Episode 24: HIRAX

with Prof Kavilan Moodley

Episode 24 features Professor Kavilan Moodley who joins us to discuss another exciting project in radio astronomy in South Africa, HIRAX!

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a radio telescope array that will map nearly all of the southern sky over a frequency range of 400 to 800 MHz. The primary goal of HIRAX is to measure baryon acoustic oscillations (BAOs): these are remnant ripples in the distribution of galaxies that originate from primordial sound waves that existed in the early universe.

This can be used for charting the expansion history of the universe and for shedding light on the nature of dark energy.

All-sky map of the Cosmic Microwave Background temperature as obtained by the Planck space telescope.  Credit: ESA
A Rock Hyrax or “Dassie”

This week’s guest:

Episode Links:
HIRAX: https://hirax.ukzn.ac.za/
Planck and the CMB: https://www.esa.int/Science_Exploration/Space_Science/Planck_overview

Featured Image:
The HIRAX Prototype dishes at the Hartebeesthoek Radio Observatory, South Africa

Transcription – By Sumari Hattingh

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

Jacinta: [00:00:07] 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: [00:00:16] 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.

Hello. Welcome back to episode 24

Dan: [00:00:40] yeah, welcome back.

Jacinta: [00:00:41] Yeah, Dan’s still on Skype. How’re you doing over there?

Dan: [00:00:45] Yeah. All right. Locked in the house with little kids. So if you hear the kids in the background, you know, apologies for that.

Jacinta: [00:00:52] Yeah. And I’m still in my blanket fort and I have no little kids here, so I just made one. I have no excuse. We’ve expanded it now it’s got two rooms.

Dan: [00:01:01] Do you stay in it even when you’re not recording?

Jacinta: [00:01:05] Yup. And we’ve added fairy lights now as well. All right. So what are we actually going to talk about today?

Dan: [00:01:12] We are joined by Professor Kavilan Moodley, who is from the University of Kwa-Zulu Natal, who you actually interviewed at the South African Radio Astronomy Observatory Bursary Conference, and he’s going to be talking to us about dark energy and an instrument they they’re building called “HIRAX”.

Jacinta: [00:01:30] Yeah, exactly. So, as you said, I was at the South African Radio Astronomical Observatory – SARAO – Bursary Conference in December last year, the start of December, which was held in Durban, which was really great to go visit because I haven’t had much of a chance to explore South Africa yet. Just Cape Town and a few other places.

But, so Durban was really cool. And, it’s more or less like the South African National, like annual conference, of Radio Astronomy. And so there’s radio astronomers there from all over the country. So it was a great opportunity to get some interviews with some people, not from Cape Town. And Kavi is one of those. He’s the Professor at the Department of Astronomy UKZN, and he’s one of the people leading the charge in building a new telescope called HIRAX.

Dan: [00:02:20] Yeah, we’ve spoken a lot about MeerKAT; we’ve mentioned a couple of the other instruments, which are happening….at the SKA. But in addition to MeerKAT, there are all of these other instruments which are also getting built, which have different little niches that they work in.

They work in slightly different niches. They look at different things in space and different frequencies, different wavelengths, and have different science cases. This is one of those different instruments, which is also going to be built in South Africa.

Jacinta: [00:02:52] Yeah, so it’ll be made of 1000 dishes and they’re each going to be six meters in diameter. And HIRAX stands for the Hydrogen Intensity and Real-Time Analysis eXperiment. So another contrived acronym from astronomers.

Dan: [00:03:11] It’s quite a fun one because if you don’t know what a hyrax is; a hyrax is a little, well, it’s not a rodent. But you can think of it as a rodent – it’s a little thing that looks a bit like a bunny, but doesn’t have long ears. It’s brown, and they exist here in South Africa. They run around on rocks and on mountains and things, and they’re very sweet, and we call them “dassies”. But their proper name is a “hyrax”.

Jacinta: [00:03:41] Yeah, and it’s a super cute logo with a little, a little dassie on it for those from Australia. It kind of looks like a marsupial, even though it’s not; like a little quokka that’s on, like only on all fours and doesn’t stand up. So that’s how I would describe it. Well, we’ll put a picture on our website.

