information, so we can actually inform what they look at and what science they do because we have said perhaps a list of candidates already and I think that is really important.

Jacinta: Yeah, I was going to ask when LISA is going to be expected but you already answered that and I was wondering whether it would be coincident with the SKA, which you said that it is. So it’s just going to be an amazing revolution in astronomy and I can’t wait to hear what we are learning about. In the meantime what are you working on now?

Tana: At the moment I am on the Large and Small Magellanic Clouds so the nearest, our nearest galactic neighbours and for those of you in the southern hemisphere, of course, you can see them with your naked eye if you are in a sufficiently dark place and unfortunately if you are in the northern hemisphere you can’t see them at all, so that is a good enough reason to come to the southern hemisphere and these Magellanic clouds are really useful testbeds in terms of astrophysics because we know exactly where they are in terms of the distance but they also near enough that you can resolve the stellar components, you can study tidal interactions because these galaxies are really small compared to our Milky Way so they are being tidally disrupted by each other because they are quite close to each other but also by the much larger Milky Way so there is a lot of tidal interactions. They have a very low metallicity and I am not sure if the listeners out there know this, another quirk of astronomy is that basically in astronomy we have Hydrogend and we have Helium and all other chemical elements are called metals.

Jacinta: Chemists hate that.

Tana: Yes, my sister is studying chemistry and she gets very frustrated when I just say metals and I just throw it out there. So these two galaxies the dwarf galaxies, the Magellanic clouds have a very low abundance of metals compared to our sun or compared our galaxy the Milky Way and so in that regard that actually makes them similar the conditions in the early Universe, where there were fewer metals because there were fewer stars to enrich the Universe. So if you want to study things that are dependant sensitively on how much metal or how many metals, or the metal abundance is like for instance the evolution of very massive stars, so stars that are greater than a hundred solar masses depends very much on the metallicity components and you can study that really well in the Magellanic clouds and these very massive stars are exactly the kind of stars that we think for these massive black holes that LIGO has seen. How do you get fifty solar mass black hole because usually stars that we see in our local environment go up too about maybe forty solar masses, there are few that are bigger but we actually discovered in the Large Magellanic Cloud, a population of stars with masses of a hundred and fifty up to three hundred solar masses and that is only possible when you have low metallicities. So that is just one example of why the Magellanic clouds are a really good testbed to study the kind of things that give you LIGO sources and they also have a lot of high mass X-ray binaries which I said earlier on, would be the progenitors of these LIGO type sources. So they have everything that you need, they have the low metallicity, they nearby, they have a lot of truly massive stars, they have a lot of high mass X-ray binaries and so you can put all of that together and you can study a lot of pre-gravitational wave sources, you can study the physics of the thing that goes into that and that is what I am doing right now. So I have used the ASKAP telescope along with a huge team of people of course, all over the world to survey the Small Magellanic cloud and I also have some data on the Small Magellanic cloud from MeerKAT and we are putting all this together trying to find out as much as we can really about these galaxies and really delve into what’s in there, how did they get there, how did they grow and change an how did they change their environment and there is so much work to do which is always great because if we knew everything, we wouldn’t have scientist. So it is a really exciting time for me to finally get my hands on some SAK precursor data.

Jacinta: Yeah, I mean that is really really exciting so ASKAP, of course, being the radio telescope recently built in Western Australia, the counterpart to South Africa MeerKAT and you got data from both which is incredibly exciting. Do you think this may one day help us to understand how supermassive black holes are formed, supermassive as in millions to billions of times the mass of the Sun?

