Episode 56: Our supermassive black hole

Auto-scrolling transcript. See below for static transcript.

with Dr Iniyan Natarajan

The Event Horizon Telescope (EHT) Collaboration has unveiled the first image of the supermassive black hole at the centre of our own Milky Way galaxy! This is the first direct evidence of the black hole in our galaxy. The image was produced by a global research team called the EHT Collaboration, using observations from a worldwide network of radio telescopes.

We are joined by Dr Iniyan Natarajan who is a postdoctoral fellow at the University of Witwatersrand and who was part of the team of over 300 astronomers who made this possible.

This is the first image of Sagittarius A* (or Sgr A* for short), the supermassive black hole at the centre of our galaxy. It’s the first direct visual evidence of the presence of this black hole. Credit: EHT Collaboration
A view of the M87 supermassive black hole in polarised light: The lines mark the orientation of polarisation, which is related to the magnetic field around the shadow of the black hole. Credit: EHT Collaboration

This week’s guest

Episode Links

EHT Press Release: https://eventhorizontelescope.org/blog/astronomers-reveal-first-image-black-hole-heart-our-galaxy
African Millimetre Telescope: https://www.ru.nl/astrophysics/radboud-radio-lab/projects/africa-millimetre-telescope-amt/

Dan’s TEDx talk!


By Justine Crook-Mansour and Moloko Makwetja.

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

[00:00:08] Jacinta: 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.

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

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

[00:00:31] Dan: Welcome to episode 56, where we have some exciting news.

[00:00:35] Jacinta: Hi everyone. Yeah. Sorry. This episode’s been slightly delayed by COVID, as many things are these days, so I’m sure you’ll forgive us. But yeah, sorry about that. But in the meantime, of course, there has been some extremely exciting news, which I’m sure many of you have already heard about. Of course, the Event Horizon Telescope put out a new press release.

So you may remember in 2019, the EHT telescope took its first picture of a supermassive black hole. That was M87*. And that’s a supermassive black hole at a galaxy sort of outside of our own galaxy – a different galaxy. And then when Dan and I heard that there was going to be another announcement from the EHT, Dan was like, “Oh, it might be Sagittarius A*. SagA*!”

[00:01:26] Dan: So, yeah. We are joined by Dr Iniyan Natarajan, who is a postdoctoral fellow at the University of Witwatersrand in Johannesburg. And he’ll be telling us a little bit about the discovery and his involvement and some exciting news in terms of Africa’s involvement going forward.

But first up, I think we should just chat a little bit about the discovery, not taking too much away from Iniyan. Super cool. I mean the second black hole we’ve imaged. First one M87*, as you’ve mentioned. And now we’ve got a nice selfie, I guess, of our own black hole.

[00:02:01] Jacinta: Yes, just so cool. Like, ah, it’s so exciting! For years, we’ve been telling people… yeah, no, there is really a supermassive black hole at the centre of the Milky Way. We know it’s there. We’ve seen indirect evidence of this by other stars kind of orbiting around nothingness – something that looks blank. And, you know, studying those orbits, we know that it has to be of a certain mass and the fact that we don’t see it means it has to be a supermassive black hole, based on the mass. But it’s very, very, very hard to make an actual image of it. Iniyan will go into detail about why that is. But yeah, I guess examples online have said it’s kind of like taking a picture of a toddler that keeps moving really, really fast. It’s very difficult.

[00:02:47] Dan: I think it’s even… I think it’s even worse than that. It was something like… we should look this up. It was something like, you know, taking a photo of a penny in New York from London or something. It’s insanely high resolution. And they do this in very incredible ways using interferometry, using telescopes on either side of the world. And Iniyan will be able to explain that too. We keep referring to M87* and Sagittarius A*, but it’s actually a black hole. Jacinta, do you care to explain why we keep doing that?

[00:03:21] Jacinta: I mean, it’s just the nomenclature. It’s just the symbols that we use in astronomy to represent these things. So pretty much all galaxies have supermassive black holes at their centre. We don’t really know why yet. And that supermassive black hole, it has the name of the galaxy. And then it has a little asterisk next to it. When we say it out loud, we say “star”. So the supermassive black hole at the centre of the galaxy M87 is M87*. So then within the Milky Way it’s slightly different naming. Dan, do you want to explain that part?