Dan: [00:03:59] The other thing that is always said about a dassie or a hyrax is that its nearest relative is an elephant. It goes all the way back on its own branch, all the way back to the common ancestor of the elephant, and the hyrax, which is pretty strange.

Jacinta: [00:04:14] That is strange. The dassie can be found in the Karoo and the Karoo is where the telescope is built. So we’re looping back to astronomy there.

Dan: [00:04:23] Yeah. And then, as you said, there are thousands of these little dishes and they’re six meters across, so they’re not as big as the MeerKAT ones, which are 13 and a half meters across.

And they’re also a lot simpler. So they don’t have the same demands in terms of the surfaces or the instrumentation. And that means that it’s a very cheap experiment. And we can build houses with these things, for a fraction of the process; a MeerKAT dish.

Jacinta: [00:04:51] Yeah, exactly. But it’s not built yet. Just like the SKA is not built yet. There is a prototype that’s somewhere near Johannesburg, I think.

Dan: [00:04:58] Yes, Hartebeesthoek. The original Radio Astronomy Observatory in South Africa was in Hartebeesthoek, which is just outside Pretoria in South Africa, and there’s a large radio dish there, but now there’s the prototype for the HIRAX, and that’s just to test the instruments.

To try and get a concept together of what it’s gonna look like and then use that to try and raise funding to actually build this thing.

Jacinta: [00:05:28] Yeah. And other than the dishes themselves, one of the main differences between HIRAX and SKA is that the HIRAX dishes are all going to be kind of in a high density, small area, so they’re all going to be clumped quite close together.

Now, you might remember that radio astronomers always talk about baselines, which is the distance between two of these dishes and short baselines mean that the dishes are closer together. If you have dishes closer together, your telescope is more sensitive to larger scale, so you can see things that are larger on the sky.

Whereas if you have, your telescopes are very far apart, long baselines, they’re more sensitive to things that are small on the sky; small structures. But HIRAX wants to see the largest structures on the universe, and that’s why it’s got a high density of very short baselines. And they want to see large scales because a lot of the science case for this telescope is cosmology.

So I don’t know Dan. Well, so Kavi does explain that a bit, but it’s kind of, well, I guess it’s the universe on the larger scales. And I guess we need to start from the Cosmic Microwave Background or CMB in order to explain that. So, Dan, do you want to explain what the CMB is?

Dan: [00:06:43] So I’ll, I’ll take a stab. So cosmology is basically the study of the very largest scales, as Jacinta said, we’re not looking at individual galaxies. We are looking at the clusters of galaxies and beyond that supercluster – how the matter in the universe is distributed on the very, very large scales – are these clusters, there’s voids where there’s no galaxy.

And why is the matter distributed like that? What you want to do is, see where these large dense regions or under dense regions formed from. Where did they originate from? Why is there more matter in one place than somewhere else? And one of the ways we can work that out is by measuring this Cosmic Microwave Background.

If you look in the microwave wavelength or frequency, you can see all around the earth, and this has been mapped in quite a lot of detail, first led by Kobi satellite, but most recently by the Planck satellite. And everywhere you look there is microwave radiation, which is coming from the very, very early universe, and it has tiny fluctuations in terms of the color or temperature of that light. And those tiny fluctuations make up what’s called the Cosmic Microwave Background and those tiny fluctuations are the hint. as to why some regions will be dense and some regions will be under dense. So by mapping this very early universe and these fluctuations, we can see where matter would fall and on what scales – where it comes from and in what form; in what scale. So we can measure in quite a lot of detail what sort of scales the fluctuations are on; on the Cosmic Microwave Background.

And then if we can measure by doing a galaxy survey of our local universe or the larger universe, we can see whether those correlate, if there are a lot of galaxies on one sort of scale and the surveys, does that correlate to these initial fluctuation? And it does. A Nobel prize was awarded for this.

This was a major discovery in recent astronomy or cosmology. And this gives us a very good idea of the distribution of matter within our universe.