Tana: So that is a slightly awkward question actually because there is something called a mass gap, I guess you call it in astronomy. Where we know that supermassive black holes exist because we observed them and we can estimate their masses and we know that, what we call stellar mass black holes and their masses go up if you include the LIGO masses they go to just about eighty solar masses, eighty times the mass of our Sun and some as light as maybe five or six or seven times the mass of our Sun and so that leaves a huge gap their so basically between a hundred solar masses and a million solar masses there is nothing in terms of black holes and that is the region we call intermedite mass black holes amd so that is something that we think forms in the early Universe so LIGO might be able to help with that because what could be happening is you could have these LIGO sources where you have a fifty solar amss black hole and a fifty solar mass black hole and they merge and you get say a hundred solar masses but that would happen in the very early Universe and we would know more about that once we know more about where these intial heavy mass black holes came from, but it still does not really fill the mass gap in. The reason why this is awkward is because we think that intermediate-mass black holes are sort of what we call the seed black holes from which supermassive black holes via accretion. So you get this intermediate black hole, say it’s about a hundred thousand solar masses and then over time it accretes or draws mass onto it from a galaxy around it and it grows and that is how it ends up as a supermassive black hole. But we can’t find these intermediate black holes and there are a few candidates, one or two really good candidates but until we get a mass estimate, we won’t see anything and this kind of ties into, well what I will be talking about in my talk. Where we trying to, there is no consensus yet whether the Large Magellanic Cloud has a central black hole or not. So there a black holes at the centre of most massive galaxies, but these are dwarf galaxies, the Magellanic clouds so if there is a black hole at the centre, given the size of the Magellanic clouds, it’s probably going to be an intermediate-mass black hole and this is something we could possibly detect with LISA if we have stars close enough spiralling in, in what we call an extreme mass ratio in spiral. So the extreme mass ratio comes from the fact that the intermediate-mass black hole in the LMC say about ten, no say a hundred thousand solar masses and then it would be dragging in stars that are normal steller masses so between one and twenty solar masses so that is a huge ratio of masses, ten thousand versus one basically or ten thousand or hundred thousand versus one hundred thousand verses ten and that will actually, the inspiral of those stars into this intermediate-mass black hole will give rise to gravitational waves that LISA should be able to detect and what’s great about these in spiral scenarios is that the theorists are saying before they spiral in like that there will actually be electromagnetic radiation given off, from the radio all the way to the X-ray and in the southern hemisphere we have two of the most powerful radio telescopes they can easily and very sensitively observe the Large Magellanic Cloud and look for signatures of these extreme mass ratio inspirals and this is where the localization comes in, that I spoke about earlier because LISA, LISAs’ localization, the way it is being set up is not going to be that good. So we would massively benefit from having say ASKAP and MeerKAT working together finding these radio waves coming from these stars spiralling into this potential intermediate black hole in the Large Magellanic Cloud and using the very good accuracy, the spatial accuracy of these radio telescopes and then nailing down where this black hole actually is and then LISA will be able to kind of point at it much more accurately and so this is sort of the fantastic synergy of multi-messenger astronomy, where the electromagnetic components, the gravitational waves and maybe even things, we might even see neutrinos as they spiral in. Cause multi-messenger isn’t just gravitational waves and electromagnetic waves, it’s also neutrinos, cosmic waves, cosmic rays, it’s even meteorites and comets and all of that because these are all messenger particle, they all give us information about the Universe but they don’t always apply to every system. So that’s something that we hoping to start to get information on when we start observing the Large Magellanic Cloud.

Jacinta: Wow so I did, I did honours research on the Magellanic Clouds and the Magellanic Stream, but I had no idea that something so close could give us so many clues about the very early Universe, which in astronomy terms is very very far away from us so that is really amazing. But not only are you a very successful astrophysicist, you also own your own company.

Tana: Yes, I do, I started my company called AstroComms, October 2018, so just over a year ago and it was born out of all of the outreach and consulting work that I had done over the years as a postgraduate student and as a post-doctoral fellow and I realized that there is actually a demand and a value for this outside of just a strictly academic environment. So my first client was sort of a tech startup company called MeasureMatch and they hired me to give a talk about big data in science because they are also a data analytics company and their idea of big data is laughably small to what we work on in the sciences. So it was just really nice to just sort of give them insight into, give a broader context for sort of where what big data is, where is it going, what’s actually at the cutting edge. Like the work that do in the private sector is thought of as more interesting and useful but a lot of the tools that come from actually handling that come from the sciences, where we have to have the best equipment and the most optimized algorithms and all that kind of stuff and it filters down into industry so I was invited to give a talk about that and they actually paid me and it was great and I have had several other clients so far. I think my favourite one so far, they actually made me sign a non-disclosure agreement so I can’t say too much was to be a technical, basically the technical consultant for a sci-fi TV programme.

Jacinta: What!!