[00:03:53] Dan: Yeah. So it’s called Sagittarius because it’s in the constellation Sagittarius. And then the ‘A’ actually refers to the region it’s in. So you would have seen the MeerKAT image some years ago of the area around our black hole in the radio, which was a very cool image from MeerKAT. And that area is called Sagittarius A. It’s kind of this complex radio source. There’s all sorts of stuff going on. When it was discovered, it was obviously, you know, in the Sagittarius constellation, and it became known as Sagittarius A. And then you add the star, the asterisk, which refers to the black hole within that region.

[00:04:31] Jacinta: Yep. Exactly. And then we’re lazy. So instead of saying Sagittarius A*, we say Sgr A*.

[00:04:36] Dan: We’re trying to save time.

[00:04:41] Jacinta: Yep. Save time. More astrophysics.

[00:04:46] Dan: Save characters on Twitter.

[00:04:47] Jacinta: Yeah, yeah. Yeah. It’s probably due to Twitter actually.

All right. Shall we let Iniyan explain the rest?

[00:04:56] Dan: Absolutely.

[00:04:57] Jacinta: All right. Let’s hear from Iniyan.

[00:05:01] Dan: Today we’re joined by Dr Iniyan Natarajan. And he is a postdoctoral fellow at the University of Witwatersrand in Johannesburg, South Africa. Iniyan, welcome to The Cosmic Savannah.

[00:05:15] Iniyan: Thanks Daniel and Jacinta. Yeah. I’ve listened to quite a few episodes of the podcast and yeah, I’m happy to be on the show.

[00:05:22] Jacinta: Thank you very much for joining us Iniyan. We’re very excited to have you today to talk about some very exciting new work. But before we get into all of that, can you just quickly tell us who you are and where you’re from and what you do?

[00:05:35] Iniyan: Yeah, so I am originally from India. I did my undergraduate education in computer science and engineering. And I moved to Cape Town to do my Master’s in astronomy at the University of Cape Town. And then I continued on with a PhD at UCT, which focused on radio astronomy and techniques for analysing radio interferometric data. So I’m generally working more on the technical programming side of things. Algorithm development and that kind of stuff. And then I did a postdoc at Rhodes University, and now I’m a postdoc at Wits University. And I also work closely with the radio astronomy research group at SARAO.

[00:06:17] Dan: Excellent. So as Jacinta mentioned, there’s some very exciting news, which came out just last week, where the Event Horizon Telescope revealed the image of another black hole. The second from the Event Horizon Telescope. And this time, our very own black hole at the centre of our Milky Way galaxy, which is called Sagittarius A*.

Could you tell us a little bit about that and why it’s so exciting?

[00:06:39] Iniyan: Yeah. So the collaboration recently released the first black hole images of the supermassive black hole at the centre of our own galaxy. And this data was collected in 2017, along with the other black hole image that was released two years ago.

And the black hole at the centre of our galaxy is something that we are looking at like straight through the galaxy. And that makes it more difficult to image. And also it’s a much smaller black hole than the other one that was imaged in 2019. Which also means it’s rotating faster, which means you need to develop new algorithms and new software to actually be able to handle that. Which is why it took almost five years since the collection of the data to come out with this image in 2022. And it’s exciting because it’s our own black hole at the centre of the galaxy that we live in.

[00:07:31] Jacinta: So exciting. I’m just like bursting at the seams over this. Dan and I were both messaging during the press release being like, “Is this humanity’s final moments of not knowing what our local supermassive black hole looks like?”

But Iniyan let’s take it back a step for our listeners. What exactly is a black hole and what is special about a supermassive black hole?

[00:07:56] Iniyan: Yeah. So a black hole is the point in spacetime where even light cannot escape. The escape velocity that’s needed to escape the gravitational pull of the black hole is so high that not even light or anything traveling at the speed of light can get out of the influence of black hole. And this point of no return is called the event horizon, which is why the telescope is named Event Horizon Telescope. And these are some of the most, some of the weirdest, like strangest and most high-energy phenomenon in the universe.

