EHT: Astronomers Capture First Image of a Black Hole

[bystander]

Astronomers Capture First Image of a Black Hole
Event Horizon Telescope | NSF | ESO | ALMA | 2019 Apr 10

An international collaboration presents paradigm-shifting observations of the gargantuan black hole at the heart of distant galaxy M 87

Scientists have obtained the first image of a black hole, using Event Horizon Telescope observations of the center of the galaxy M87. The image shows a bright ring formed as light bends in the intense gravity around a black hole that is 6.5 billion times more massive than the Sun. This long-sought image provides the strongest evidence to date for the existence of supermassive black holes and opens a new window onto the study of black holes, their event horizons, and gravity. Credit: Event Horizon Telescope Collaboration

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The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. Today, in coordinated press conferences across the globe, EHT researchers reveal that they have succeeded, unveiling the first direct visual evidence of a supermassive black hole and its shadow.

This breakthrough was announced today in a series of six papers published in a special issue of The Astrophysical Journal Letters. The image reveals the black hole at the centre of Messier 87 [1], a massive galaxy in the nearby Virgo galaxy cluster. This black hole resides 55 million light-years from Earth and has a mass 6.5 billion times that of the Sun [2].

The EHT links telescopes around the globe to form an unprecedented Earth-sized virtual telescope [3]. The EHT offers scientists a new way to study the most extreme objects in the Universe predicted by Einstein’s general relativity during the centenary year of the historic experiment that first confirmed the theory [4]. ...

First M87 Event Horizon Telescope Results.

1. The Shadow of the Supermassive Black Hole ~ EHT Collaboration et al
   • Astrophysical Journal Letters 875(1):L1 (2019 Apr 10) DOI: 10.3847/2041-8213/ab0ec7
   • arXiv.org > astro-ph > arXiv:1906.11238 > 26 Apr 2019
2. Array and Instrumentation ~ EHT Collaboration et al
   • Astrophysical Journal Letters 875(1):L2 (2019 Apr 10) DOI: 10.3847/2041-8213/ab0c96
   • arXiv.org > astro-ph > arXiv:1906.11239 > 26 Apr 2019
3. Data Processing and Calibration ~ EHT Collaboration et al
   • Astrophysical Journal Letters 875(1):L3 (2019 Apr 10) DOI: 10.3847/2041-8213/ab0c57
   • arXiv.org > astro-ph > arXiv:1906.11240 > 26 Apr 2019
4. Imaging the Central Supermassive Black Hole ~ EHT Collaboration et al
   • Astrophysical Journal Letters 875(1):L4 (2019 Apr 10) DOI: 10.3847/2041-8213/ab0e85
   • arXiv.org > astro-ph > arXiv:1906.11241 > 26 Apr 2019
5. Physical Origin of the Asymmetric Ring ~ EHT Collaboration et al
   • Astrophysical Journal Letters 875(1):L5 (2019 Apr 10) DOI: 10.3847/2041-8213/ab0f43
   • arXiv.org > astro-ph > arXiv:1906.11242 > 26 Apr 2019
6. The Shadow and Mass of the Central Black Hole ~ EHT Collaboration et al
   • Astrophysical Journal Letters 875(1):L6 (2019 Apr 10) DOI: 10.3847/2041-8213/ab1141
   • arXiv.org > astro-ph > arXiv:1906.11243 > 26 Apr 2019

[bystander]

Black Hole Image Makes History
NASA | JPL-Caltech | Chandra | NuSTAR | Swift | 2019 Apr 10

CfA Plays Central Role In Capturing Landmark Black Hole Image
Harvard Smithsonian Center for Astrophysics | 2019 Apr 10

"Virtual Telescope" Produces First Direct Image of a Black Hole
Massachusetts Institute of Technology | 2019 Apr 10

Chasing Einstein's Shadow
University of Arizona | 2019 Apr 10

A 30-metre eye in the Sierra Nevada
Institute of Millimeter Radio Astronomy (IRAM) | Max Planck Gesellschaft | 2019 Apr 10

Astronomers Capture First Image of a Black Hole
Max Planck Institute for Radio Astronomy | 2019 Apr 10

Astronomers Capture First Image of a Black Hole
Goethe University | 2019 Apr 10

Chandra Captures X-rays in Coordination with EHT
NASA | SAO | Chandra X-ray Observatory | 2019 Apr 10

[neufer]

Astronomers Capture First Image of a Black Hole
Event Horizon Telescope | NSF | ESO | ALMA | 2019 Apr 10

An international collaboration presents paradigm-shifting observations of the gargantuan black hole at the heart of distant galaxy M 87

Scientists have obtained the first image of a black hole, using Event Horizon Telescope observations of the center of the galaxy M87. The image shows a bright ring formed as light bends in the intense gravity around a black hole that is 6.5 billion times more massive than the Sun. This long-sought image provides the strongest evidence to date for the existence of supermassive black holes and opens a new window onto the study of black holes, their event horizons, and gravity. Credit: Event Horizon Telescope Collaboration

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The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. Today, in coordinated press conferences across the globe, EHT researchers reveal that they have succeeded, unveiling the first direct visual evidence of a supermassive black hole and its shadow.

This breakthrough was announced today in a series of six papers published in a special issue of The Astrophysical Journal Letters. The image reveals the black hole at the centre of Messier 87 , a massive galaxy in the nearby Virgo galaxy cluster. This black hole resides 55 million light-years from Earth and has a mass 6.5 billion times that of the Sun.

The EHT links telescopes around the globe to form an unprecedented Earth-sized virtual telescope. The EHT offers scientists a new way to study the most extreme objects in the Universe predicted by Einstein’s general relativity during the centenary year of the historic experiment that first confirmed the theory. ...