Tana: Yeah so like Kip Thorn, the Nobel Prize winner Kip Thorn who did interstellar, he did the black hole stuff for interstellar and made sure it was really accurate, so basically like that but without, if you don’t have a Hollywood budget, if you don’t have Kip Thorn Nobel Prize-winning money, I do the same thing but much cheaper. So yeah all sort of things like that speaking at festivals and so on. So the mandate basically of AstroComms is that it is a STEM, so the science, technology, engineering and maths consulting and communications company. So anything whether it’s just input on policymaking or for curriculum, yeah checking over curricula or curriculum development to science consulting of the media or for the creative sectors and then also giving talks, I really enjoy giving talks. I really enjoy and I am very privileged to be working with the SKA programme, as long as I have and being able to sort of showcase and highlight how far the programme has come, all those exciting things that have been happening especially in an African context. I love going out and dispelling Afro-pessimism so this idea that Africa is such an under-developed place, such a place that is somewhere where you just extract from and no one is actually building anything up and it is really great to go be able to dispell those myths and those negative connotations around Africa and say you know we are building cloud computing centre, we are on the cutting edge of astronomy, we are a global hub for astrophysics research and it’s not just in South Africa it’s actually spread around several countries across the continent and this is what we are doing, these are the fantastic young people that are coming through and being able to talk about that and I get paid to do that, I get paid to spread the word and change peoples perceptions of this fantastic continent that we are on and I think that’s something that I really try to focus on and put at the heart of the work that I do through AstroComms and people are really interested, people want to hear these good news stories. They want to hear things are changing and I always get really positive receptions about that and so I hope that there will be more gigs like that in the future and yeah just so open to all sort of ideas where technical input is needed or a science perspective is needed especially from someone still very much in the research community.

Jacinta: This is a fantastic idea, but it’s still quite unusual in our field. I think you are maybe one of, I don’t know how many but I have never actually heard about it before. How do you make this work, is it still currently moire of a side hustle that you do in your “spare time”  or have you incorporated this into your sort of your, I don’t know what you would call day job perhaps? 

Tana: I am that the moment, it is very much a side hustle but the idea is that I have got, I’ve set myself a fice year plan to grow the company to a point where it can be my day job and that sort of gives me exactly enough time, I think to wrap up my work MeerKAT and ASKAP because I feel now is not the time to leave the sciences, I have waited so long, the telescopes are here they doing amazing work, they are exceeding even the expectations of the people that built the telescopes. But at the same time, the work that we are doing with the SKA precursors is providing so much for me to actually talk about so when people invite me I stuff to talk about.; I can talk about the big data aspects, I can talk about the development aspects, I can talk about the political aspects because of what SKA is as well as all of this cutting edge science and engineering is also a beautiful example of science for diplomacy. Where you can pull resources and get a lot of people together from very different backgrounds, people who or places, people and places that weren’t necessarily engaged in sciences and get them all together and get them all working on a common goal that will enrich the continent but also bring a lot of opportunities to communities that weren’t always necessarily engaged with STEM and that is the kind of thing that I get to have an inside, an insiders knowledge of and sort of evangelise about and so I feel for me right now those sort of things go hand in hand. So it is a side hustle, AstroComms is the side hustle at the moment and I am starting to get to the mid-point of this five-year plan where I am going to have to, the tipping point is going to come where I am going to have to devout less time to my research and more time to the company and navigating that is going to be tricky, I’m not quite there yet. But the companies profile is being raised and I am getting a lot of interesting work and my, the people I work for are extremely supportive of this, so if I need to take time off sometimes to go give a talk that’s something they are aware of and I do a lot of my work remotely as well, a lot of it via email or on skype, telecons things like that, with the interconnectivity that we sort of, that we are in the modern-day world that is really possible. So it’s not as tricky as it would seem because people are happy to jump on skype and or record like in fact this is like a podcast that I am doing right now and I am sitting across from you, I did a podcast a couple of months ago where I was in Manchester and the guy who runs the podcast is in Pretoria and we just did the podcast over skype, we just did a skype conversation and so this is all these sorts of mod-cons make it much easier to collaborate with people all over the world, just pop something in, in an online repository or google docs, Evernote and you can really time editing sessions even if you are thousands of kilometres apart.