And there are different types of black holes. Or black holes can form in different ways. The one that people probably more commonly hear of is the stellar-mass black hole, where a star that’s more than about 30 times the mass of the Sun… when it dies, it invariably turns into a black hole, which is much smaller than what we call supermassive black holes, which are giant black holes that are found at the centres of galaxies. And at this point we believe that every galaxy hosts a supermassive black hole at its centre.

[00:09:00] Dan: So how big is our supermassive black hole? You said it’s a lot smaller than the one in M87, but how small is small and how big is big?

[00:09:08] Iniyan: Oh yeah, the black hole at the centre of M87 is really a giant black hole. Like it’s mass is like 6.5 billion times that of the Sun. In comparison, the massive…

[00:09:19] Jacinta: 6.5 billion?

[00:09:23] Iniyan: Yes, it’s crazy. It’s really one of the largest black holes out there. And I think that the limit for like what you can call a supermassive black hole is 10 billion times the mass of the Sun. There is a class that’s proposed, kind of like ultra-massive black holes. Because I think we are really running short of superlatives here. But yeah, so the M87 black hole is something that’s really large. In comparison, the black hole at the centre of our galaxy is more common and it’s only about 4 million times the mass of the Sun, only.

[00:09:59] Jacinta: Cheeky 4 million.

[00:10:01] Dan: So you mentioned that, you know, to create an image of our black hole, the Sagitarius A* at the centre of the Milky Way, was somewhat harder than creating the image of M87. You know, the data was taken at the same time and it took two years to get the image of M87. And M87 is a lot further away from us. It’s in another galaxy. Is that because of the size?

[00:10:27] Iniyan: No. In fact, Sgr A* appears slightly larger in our sky than M87*, but the difference is that M87 is a different galaxy. And you’re kind of looking at a different galaxy away from our galactic plane, where most of the stars and the gas and the dust in our galaxy is located. You’re not looking through all this interstellar gas and dust when you try to image the M87 black hole. That’s one of the reasons.

And the other reason was that the black hole in M87 is a much larger black hole. It’s far bigger than the entire Solar System. In comparison, the Sgr A* is probably about the size of Mercury from the Sun. So it’s far bigger, but it’s much further away. So it appears slightly smaller in the sky than the Sagittarius black hole. But because it’s far bigger, it also rotates slowly. During the entire duration of the observation, the black hole doesn’t change in appearance much. In contrast, Sgr*, being a smaller black hole, rotates at a much faster rate. In fact, while this rotation rate is expected to be on the order of days to a month for M87, for Sgr* it’s on the order of minutes. So the appearance of Sgr* also changes as well. It’s what we call variability.

So that, and the fact that we had to look through all the gas and dust in our own galaxy made it harder to analyse this data. And that’s why we had to come up with like new methods of calibrating, imaging, and modelling the data, and extracting science from that.

[00:12:06] Jacinta: All right. So it’s really hard is the moral of the story.

[00:12:10] Dan: So how do we observe these? So you mentioned that not even light can escape from a black hole. We’re looking at the event horizon of the black hole. What are we looking at and how do we photograph it?

[00:12:21] Iniyan: So what we see is a bright ring and a central depression in brightness, basically like a darker region within the ring. And this comes about because the central part, which is also called the shadow, is basically our line of sight into the black hole. Basically that’s where there’s no light. No light escapes from that part.

But we are lucky in that these supermassive black holes are generally surrounded by hot gas and like swirling plasma that’s going on around it, that it’s kind of accreting due to this gravitational pull from its environment. And this gas can radiate. And this light, when it approaches a black hole at a certain angle, will just fall into the event horizon and be lost to us forever. But at certain angles, this light, instead of falling into the black hole, can go around the black hole and come towards us. And this kind of happens to light that approaches the black hole from all directions. And this light gets warped around the black hole, due to the spacetime warping. Which is why, all around the black hole, you see this ring of fire.