Jacinta: [00:09:07] Yeah, exactly. That’s a challenging thing to explain, but I think you did great. I would just add that the thing that you want to pin down is the characteristic scale of the baryonic acoustic oscillations, and that essentially is like putting a ruler onto the universe at each time. So as the universe is aging, you’re trying to put a ruler against it at all of those times and see what the typical size of certain things is. So as you mentioned, you might do a galaxy survey and you might measure the typical distance between galaxy clusters, for example. But what HIRAX is going to do – it’s not going to look at galaxies. It’s more going to look at neutral hydrogen gas, which can exist between galaxies and therefore it could be a better tracer or a different tracer of this typical scale or typical size. And the reason why you want to do – why HIRAX is doing that – is actually to study dark energy because it’s this dark energy, which is accelerating the expansion of the universe.

And that of course was another Nobel prize to several people, including professor Brian Schmidt from our community in Australia. Shout out to Brian. So you’ve got dark matter, which is essentially adding gravity and pulling everything towards each other. But you’ve got dark energy, which is kind of like anti-gravity or negative gravity and pushes everything apart.

And this effect has changed in its strength over the history of the universe. So at the beginning, sort of after the Big Bang, it was relatively weak compared to the other forces, but now it seems to be dominating a lot more. So HIRAX is trying to look at the hydrogen, measure the typical length scales, and therefore make some conclusion about dark energy and maybe that lets us figure out what it is.

Dan: [00:11:00] So we basically get a different view of a different time in the universe. So the Cosmic Microwave Background is as early as we can look at 380,000 years after the Big Bang. And we can look at these scales and fluctuation. Now we can look at the galaxies now and see those scales.  But by looking at the neutral hydrogen with HIRAX, we can look at a time in between so we can look at the early universe beyond the CMB before galaxies formed, before a lot of the galaxies formed, and as you said, then we can get an idea of what the strength of dark energy was in those times and how the matter was distributed.

Jacinta: [00:11:42] Exactly. But that’s not the only thing HIRAX can do. It’s also looking at transients. Dan, do you remember what a transient is from the last episode with Patrick?

Dan: [00:11:53] I do. Okay. A transient is basically something which is out of varying with time in terms of its brightness, or another sort of factor. Or it’s something which goes – something which happens very briefly, once-off, and doesn’t occur again.

Jacinta: [00:12:11] Yeah. And in the previous episode 23 – talking to Patrick – we were talking about one type of transient object, which can be an X-Ray binary, where you’ve got black holes or whatever, sucking stuff off their partner stars. But in this case, HIRAX is looking for fast radio bursts or FRBs for short, and we don’t really know what this is at all, but it happens on millisecond scales.

So there’s just a sudden millisecond flash of bright radio light, and HIRAX is going to try and figure out what they are. And it’s an ideal telescope to do this because it’s going to see a wide area of the sky all at the same time. So if these things are quite rare and quite brief, you need to be looking kind of everywhere at the same time in order to spot them to have a good chance of spotting them.

But because they’re quite small, you also have to have good angular resolution as you need to be able to see things on small size scales. But we’ve already mentioned that HIRAX is going to have short baselines, and so it’s actually going to be better at looking at large scales, but they’ve come up with a way to solve that, which is the VLBI – very long baseline interferometry – which we spoke a lot about in episode,… what was it, back in season one, episode five with the EHT imaging of the black hole? Do you remember Dan?

Dan: [00:13:30] I may not remember which episode it was. I do remember discussing it.

Jacinta: [00:13:34] We were talking to Roger Dean and we went into a lot of details. If you want to know more about VLBI, you can go back to that episode, but basically you put a few telescopes out really, really far away. So long, large base lines away from your central core of telescopes. And these can be called outrigger stations. And that gives you the ability to see these shorter spacings on the sky. And so you’ve got a better chance of picking up these FRBs and to localize them, which means to figure out exactly where they’re coming from because some telescopes can see them, but say, okay, it’s coming from somewhere in this area, and with HIRAX, you want to be able to pinpoint exactly where in that area it’s coming from, and that’s going to give you a better chance of figuring out what’s causing it.

Dan: [00:14:21] Yeah. So we’ve given a good overview, I think of what HIRAX is going to be doing. We should probably hear from Kavi himself, who is the PI of this project, and he will be talking to you, Jacinta, about what it’s gonna do.

Jacinta: [00:14:35] All right, let’s hear from Kavi.

…music playing…

With us now is Professor Kavi Moodley from the University of KwaZulu Natal, welcome Kavi.

Kavi: [00:14:48] Thanks Jacinta.

Jacinta: [00:14:49] Kavi, tell us who you are, where you’re from, what you do.