Jacinta: Yeah, you are absolutely right the world is a lot smaller now than we sort of think it is. So I think that this is absolutely inspirational and congratulations on getting this far and good luck in the future, you sort of paving the way for others and the rest of us to sort of go down these paths. We should go back into our session on the conference soon, but o you have any final messages for the listeners?

Tana: I would say, stay tuned to this podcast, because of they are doing fantastic work, showcasing all the cutting edge sciences that is happening, especially interviewing young people and also stay tuned because I would like to give more updates on my company and what I am doing. I would say to any young people listening that, things may sound outlandish when I decided I wanted to be an astronomer in 1995 it sounded ridiculous and outlandish but what people need to realize is, if you are in high school now, in five or ten years time, jobs will exist that don’t exist now. I remember writing a forward for a science magazine in 2013 and I used the phrase, I said something about a newfangled thing called data science and now data science is so pervasive, there is som many astronomers that go into it data science after they’ve concluded there research careers and that didn’t exist ten years ago, there was no such thing as a data scientist. Big data wasn’t something that was talked about the way it is now. The fourth Industrial Revolution, getting people really excited, things like cryptocurrency. These things didn’t exist in our parents time, they didn’t exist when I was in high school, the telescopes I work on now didn’t exist. Some of them didn’t even exist when I was already doing my post-doctoral, oh sorry my post, yeah my post-doctoral studies because MeerKAT was only completed in 2018 and I already had my PhD for five years at that point. So things change at a ridiculous pace and you will equip yourself well too not fix on something necessarily that you want to study because it might not exist by the time you finish your studies but be open-minded, be flexible, study things that are sort of future proof so things like coding, I would say languages because people often think that STEM is the way forward but you need the mix of humanity so study languages because you ever know when you might get shipped out to the middle of France to a village and someone comes to tell you to be careful of wild boars and you might not be able to understand them so it is a safety issue. So I would say, yeah study languages, even if you are South African and you want to stay in South Africa, yeah but you might have to go be a professor at the University of Venda, maybe learn some Venda because perhaps you only speak Afrikaans and isiXhosa, you never know. So yeah, just be open to learning experiences and one thing I learnt from academia is that you never stop learning, I haven’t sat in any formal exams in many years but I am constantly doing online courses, attending seminars and so on. So just never stop learning, be curious and just because your dream job does not exist now, does not mean it won’t exist in five years time.

Jacinta: Brilliant so where can people find you and your company?

Tana: They can find us on Facebook, there is the AstroComms Facebook page. They can find us on Twitter, so on Twitter, it’s Astro_Comms and then online their website is astrocomms.com and yeah, all the information you want on there, drop me a line, we respond very quickly if you have any queries about giving talks or any input that you want just to give an idea of what we do. I am always happy to talk to anyone really who wants to listen.

Jacinta: This has been absolutely fascinating. Thank you so much for speaking with us today Tana and doing it pro-bono.

Tana: Thank you again for having me, it was great.

…Transition music…

[00:42:21] Dan: Okay. Well, thank you very much for the interview.

[00:42:23] Jacinta: Yeah, it was awesome talking to Tana, she’s an amazing speaker

[00:42:27] Dan: and some interesting stuff in there. A lot of interesting details about x-ray binarys and gravitational waves, exciting projects like LISA, which is incidentally the Laser Interferometer Space Antenna.

[00:42:38] Jacinta: Ah, very good.

[00:42:39] Dan: So, an interferometer, gravitational wave interferometer, much like LIGO, which is currently operational, but up in space.

[00:42:47] Jacinta: So cool. Launching a gravitational wave detector into space.

[00:42:51] Dan: And I think that LISA is currently planned for 2034 so it’ll be, it’ll be coming online about 10 years after the first SKA phase comes online.

[00:43:02] Jacinta: So if anyone who’s listening is interested in becoming a gravitational wave astronomer, now’s the time. Well, by the time you’re trained, you’ll be ready to use LISA.

[00:43:11] Dan: It’s a very sexy science, only only in the last five years since we discovered them for the first time. Right? Yeah. I think the, the recommendation when we were doing our undergraduate was don’t you dare it into gravitational

[00:43:22] Jacinta: wave astronomy

[00:43:22] Mmhmm I heard exactly the same thing. There’s been no detections. We don’t know when the detection will be. Yeah. And lo and behold,

[00:43:31] Dan: Ah man, those guys got lucky

[00:43:33] Jacinta: They did. Well, they worked very, very hard and were very patient for it.

