Imagery Of M87's Black Hole Shows Polarity Flip - ESO Explains - video Dailymotion

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Using Event Horizon Telescope observations of M87's black hole from 2017, 2018 and 2021, "astronomers have found some changes in this now iconic image that could be caused by variations in the magnetic field around the black hole," according to the European Southern Observatory (ESO).   Credit: ESO  Directed by: Luis Calçada Hosted by: Suzanna Randall, Violette Impellizzeri  Written by: Suzanna Randall Editing: Martin Kornmesser Videography: Angelos Tsaousis    Footage and photos: ESO, EHT Collaboration, M. Kornmesser, L. Calçada, N. Risinger, P. Horálek, spaceengine.org, DSS2, ESA/Hubble, RadioAstron, De Gasperin et al., Kim et al., Jean-Pierre Luminet, Weih/Fromm/Younsi/Rezzolla, Smithsonian Astrophysical Observatory Music: Martin Stuertzer, Envato Animations & Infographics:  Luis Calçada, Martin Kornmesser Web and technical support: Raquel Yumi Shida Scientific consultants: Violette Impellizzeri Acknowledgements: Paul Tiede, Michael Janssen Promotion: Juan Carlos Muñoz Mateos, Oana Sandu Filming Locations: ESO Supernova (Super Nova ESO)   Produced by ESO, the European Southern Observatory

Transcript

00:00This has to be one of the most iconic astronomical images of all times.

00:05In 2019, the world got to see the first ever direct image of a supermassive black hole,

00:12the ring of light surrounding the giant in the galaxy M87.

00:16Now, the Event Horizon Telescope collaboration has released new images of this fascinating object.

00:22Stay tuned, we're in for some surprises.

00:25I'm sure you can't wait for me to show you the new images.

00:32But before I do, let's cover the basics.

00:36Taking an image of a black hole is no mean feat.

00:39Even the largest ones on the sky are so small that it takes a telescope the size of the Earth

00:45to resolve the material swirling in a death spiral around them.

00:49Enter the Event Horizon Telescope, or EHT for short.

00:54The EHT is a network of radio, or rather millimeter, telescopes, including ALMA, spread across the globe.

01:02They're combined to form one giant virtual telescope, using a technique called Very Long Baseline Interferometry.

01:09We did a whole Chasing Starlight episode about the EHT and how it works, so make sure to check that out.

01:15In 2019, the EHT made history with the image of the supermassive black hole at the center of M87, based on data taken in 2017.

01:25The data analysis process was so complicated, it took two whole years.

01:30In 2022, the team published an image of a second black hole, Sag A star, which lies at the center of our own Milky Way galaxy.

01:38But the EHT's work is by no means complete by just taking one image of each of these two black holes.

01:45By observing using different setups and at different epochs, we hope to learn much more about black holes and the physics powering them.

01:53The latest images of the M87 black hole are based on full polarization observations taken in 2017, 2018 and 2021.

02:02And who better to explain them to us than a member of the EHT team itself.

02:07Meet my colleague and friend, Violette Impelizzeri.

02:10Not only did we work at ALMA together for many years, but we also bonded over various activities and adventures.

02:17Violette is an expert on black holes and Very Long Baseline Interferometry.

02:22And she's going to help us understand the new results and why they're so important.

02:27So the first M87 image that was published in 2019 was a true breakthrough result.

02:35It was fundamentally new.

02:37We were showing for the first time the image of supermassive black hole.

02:42Because it was an extraordinary result, it needed to also be repeated.

02:46And we needed to get all the community to believe our result was real, was groundbreaking.

02:52If I had to pick my favorite astronomical result of the last decade,

02:55the M87 image would definitely be in the top three.

02:58But I have to admit that although I was stunned and seriously impressed,

03:02I was also a little bit skeptical.

03:04The image just seemed too good to be true.

03:07I mean, it looked exactly what we expected a black hole to look like.

03:12So I'm really, really happy to see these new results.

03:16In this latest publication, we're showing the results.

03:19We're showing what's come of these three completely independent observations.

03:23And what we find is that basic properties of this image, namely the size of the ring primarily,

03:29do not change for these three different epochs.

03:33The size is very important and actually is the most important characteristic.

03:38The size of the ring depends on two things.

03:40It depends on the mass of the black hole and the distance from us.

03:44Because for M87, we know very accurately from independent observations, previous observations,

03:50the size, the mass of the black hole and the distance from us.

03:53We actually predicted ahead of observing how big we expect the size of the ring to be.

03:59And our observations already in 2019 confirmed our predictions.

04:03So we already claimed back then that Einstein was right.

04:07But it was really important that we repeat this.

04:09And in the EAT and with the new paper and the new observations,

04:12we have shown in 2017, 18 and 2021, the size of the ring as seen by us is the same as constant.