[00:13:29] Jacinta: And how come there’s clumps in the picture? Like we’ve all seen the picture now of M87* and a Sagittarius A*. And they look fairly similar, but not quite the same. But both of them had these kinds of clumps of bright patches. What are they?

[00:13:44] Iniyan: Oh, yes. This is something that people probably do not expect to see because of what they saw in Interstellar. For example, there it appears more like Saturn.

[00:13:52] Jacinta: Yeah, that’s exactly what I was thinking of.

[00:13:55] Iniyan: So in the movie, the black hole appears more like Saturn and the rings are like very clearly outlined and there are no clumps, or there are no brighter and like darker regions relatively on the ring. This is due to the Doppler effect, basically, which is something that we studied in like high school physics. But basically the light coming towards us will appear brighter than the light going away from us. And then that’s basically what causes these changes and how we perceive the ring to be.

For example, there’s more variability in the Sgr A* image than what we saw from M87. So you’ll probably see clumps, or what you can call hotspots, in different regions of the ring in both M87 and Sgr A*. And in Sgr A*, because it’s rotating at a much faster rate, so during the entire duration of the observation, the black hole’s appearance keeps changing. So basically, of the thousands, tens of thousands of images that were made, basically all these images were algorithmically classified into different clusters based on how the ring morphology shows up. And that’s why you see these clumps of matter. Maybe it’s slightly different areas on the ring, but more than 95% of the images show the ring-like structure. And the one big image that we all saw is an average of all those images.

[00:15:18] Dan: Okay. So you were averaging images from different telescopes and that’s what the Event Horizon Telescope is? Could you just explain to us how the Event Horizon Telescope works and how it gets these images?

[00:15:30] Iniyan: Yeah. So the Event Horizon Telescope is a global network of telescopes that operates telescopes or observatories that are located far and wide around the world to generate the equivalent of a telescope that’s the size of the Earth. And this is done by a technique called interferometry, which ultimately, again, is something that we all studied in high school physics. It uses the principle of interference of waves in a clever way to combine signals from telescopes that are located at different locations on Earth. When the signals are combined in a certain mathematical way, it is as if we are collecting these signals from an Earth-size telescope. But with a lot of holes in the telescope. And that’s what makes radio astronomy and imaging in radio astronomy much harder.

[00:16:23] Dan: So we want to fill those holes, right?

[00:16:25] Iniyan: Yeah. This technique is called a very long baseline interferometry. And basically the baseline is the distance between these different telescopes or observatories that constitute the RA. And as these baselines become longer and longer… again, you know how astronomers are with these superlatives… we just call them very long baseline interferometry.

[00:16:43] Jacinta: Okay. So we have essentially a telescope that’s the size of the Earth, as you say. But thankfully holes in it so that it doesn’t completely block the Sun. And it’s made this amazing image of the supermassive black hole at the centre of our galaxy. We see rings. We see these clumps. And this is, of course, work that’s been done by an enormous collaboration of many, many different astronomers around the world. And you’re part of that collaboration, is that correct? And what was your involvement in this project? What was your part in this?

[00:17:14] Iniyan: So the collaboration consists of 350 scientists located around the world on five different continents. So my involvement in this was, as someone who has worked on algorithm development for imaging, calibration, and simulation of astronomical data, my involvement has been in those areas. So one of the things that I’ve been involved in is to write a simulation software along with Roger Deane to basically simulate how a black hole would look to a telescope like the EST or to any very long baseline interferometer. And so basically this software has to take into account all the different atmospheric effects and all the characteristics of the instrument or the different dishes that constitute this array. And so basically you put all this information and also theoretical models of how you think this all should look like. And geometrical models that we can kind of create with like basic geometry. So basically this software takes in a lot of information about the target for observation and information about the Earth’s atmosphere and information about like how your telescope works and the characteristics of the telescope. And it spits out data and images of how a certain source that’s given by the theoretical simulation would look through a telescope like this. And this has been used to create a lot of simulations, like within the collaboration, for a lot of different studies, including this one. That’s one of the things.