Kavi: [00:14:52] Yeah. So I’m a professor at the University of KwaZulu Natal, as you mentioned to the listeners. My name is Kavilan Moodley. I’m interested in cosmology and astrophysics. So, I do research in this topic here in Durban.

Jacinta: [00:15:07] Okay. So tell us about the research group at the, at UKZN.

Kavi: [00:15:10] Yeah. So we’ve been – the research group at UKZN has been growing over the last few years. We now actually have set up an astrophysics research center at the university and we have a number of undergraduate students, postgraduate students and postdocs.

And our faculty numbers are growing. So the research there has two themes. One is more theoretical, looking at studying physical processes, gravity, etc. with application to astrophysics. And the second is more observationally; observational based. And that involves taking data from a number of telescopes and also building telescopes as we all talk about. And that’s focused more on extragalactic astronomy and cosmology.

Jacinta: [00:15:57] So we’re here in Durban at the moment for the SARAO Bursary Conference 2019 – we’re in Durban. And this is where UKZN is, is that correct?

Kavi: [00:16:06] Yes, that’s right. So UKZN, has two campuses, well, actually three campuses in Durban.

There’s a medical school, the Howard college campus, which has mostly engineering and the arts and social sciences. And then there’s the Westville campus where most of the science and management science are, and there’s another campus in Pietermaritzburg. And the education campus in Pinetown.

Jacinta: [00:16:28] So I came up early for the conference for the weekend just to check out Durban a little bit.

I just ended up kind of staying by the beach cause there’s a nice beach. The water is a lot warmer than in Cape Town and it’s kind of very tropical, lots of green all the way down to the beach. Tell us a bit more about Durban for our international listeners.

Kavi: [00:16:45] Yeah. Durban is fantastic. The weather is great all year round. There have been many reviews that have awarded it in one of the best destinations, including CNN and, you know, other websites though. Yeah, the water is warm so you can swim all year round. It’s a great location for getting access to the wildlife parks when you’re two hours away or the mountains; the Drakensberg is also two hours away. So, and Durban itself is interesting. It’s quite multicultural. People from many parts of the world are here. And you know, green rolling hills and, the food is interesting; very diverse.

Jacinta: [00:17:22] Yeah. I was just about to say the food. There’s the famous Durban curry and bunny chow.

Kavi: [00:17:27] Yeah, and that’s, I guess, part of my legacy being of Indian origin. So it’s quite exciting, but there’s quite an interesting multicultural mix in Durban.

Jacinta: [00:17:38] And, what exactly is bunny chow? I’ve been meaning to ask someone local from Durban.

Kavi: [00:17:43] It’s a, basically a hollowed out, a fraction or quarter or half of a loaf of bread, where the bread is not sliced and then it’s followed with the spicy curry.

Jacinta: [00:17:54] All right. Back to science. What research do you do in particular?

Kavi: [00:17:58] So my primary research interest is in cosmology. I’ve worked on the Cosmic Microwave Background or still work on in that area. And more recently I’ve moved into working on cosmology from using radio observations, generally trying to understand what the universe is made of – these mysterious components of dark matter and dark energy and just how galaxies form and evolve.

Jacinta: [00:18:24] What is the difference between astronomy and cosmology?

Kavi: [00:18:27] I guess maybe just terminology. Astronomy is interested in probably a wider variety of phenomena in the universe, and one would say it incorporates cosmology because cosmology is the study of the universe on the largest scales, including the large scale structure that we see; the Cosmic Microwave Background and a variety of other probes. Astronomy extends to studying stars, planets, galaxies. So one could say that astronomy covers scales that are much smaller than we study in cosmology.

Jacinta: [00:19:03] Right. And so as part of studying this cosmology, is it correct to say that you are helping in the development of something called the HIRAX telescope?

Kavi: [00:19:12] Yes. As I alluded to earlier, HIRAX is a project we are driving here out of UKZN and has a number of partners in South Africa and international partners. The goal is to build a radio interferometer array so that’s a collection of roughly a thousand dishes that are six meters in diameter. And unlike MeerKAT or other radio interferometers, the HIRAX will be a very compact array rather than the dishes being spread out.

And the idea there is that you have a lot of sensitivity to large scales, you know, which you need to map out the large scale structure in cosmology.