04:20The size of the ring is one thing, but another feature that's striking from the image

04:25is that the lower portion of the ring appears brighter.

04:29This is due to an effect called Doppler boosting or relativistic beaming.

04:35Light from material that is travelling towards us at relativistic speeds

04:39gets boosted in intensity and appears brighter,

04:42while light from material that is travelling away from us appears dimmer.

04:46The exact location of the bright and dark parts depends on the inclination angle

04:51of the system and its disc relative to Earth.

04:54The new images of M87 show that the overall brightness distribution

04:58stays more or less constant over the three epochs,

05:01which is exactly what we would expect.

05:03So the stability of this emission is the same over long periods of time

05:08because it depends on accretion to supermassive black hole.

05:12Because the size of this ring and the position and also the mass of the black hole

05:18stays the same in our human timescales,

05:21we do expect the overall properties to actually remain the same over this period of three years.

05:27So far, so not really unexpected.

05:30But what did the team find that was so surprising?

05:33Let's take a look at one particular aspect of the observations, the polarisation.

05:40You may have heard of polarised sunglasses,

05:43but what do polarisation measurements mean in the context of a black hole?

05:48By measuring the polarisation, we can actually probe these invisible, strong magnetic fields,

05:55these superhighways.

05:56They're so strong that they actually carry the plasma around.

06:00So the magnetic fields are extremely important.

06:04So it's very important that we also understand what they look like and what they're strengthened.

06:08This is why it's so critical that we study the polarisation

06:11and the changes in the polarisation year to year.

06:14OK, so the polarisation tells us about the shape of the magnetic field,

06:19which determines how matter moves close to the black hole.

06:23If we take a look at the images taken at different epochs,

06:28we see that the polarisation changes dramatically.

06:31In 2017, the magnetic fields spiral one way.

06:35In 2018, they've all but disappeared.

06:38And by 2021, they're going in the other direction.

06:42A surprise, according to Violette.

06:44The magnitude of these changes was actually unexpected.

06:48In fact, the second epoch, the magnetic fields, i.e. the polarisation,

06:52the polarisation is extremely faint.

06:54And we do not fully understand why that is happening.

06:57We have some ideas, we have some clues, but we don't fully understand what's happening there.

07:01So it's very intriguing, it's very exciting.

07:04One of the main limitations of the EHT is the relatively small number of individual stations

07:09making up this giant virtual telescope.

07:12If you imagine the EHT as a huge block of Swiss cheese, you'd end up with more whole than actual cheesy goodness.

07:20This makes reconstructing the image of a black hole via interferometry extremely challenging

07:26and creates gaps in the data at certain spatial scales.

07:30Placing individual telescopes very far away from each other allows us to resolve very small spatial scales,

07:37such as the accretion ring around M87.

07:40While putting the telescopes close to each other allows us to uncover larger structures,

07:45such as the giant jet emanating from the black hole in M87.

07:49So one of the most obvious ways of improving the EHT is to add more antennas at different distances from each other to the network.

07:58For the last observations, the 2021, for example, we had two extra telescopes, a Kitt Peak and NOIMA.

08:05And already with these observations, we could see that they make a big difference.

08:09Because they are what we call intermediate baselines, they allowed us to see some of the extended gas

08:15that is not just the ring itself, but it's the part that connects the ring with the really, really large jet that goes far out.

08:22And bridging these two regions has been extremely challenging because these are really intermediate sizes.

08:28So one of the major outcomes actually of this paper is that we can see starting to see this intermediate gas.

08:38The publication of the first ever direct image of a black hole was not just the culmination of decades of effort,

08:44of decades of efforts and a huge accomplishment, but also the start of a whole new era of black hole research.

08:51Thanks to the ongoing efforts, not only of the EHT team, but also staff at the associated observatories and research teams worldwide,

09:00we were able to check once again and confirm the predictions of Einstein's general relativity

09:06and challenge our understanding of magnetic fields in these extreme black hole environments.

09:13On the off chance that some of you think black holes are boring, well, Violette has the last word.

09:20They're really exciting and they change over time and it's worth observing them for the long run.

09:25They tell us how they accrete, how they spew matter out, and we have still a lot to learn.

09:30There's a lot more coming, besides our frequencies, we're planning to have movies,

09:34we're planning to have more antennas, maybe send antennas into space.

09:37So the EHT is really, you know, it's a long path to go, a lot more to discover.

09:43doing something that's the way that we can't detect otherwise, but hopefully think about removes a large compare to 1080

09:51if you're and that's enough.

09:52Yeah, it's going well in the next couple of results, and we'll do a Alberta horizon.

09:56All the vacations that solve the pandemic measures were very painful and valtые,

09:58through which have missed the Os West.

Imagery Of M87's Black Hole Shows Polarity Flip - ESO Explains

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