And the other thing that I was involved in was to work on basically characterising a bunch of morphological properties of the different rings in all these like thousands of images that were created. So there are different imaging pipelines, or basically like different imaging software packages. Each of it has created thousands and thousands of images from this data. So, if you remember back when I said our telescope has a lot of holes, the measurements that could have been made from those regions, which are holes, could be anything. So basically there are an infinite number of possibilities that exist. But based on how we know, or based on the physics that we know… based on how we know black holes work, and based on other observations, like past observations and observations in other wavelengths, we can kind of put some constraints on what the measurements in these regions should be.

And so basically you end up with thousands of different realisations of these black hole images. None of which can claim superiority over the other. While like image number three is as equally plausible as image number, I don’t know, 5 065. Something like that.

So I worked on writing some software pipelines, which also involved a host of different software packages, which are all used to characterise the morphology of the ring and basically different parameters, like the diameter of the ring and the width of the ring and the location at which the hotspot is located on the ring. So basically, all these parameters we kind of extract from each of these images. And then we also classify these images based on how much they look like a ring or how much of a certain kind of ring they look like. So I was also involved in that kind of analysis and software development for this project.

[00:20:35] Dan: Awesome. And we should point out, I don’t think we mentioned that, you know, these are radio telescopes, the Event Horizon Telescope, but they work at a slightly different wavelengths to MeerKAT, which we talk about quite regularly. They work in the millimetre wavelength. Africa is hopefully going to be joining the Event Horizon Telescope in the coming years with the African Millimetre Telescope.

Can you tell us a little bit about that? Sounds very exciting.

[00:21:00] Iniyan: So yeah, we would really love to be part of the Event Horizon Telescope network. This would actually be mutually beneficial to the African astronomy community and also to the Event Horizon Telescope collaboration. For example, one of the primary targets of the EHT is Srg A*, which is located in the southern hemisphere. So, the EHT can do with all the telescopes, they can get in the Southern hemisphere. So having a telescope in Namibia or the African Millimetre Telescope, but greatly benefit the EHT. If you think of the different telescopes or stations involved in interferometry, as each shaking hands with each other, just the addition of one more telescope basically introduces a number of baselines and that increases the amount of data that we have from any observation.

And then that improves the physical constraints that we can put on, at the ultimate science that we can get from these. We also hope that at some point we can also have a station in South Africa, which could also provide a much needed short baselines. If you have a station in South Africa and have a station in Namibia, then it becomes easier to constrain the characteristics of the antennas; which are very important in how they behave during an observation.

These are called short baselines, as opposed to the baselines that you can form between a telescope in South Africa and a telescope in Chile, for example, and these help us constrain the properties of the instrument itself better. So this would be a massive boost to the SagA* campaign in the EHT, and also it will really work in synergy with our other projects like MeerKAT and other high-energy astrophysics projects or multiwavelength projects that are being pursued in South Africa.

[00:22:46] Jacinta: That’s so exciting, and this might be a novice question, but will the SKA be able to be part of the EHT eventually when it spilled or does it operate at a completely different frequency?

[00:22:58] Iniyan: Well, the SKA does operate at a much lower frequency or at a much higher wavelength, as we would say.

[00:23:05] Jacinta: Okay. So probably not part of the EHT itself, but probably we’ll be able to do some sort of VLBI with the SKA, but just not at these wavelengths.

[00:23:16] Iniyan: Yeah, exactly. They’ll transfer SKA-VLBI and, we can definitely observe the centre of our galaxy, but we will be observing at a much different wavelength. Which is also, always necessarily, it always gives us a complementary picture of what’s going on.

[00:23:31] Jacinta: I guess we won’t be able to see Sagittarius A*, though at those longer wavelengths, because there’s other stuff intervening our line of sight that will be glowing at these radio wavelengths, and so blocking our view of the centre.

[00:23:45] Iniyan: Yeah. So I just that itself would be invisible to us because it’d be opaque at those wavelengths.

[00:23:50] Jacinta: Right.

[00:23:50] Dan: What is next for the EHT? We’ve got our picture of M87, which is, I think the nearest galaxy we’ve got our picture of Sagittarius A*. I assume we’re working on improving those images, but if you’re able to tell us what’s next.