[00:43:37] Dan: That’s true, that’s true.

[00:43:38] Jacinta: Okay. So back to Tana’s interview. I, I thought it was really interesting to hear about microquasars, which is where the black hole or whatever it is, is accreting from the companion star and then releasing energy, jets of radiation in a very similar manner.

[00:43:54] To quasars, which is a type of AGN, and I study these AGN, these active galactic nuclei. So I was really interested to hear how we can see these, these much smaller scales and of the same phenomena as these gigantic scales with the supermassive black holes that I study. Why we want to do that is because then we can see the variation on human lifetime timescales, which is great because we just can’t live long enough to see these timescale changes in the big AGN.

[00:44:22] Dan: Yeah. It’s very cool. Like these, yeah. Like you say, micro quasars from micro black holes.

[00:44:28] Jacinta: Yeah. The universe scales. It’s really cool.

[00:44:31] Dan: Yeah. And the I, the other interesting thing obviously that Tana spoke about was her, her company.

[00:44:37] Jacinta: Yeah Astrocomms.

[00:44:38] Dan: Yeah. It’s pretty cool. I was very  impressed to see how these skills were transferable to other realms of life, the interest from data scientists, big data firms and things, and in what astronomers are doing, because in a lot of ways we are moving these fields forward in not just astronomy, but in terms of dealing with big data.

[00:44:59] We’re at the cutting edge.

[00:45:00] Jacinta: Yeah, absolutely. I thought her initiative is absolutely fantastic and I hope that we see more of these sorts of things in the future, and especially giving the opportunity for those researchers who also want to do communications work to receive fair pay for that and therefore allow them to do more of this, which, which you know.

[00:45:19] Ultimately, I think helps society and the movies.

[00:45:22] Dan: Yes. Well, I mean, we all want to advise on a movie. Sit there, watch

[00:45:26] Jacinta: the dream!

[00:45:27] Dan: Yeah it is the dream. I mean, every nerdy astronomer’s dream to be the advisor on some sci-fi movie.

…Outro music begins…

[00:45:36] Jacinta: Cool. All right. Well, I think that’s, that’s it for today.

[00:45:40] Dan: Yeah. Thank you very much for listening.

[00:45:42] And we hope you’ll join us again on the next episode of the cosmic Savannah.

[00:45:45] Jacinta: You can visit our website, thecosmicsavannah.com where we’ll have links related to today’s episode. You can also follow us on Twitter, Facebook, and Instagram @cosmicsavannah. That’s Savannah, spelled S. A. V. A. N. N. A. H.

[00:45:59] Dan: Special thanks today to Dr Tana Joseph for speaking with us.

[00:46:03] Jacinta: Thanks to Mark Allnut for music production, Janas Brink for astrophotography. Lana Ceraj for graphic design and Thabisa Fikelepi  for social media support.

[00:46:12] Dan: Also to Xola Ndaliso and Sumari Hattingh for transcription assistance.

[00:46:17] Jacinta: We gratefully acknowledge support from the South African National Research Foundation and the South African Astronomical Observatory to help keep the podcast running.

[00:46:26] Dan: You can subscribe on Apple podcasts, Spotify, or wherever you get your podcasts, and if you’d like to help us out, please rate and review us and recommend us to a friend.

[00:46:34] Jacinta: And we’ll speak to you next time on The Cosmic Savannah.

…Outro music ends…

[00:46:46] Welcome to episode 21.

[00:46:50] Dan: 21 today. Happy 21st you know, it’s a thing.

[00:46:55] Jacinta: Oh like 21st birthday

[00:46:57] Dan: Yeah. I don’t know if that’s every culture that, you know, every culture has a different age.

[00:47:03] Jacinta: I think it used to be you get the keys to the house.

[00:47:06] Dan: Yes. But I mean, that might be sort of British, descendants of British.

[00:47:11] Jacinta: Well, we’re all from Commonwealth countries.

[00:47:14] Dan: Well, not all of us. Just the two of us.

[00:47:17] Jacinta: Yep. Everyone in this room… Welcome to episode 21

[00:47:24] Dan: I got nothing.