Jacinta: [00:19:51] First of all, tell us about the name HIRAX.

Kavi: [00:19:54] So the name HIRAX – it’s an acronym for the Hydrogen Intensity mapping and Real-time Analysis eXperiment.

It was cleverly devised because it’s the Latin name is Hyrax, spelled with a Y, not an I, refers to the rock dassie, which is a resident of the crew, like the MeerKAT is. And so HIRAX will be located in the Karoo site.

Jacinta: [00:20:20] So Hyrax is a little animal.

Kavi: [00:20:22] Yes. Actually a related, its closest relative is the elephant.

Jacinta: [00:20:26] Oh really? But it’s a tiny little animal, isn’t it?

Kavi: [00:20:29] One would think that it has relatives, which are more furry.

Jacinta: [00:20:32] So you’ve said that this is a thousand dishes in the Karoo near the SKA site?

Kavi: [00:20:37] Yes. It’s about 15 to 20 kilometers and currently we have actually funding up to 256 dishes, but we’re planning to expand to a thousand dishes.

Jacinta: [00:20:48] How is it different to the SKA?

Kavi: [00:20:51] The SKA has different scientific applications. Since we’re interested in cosmology in particular, we are trying to map out the hydrogen in the universe, but not on scales of the galaxy, but on much larger scales. We’re looking for a signal that’s a on scale a hundred times larger than the typical separation between galaxies. So to get sensitivity to very large scales, we need to have a very compact array. Conversely, if you want to discover things on very small scales, you have very long baselines. So you put your dishes far apart. And that’s what the SKA and MeerKAT are aiming to do.

Jacinta: [00:21:34] Right, so MeerKAT and the SKA are going to excel in sort of high resolution stuff, where you’re looking at smaller scales, smaller objects, whereas HIRAX is just to see huge large scale stuff. Is that correct?

Kavi: [00:21:47] Yes. That’s right, the volume that HIRAX will map out in the universe will be significantly more than many of the surveys that are will be undertaken by MeerKAT or the SKA.

Jacinta: [00:21:58] All right, and what are the main science goals of HIRAX?

Kavi: [00:22:01] There are two leading science goals. The primary one is, of course, dark energy, and the idea is to use the distribution of hydrogen in the universe on the very largest scales to map out a feature called the baryon acoustic peak. And that’s a characteristic scale.

As I mentioned, it’s quite large compared to the size of galaxies; 150 megaparsec so over around about 450 million light years. To do that, we need to map out a large volume in the universe. Once we measure the baryon acoustic feature, that gives us a unique lens scale, which we can then track over time because we measure the hydrogen at different frequencies and with that lens scale, we can then set a constraint on dark energy.

Jacinta: [00:22:51] So this is essentially a big telescope to study dark energy.

Kavi: [00:22:55] Yes, that’s right. Yeah. That’s its primary goal because we have a compact array, another important application of the telescope will be to discover transient phenomena and in particular fast radio bursts, which are a very hot topic at the moment, and pulsars,

Jacinta: [00:23:11] Okay, so what’s a transient and what’s a fast radio burst.

Kavi: [00:23:14] So a transient is an object in the universe that appears for a very short time. Fast radio bursts, for example, are very bright flashes in the radio sky – as bright as some of the other objects in the radio sky, and they only last for a very short duration, maybe a millisecond. Until recently, we’ve only had a handful of detections of these fast radio bursts, mainly because you need to cover a large area of sky and you need a broadband to detect these objects. Recently, a telescope like CHIME have changed that and are we now detecting hundreds of fast radio bursts. So HIRAX will be well positioned to detect lots of fast radio bursts in the Southern sky because it has a large collecting area and it has a large area.it surveys on the sky.

Jacinta: [00:24:05] And there any theories as to what could possibly be causing fast radio bursts?

Kavi: [00:24:11] Yes, there’s many theories out there. In fact, at one point there were more theories than they were actual detections of fast radio bursts. It’s pointing to some energetic event in the universe.

Probably the collision of, or the merger of, two massive stars is one theory. There’s a vast number of models out there, and collecting more data will help us to narrow down the range of models that we see.

Jacinta: [00:24:38] So HIRAX will hopefully help us figure out what is causing these things, right?