[00:24:05] Iniyan: This is kind of the very beginning of EHT imaging. On the instrumental side, there are efforts, for something called the next generation Event Horizon Telescope, which aims to add a lot of different stations to the existing EHT array, which will of course greatly improve our ability to image these black holes.

There are also like maybe, longer term plans for putting some radio telescopes in space, and doing interferometry with much larger baselines, but it comes with its own complications. It’s basically our stations are moving relative to the Earth. So this is more complicated than that; but as far as the observations and the science are concerned, the image that was released recently, it’s just the Stokes I image, what we call the total intensity image.

And there are still polarimetric studies to be done, and polarimetric images to be made with the Sgr A* data; and so, in a similar way to the images that were ever released in 2021 with M87. Also, EHT has collected data in 2018, and also again in 2021 and 2022 with a few new stations in the mix. So you also expect the analysis of the data to greatly improve on what we have now.

[00:25:19] Jacinta: I just want the listeners to understand that this is extraordinarily difficult stuff that’s going on. So it takes years to analyse the data and try to get an actual image and get some science results out of it. So that what you and the whole team union have done is really remarkable.

And so I think what you are saying is that, we’ve seen the images of Sagittarius A*, M87 star in total intensity, meaning just collecting all of the light that we can coming from there. But then we want to look at the polarization. Meaning light can be polarized in different directions and you can split up that light.

And you want to look at the black hole in light that’s polarized in one direction versus light that’s polarized in a different direction. What can we learn about an object, if we look at the polarized light? And you mentioned that we have seen polarized images from M87. I think I might’ve even missed that. What did that look like?

[00:26:09] Iniyan: Oh yes. So those results came out in 2021. I mean, obviously not in big press conference like this, but I think it was about a year ago that released the polarimetric measurements of M87. So basically, when you look at these images in polarized light, you get an idea of the characteristics of the magnetic field that exists in the region around the black hole.

So you can get the direction of polarization offline, we still see how the magnetic fields are organized, or how strong they are and how much they can affect, the accretion of matter around the black hole. And this is exactly what we try or what we hope to do with Sgr A* data, which we hope will help us improve our constraints on the accretion rate or like the strength of the magnetic field around the back hole and then like the structure of the magnetic fields around these black holes.

[00:27:01] Jacinta: Right. So this is going to help us to understand magnetic fields.

Answer that question about that one annoying people, always often a conference and you can see that the effect of magnetic fields.

[00:27:13] Iniyan: Yeah that is so true.

[00:27:14] Dan: I mean, the magnetic fields around a black hole must be nuts.

[00:27:18] Jacinta: Yeah, that must be doing crazy things. Thank you Iniyan, just one more question from me and then I don’t know if Dan has more questions, but I’ve just thought of a whole bunch.

What did it actually feel like, to you, when you first saw the picture that we saw in the press release recently, and how did it feel when it was released to the world after so much work?

[00:27:37] Iniyan: It was so different between M87 and Sgr A* during the M87 press release. I was actually with my family back in India.

So we were watching the press conference live. I was with mom and dad, and I was getting all excited and like trying to explain stuff to them and how successful I was, but at least the general excitement kind of like. Cut down to them. But, it was an incredible feeling, I was a much newer member in the collaboration when the M87 results came out.

So it was just like such an exciting feeling. And I just wanted to be more of a part of these things. I mean, you work hard, you work a lot, you work for a long time, like for years and years, and then suddenly you see something like this, like, you know, terabytes of data and like everything compressed into like, I don’t know, A hundred KB image.

But it’s worth it. It’s very worth it. And I have been able to become like a bigger part, at least I’ve been able to do more tasks within the Sgr A* project, and I’m hoping to be involved in these things, further in the future.

[00:28:45] Dan: Iniyan, thanks so much for sharing your excitement with us. And I think you did an excellent job of explaining to us. I’m sure you did to your parents.

[00:28:54] Iniyan: They were also so happy.

[00:28:58] Dan: Is there anything you’d like to share with our listeners, before we go?

[00:29:02] Iniyan: Yeah. I just want to thank you guys. It’s been a really great chat. And talking about these things with you two years, working from home, you do want to just chat with friends about stuff.

In a relaxed setting.

[00:29:17] Dan: But it’s been an absolute pleasure.

[00:29:18] Jacinta: So great. Thank you so much, Iniyan, and good luck with the rest of your work.

[00:29:22] Iniyan: Thanks you too. Thanks for inviting me.

[00:29:31] Jacinta: Oh, that was awesome. Just so exciting. We now know what our black hole looks like.

[00:29:38] Dan: Super cool. I think everyone was over the moon in 2019, we didn’t really know what a black hole or the area around the black hole was going to look. This is very similar, I guess, with some slight changes and obviously a much smaller and harder to image object as in the unexplained, but super cool to have our own galaxy, our own galaxies black hole.

Now we’ve got a little nasty postcard image of it. Yeah, I think that the other cool thing, which, you know, if you haven’t seen the M87 image, then you’re in the minority of the global population, because I think that the number was four and a half billion people saw that image, which has got to be the biggest, you know, astronomical event or news event ever!

[00:30:23] Jacinta: Yeah, it’s messy. It’s the eye of Sauron kind of looking at you. That’s kind of what it looks like. I’m just going to Google now M87 polarized image, because I want to know what let’s talking about. Polarized. Oh, wow. Oh, cool.

[00:30:43] Dan: It looks fake.

[00:30:44] Jacinta: Okay. It does look fake. Is this real?

[00:30:47] Dan: Oh no it is, yeah. Cool. So you can see that the magnetic fields all spiralling in, and there’s some weird stuff going on on the left there.

[00:30:55] Jacinta: Yeah. We’ll put it on the blog as well, but, Google it yourself and have a look. It’s like the glowing ring, like the eye of sauron thing, but then it’s got stripy things around it, like eye lashes kind of thing inside the eye. It’s cool. Really cool. So that tells us about the magnetic fields.

[00:31:14] Dan: I don’t know if as many people as that have seen Interstellar, probably not, but the image in Interstellar, which Iniyan referred to too was also cool.

And then there was a simulation, and at the time I think it was one of the better simulations, if not the best simulation of the area around a black hole, because movies have budgets that astronomers don’t so

so yeah, and I think that if you have a look at it Interstellar’s black hole, it’s actually a very, very realistic simulation too.

[00:31:46] Jacinta: Yeah. And the, the astrophysics on that movie is really quite accurate because a Nobel prize winner Kip Thorne consulted on that movie, except at the point from which they fall, into the black hole.

Sorry for that spoiler alert. But, should should’ve said that first spoiler alert, but, from then on it’s purely Hollywood physics because yeah. That things fall apart pretty quickly from there.

[00:32:12] Dan: I don’t know what the statute of limitations on movie spoilers is, but I feel like Interstellar has been around long enough that.

Okay, great. Very exciting stuff coming up. And I think that it’s awesome that, Africa’s going to be getting involved soon. The AMT is coming and that’ll add as any unsaid, various baselines. So it’ll add more than just one telescope. It adds a whole lot of baselines, which means we’re getting much more accurate images.

And the EHT telescope is not done. There’s going to be continuous improvements and I’m sure they’ve got some awesome new surprises for us coming up, which they’re not allowed to leak. There’s a huge amount of secrecy around the EHT. I don’t think it was for the first one, but I feel like, you know, everyone kind of knew this was going to be Sagittarius A*, but still, I guess it’s just for the media. They do a really good job of it.

[00:33:05] Jacinta: Yeah. Well, I think it’s great cause I didn’t know about it either. And neither did you, I think. And so it was a nice surprise.

[00:33:11] Dan: All right. I think that’s it for today.

[00:33:15] Jacinta: Yeah. I guess before we wrap up, we do our usual traditional. How are you Dan? Sounds slightly nasally, you’re alright?

[00:33:25] Dan: Yes. Yeah I have had something over cold, just in my nose and yeah, it’s probably a good thing we delayed for a week so that I sound even less nasally than did last week. Otherwise. I’m good. I think, I feel like it’s the end of the year already. I feel like I’ve burned up all my energy for the year, but we’re only in May, so. But otherwise I can’t complain too much. How are you?