Kavi: [00:24:42] Yeah. And I think a key advance that we will make with HIRAX, which are the projects are also attempting, is, to try to localize these objects. Currently, it’s difficult to simultaneously survey a large area on the sky, and then have good angular resolution to pinpoint where they’re coming from. So typically, the localization of these FRBs, in the region where they’re detected, could be hundreds of galaxies.

So what HIRAX is hoping or is planning to do, is to have very long baselines, which would give us higher resolution. So we plan to build a small outrigger stations of about eight dishes. And place these working together with partners in other African countries at remote sites in these partner countries, and then do long baseline interferometry with these signals that will allow us to detect these FRBs.  And simultaneously localize them to within the galaxy, not just in a particular galaxy, but within a spiral arm in the galaxy.

Jacinta: [00:25:50] Okay, so you have HIRAX, which is a lot of dishes close together so that you can see large scale things, but also you want some telescopes associated with HIRAX, much, much further away from this compact central region so that you can do very long baseline interferometry, as you’ve said. And so therefore, if we can also see smaller details, therefore you can localize – so find out where the burst is coming from. So, which of these partner countries throughout Africa will potentially have some of these outrigger stations of telescopes?

Kavi: [00:26:21] We’re in discussion with a number of interested partners. Currently the most advanced partners are Rwanda and Botswana. We’re also in discussion where people from Namibia, Mauritius and potentially Mozambique and Kenya – but those are less advanced. So, in addition to the African partner companies, we have a HIRAX prototype at the Hartbeestboek Radio Observatory just outside of Johannesburg – that’ll also serve as another outrigger station. So we plan to start off with two or three outrigger stations before we expand to other partner countries. These stations are relatively easy to deploy because they just comprise eight dishes.

Jacinta: [00:27:06] So this has the potential to be quite a pan-African telescope.

Kavi: [00:27:10] Yes. And we’re hoping that we can contribute just a little in growing the interest in astronomy around the continent and in particular radio astronomy. These arrays are fairly easy to get up and running, and they would, they make excellent instruments for students and researchers to get their hands dirty.

Jacinta: [00:27:31] Yeah, exactly. There’s nothing like actually being at the telescope for the dish to boost your interest and your learning. Now, I wanted to get back to dark energy because we very briefly skipped over that, but it’s so interesting. Okay. Let’s just go through what is dark energy and why don’t we know what it is yet?

Kavi: [00:27:47] So dark energy is this mysterious form of energy, a component in the universe, which causes the universe to actually accelerate in its expansion. So if we had the regular matter, like the stuff that we’re made of and that we see around us, we would expect the universe to stop or slow down in its expansion, because the matter is putting it back.

However, a dark energy has a negative pressure and that’s almost like a repulsive gravity, and therefore causes the universe not to slow down in its expansion, but actually just speed up. So you may say negative pressure. That’s weird. And it is weird. It’s a strange stuff that we’re talking about.

The closest thing, and probably the best theory for dark energy at the moment is something called the cosmological constant, which Einstein proposed. Giving it a name doesn’t mean we know what it is. People think that it’s some form of the energy of the vacuum. So in the absence of all matter, this would be the only energy present.

But the theoretical predictions for this vacuum energy differ vastly by many orders of magnitude from what we observe for the value of the energy today.

Jacinta: [00:29:03] How is HIRAX going to help us figure out what it is?

Kavi: [00:29:06] So HIRAX will, as I mentioned, measure the large scale distribution of hydrogen in the universe that hydrogen chases the large scale structure.

And that structure has imprinted in it, something called the baryon acoustic peak, which is a unique lens scale that we can predict very accurately. So we will measure this lens scale with a percent level measurements and we will not just do that at one instant in time, but we will do that over a wide range of time.

So HIRAX will observe from about 11 billion years ago. To about 7 billion years ago. And that’s an important epoch because that is when dark energy was becoming important in the universe and was beginning – or starting after that period is, when it became dominant in the universe. So we will be able to measure how the universe – this lens scale – changes over time, over a wide range of time. And that will tell us what the behavior or properties are of dark energy.

Jacinta: [00:30:09] Okay, so it’s at least going to help us to understand more about the properties of dark energy and maybe that will lead us towards what it actually is.