[00:33:50] Jacinta: Yeah, I’m doing really well, got lots of exciting science going on, which I’ll be able to talk about eventually. But the big thing is that this weekend on Saturday, I’m giving a TED talk TEDx, in my home town, which is going to be really exciting.

Uh, Dan you’ve actually given a TEDx talk. So I think we should link to your talk, somewhere on our website. Cause it was really great. It was about kind of ethnoastronomy, cultural astronomy in South Africa. And well, after my talk, I’ll be able to explain a bit more about the topic of mine, but I’m really looking forward to it.

I’ve been practicing really hard, dress rehearsal is tomorrow, bought new boots for it, which I can’t wait to wear.

[00:34:32] Dan: I mean, I hope the camera takes in your boots and doesn’t just focus on the top off of you then; otherwise we can post a picture of the piece on the wayside to.

[00:34:42] Jacinta: Yeah, we should. And other than that, yeah, still at home in Australia, hanging out with my dog. You follow me on Instagram, you’ll see lots of pictures and videos of the dogs, and also the birds that live on our bushland property, lots of birds around.

[00:34:57] Dan: Yes. I see you’ve been taming magpies.

[00:34:59] Jacinta: Yes. Yeah. We have these magpies and all of these other different types of birds that come to get fed whenever we feed our dog outside and now I’m teaching them tricks. They jumped for their food. One of the magpies takes food out of my hand. So yeah, having,

[00:35:14] Dan: I’m sure you know you not supposed to feed the wildlife Jacinta…

[00:35:16] Jacinta: I mean, true, but we have lived here for about 20 years and T\they tamed us. They trained us, so well, we’ve learnt what we are not allowed to feed them. So I think the birds will be okay.

Alrighty. Yeah, I think, I think we can wrap it up there.

[00:35:38] Dan: Oh, good luck for your talk on Saturday, and I hope that we are able to watch it all soon. Judging by my TEDx talk. It took a couple of months for the TEDx to approve it and kind of edited down and everything. So hopefully we’ll be able to see that sooner rather than.

But yeah, I think we should wrap it up there. Thanks again for listening. We hope you’ll join us again next time on The Cosmic Savannah.

[00:36:01] Jacinta: You can visit our website, the thecosmicsavannah.com, where we’ll have the transcript links, pictures and other stuff related to today’s episode.

[00:36:08] Dan: You can follow us on social media, Twitter, Facebook, and Instagram @cosmicsavannah.

That’s savannah spelled S, A, V, A, N, N, A, H. You can also now find us on YouTube where audio only episodes are uploaded with closed captions, which can be auto translated into about 200 different languages, including Afrikaans, isiXhosa, and isiZulu.

[00:36:28] Jacinta: Special thanks today to Dr. Iniyan Natarajan, for speaking with us.

[00:36:31] Dan: Thanks to our social media manager, Sumari Hattingh, and our audio editor, Jacob Fine.

[00:36:36] Jacinta: Also to Mark Allnut for music production, Michal Lyzcek for photography, Carl Jones for astrophotography, Susie Caras for graphic design, and Justine Crook-Mansour, and Moloko Makwetja for transcription.

[00:36:48] Dan: We gratefully acknowledged support from the South African National Research Foundation, the South African Agency for Science and Technology Advancement, the South African Astronomical Observatory and the University of Cape Town Astronomy Department.

[00:36:59] Jacinta: And we’d really appreciate it if you could rate and review us and recommend us to a friend.

[00:37:03] Dan: And we’ll speak to you next time on The Cosmic Savannah.

[00:37:11] Jacinta: Episode 56 Dan and Jacinta commencing silence. I forgot your name there briefly!

I was like, is it Dan? Is it Dan? What’s happening to me today?

[00:37:26] Dan: I feel like we’ve really grown apart since you left the country

[00:37:31] Jacinta: No! It’s not true.

All right. Serious face. Let’s go.

[00:37:40] Dan: Okay