Kavi: [00:30:19] Yes in particular, I mentioned the cosmological constant, that has a fixed equation of state, which is the ratio of the pressure to the density and its value is minus one, so it has negative pressure.

What we are hoping to do is to determine if they are deviations from that equation of state. So if the ratio is not minus one, that would point to very interesting new physics.

Jacinta: [00:30:44] Oh, lots of mysteries that HIRAX will help us solve. And when can we expect this telescope to be ready?

Kavi: [00:30:49] So at the moment, we are putting out a tender or bid for dishes for the telescope.

So that’ll be early next year. And we hope to by the end of having testing these dishes to install them at the Karoo site in South Africa.

Jacinta: [00:31:07] Great. And do you have any final messages for listeners?

Kavi: [00:31:11] Yeah. I’d like to direct the message to the young people out there who are fascinated by science and astronomy.

Certainly pursue your passion and it’s a hard journey, but don’t give up and you’ll be rewarded for it.

Jacinta: [00:31:25] Wonderful. And if people want to find out more about you and your research group and HIRAX, where can they go?

Kavi: [00:31:31] And you can look up the astrophysics and cosmology research unit.

ACRU , which is at UKZN, and we have a website. HIRAX also has a website which is hosted at UKZN. so it’s H-I -R-A-X-dot-U-K-Z-N-dot-ac-dot-za.

Jacinta: [00:31:47] And can we find you anywhere on social media?

Kavi: [00:31:49] We have an active social media presence through our research unit. So certainly if you look for ACRU on Twitter, Facebook, you could catch up with me indirectly through those social media platforms.

Jacinta: [00:32:04] Thank you so much for speaking with us today, Kavi, it’s great, to catch up with you as always.

Kavi: [00:32:08] Thanks very much Jacinta, and I hope you have a good day.

… music playing…

Jacinta: [00:32:20] So a lot of great science there. I do also have to admit, Dan, that I didn’t taste bunny chow in Durban because I can’t really handle a lot of spice.

Dan: [00:32:30] Well, you missed out.  I don’t know if the listeners know: I grew up in KZN. So I grew up on bunny chow – it’s delicious. I mean, it’s very high on the carbs because you’re having a lamb and potato stew inside half a loaf of bread. Yeah.

Jacinta: [00:32:51] You wouldn’t want to go back to work after that. You’d be very, very drowsy. Food coma.

Dan: [00:32:58] Yeah. You know, delicious. I could do one right now. I’m sure

Jacinta: [00:33:02] I tried one in Cape Town once, but I think it was like a really watered down Cape Town version ‘cause it wasn’t very spicy.

I want to know what dark energy is. Getting back to science again.

Dan: [00:33:15] I don’t we all, and I think that that’s one of the nice things. This is another great project, which is getting both in South Africa, and maybe we’ll answer some of those questions or at least get closer to answering those sorts of questions.

It’s great. We hear a lot about MeeerKAT. We hear about SALT and some of the other big projects that are going on, but there’s a lot of these other projects happening too. We’re exploring a lot of different realms of science all at the same time and it’s exciting.

Jacinta: [00:33:45] Yeah, definitely lots of different things.

It was a bit refreshing to talk about radio astronomy, that’s not MeerKAT, even though I love it. There are other instruments out there. Well, all of that talk about bunny chow. I kind of want to go and get some lunch now.

Dan: [00:34:00] Yeah, me too. All right. Thanks for joining us again, and we hope you’ll join us on the next episode of The Cosmic Savannah

Jacinta: [00:34:07] In the meantime, you can visit our website, thecosmicsavannah.com where we’ll have the transcript of this episode and related links. You can also follow us on Twitter, Facebook, and Instagram @cosmicsavannah, that Savannah spelt, S-A-V-A-N-N-A-H. Thanks to Sumari Hattingh, Brandon Engelbrecht, Lynette Delhaize, and Thabisa Fikelepi for social media and transcription assistance.

Also to Mark Allnut from music production, Janus Brink for the Astrophotography and Lana Ceraj for graphic design. 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 and we’ll speak to you next time on the Cosmic Savannah.

…music playing…

Dan: [00:35:13] All right. Thanks for joining us again, and we hope you’ll join us. Argh!

This is why we have a script

Jacinta: [00:35:25] so that you can not read it!

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

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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.