Click to play embedded YouTube video.

Here it is in motion: https://apod.nasa.gov/apod/ap190410.html

M87 BH diameter: 1.48 microarcseconds
Sagittarius A* BH diameter: 1.98 microarcseconds

<<In April 2019, the Event Horizon Telescope released measurements of M87's supermassive black hole mass as 6.5 × 10⁹ M_☉. A rotating disk of ionized gas surrounds the black hole, and is roughly perpendicular to the relativistic jet. The disk rotates at velocities of up to roughly 1,000 km/s, and spans a maximum diameter of 0.12 parsecs (0.39 light-years). Gas accretes onto the black hole at an estimated rate of one solar mass every ten years (about 90 earth masses per day). Observation suggests that the black hole may be displaced from the galactic center by about seven parsecs (23 light-years). The displacement is in the opposite direction of the one-sided jet, which may indicate that the black hole was accelerated away by the jet. Another possibility is that the change in location occurred during the merger of two supermassive black holes.>>

[Psnarf]

Hubble visual image of Messier 87:


Earth-wide radio telescope array image M87's black hole:


The jet suggests we view M87 from above at an angle from its axis of rotation. Does that explain the oval shape of the hole? If we viewed a black hole from directly above the axis of rotation, folks smarter than I suggest that would violate Einstein's Relativity law.

[Ann]

Hubble visual image of Messier 87:


Earth-wide radio telescope array image M87's black hole:


The jet suggests we view M87 from above at an angle from its axis of rotation. Does that explain the oval shape of the hole? If we viewed a black hole from directly above the axis of rotation, folks smarter than I suggest that would violate Einstein's Relativity law.

Interesting comparison of pictures, Psnarf. I can easily imagine the black hole generating energy that creates the jet that we can see in the visual image.

You said,

If we viewed a black hole from directly above the axis of rotation, folks smarter than I suggest that would violate Einstein's Relativity law.

A person as stupid as I would like to know why that would violate Einstein's Relativity law.

Ann

[orin stepanek]

On the lighter side; looks like a yummy doughnut!

[Psnarf]

I meant to refer to the awe-inspiring image of the day. If the shadow is oval-shaped when viewed from above the axis of rotation, that would violate Einstein's gravitivity. If we use the angle of the jet, which must be the same angle from which we view the accretion disc, unless black holes wobble, that viewing angle explains the non-circular shadow. If the jet were pointed directly at Earth, the radio image would indeed show a circular shadow. The radius of the shadow must be the same at any point on the sphere. If the shadow is not a sphere, all bets are off, according to my feeble understanding of this sort of nonsense (to me).
The notion parroted by the teevee teleprompter readers that gravity pulls photons changing direction of propagation is strange to me. Methinks that close to the holy blackness spacetime itself gets wacky. Get closer than the event horizon, and the dimensions of space get interchanged with time. Photons approaching the tangent of the shadow sphere follow a straight line; it is spacetime itself that is shaped like a sphere. All the photons that ever approached the tangent from any direction are still going round and round on the surface of the shadow, are they not?
Mebrayne Hertz

[bystander]

The Galaxy, the Jet, and the Black Hole (2019 Apr 27)

The Giant Galaxy Around the Giant Black Hole
NASA | JPL-Caltech | Spitzer | 2019 Apr 25

Spitzer Captures M87 (EHT) ~ Credit: NASA/JPL-Caltech/IPAC/EHT Collaboration

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On April 10, 2019, the Event Horizon Telescope (EHT) unveiled the first-ever image of a black hole's event horizon, the area beyond which light cannot escape the immense gravity of the black hole. That giant black hole, with a mass of 6.5 billion Suns, is located in the elliptical galaxy Messier 87 (M87). EHT is an international collaboration whose support in the U.S. includes the National Science Foundation.

This image from NASA's Spitzer Space Telescope shows the entire M87 galaxy in infrared light. The EHT image, by contrast, relied on light in radio wavelengths and showed the black hole's shadow against the backdrop of high-energy material around it.

Located about 55 million light-years from Earth, M87 has been a subject of astronomical study for more than 100 years and has been imaged by many NASA observatories, including the Hubble Space Telescope, the Chandra X-ray Observatory and NuSTAR. In 1918, astronomer Heber Curtis first noticed "a curious straight ray" extending from the galaxy’s center. This bright jet of high-energy material, produced by a disk of material spinning rapidly around the black hole, is visible in multiple wavelengths of light, from radio waves through X-rays. When the particles in the jet impact the interstellar medium (the sparse material filling the space between stars in M87), they create a shockwave that radiates in infrared and radio wavelengths of light but not visible light. In the Spitzer image, the shockwave is more prominent than the jet itself.

The brighter jet, located to the right of the galaxy's center, is traveling almost directly toward Earth. Its brightness is amplified due to its high speed in our direction, but even more so because of what scientists call "relativistic effects," which arise because the material in the jet is traveling near the speed of light. The jet's trajectory is just slightly offset from our line of sight with respect to the galaxy, so we can still see some of the length of the jet. The shockwave begins around the point where the jet appears to curve down, highlighting the regions where the fast-moving particles are colliding with gas in the galaxy and slowing down.

The second jet, by contrast, is moving so rapidly away from us that the relativistic effects render it invisible at all wavelengths. But the shockwave it creates in the interstellar medium can still be seen here.

Located on the left side of the galaxy's center, the shockwave looks like an inverted letter "C." While not visible in optical images, the lobe can also be seen in radio waves, as in this image from the National Radio Astronomy Observatory's Very Large Array. ...

[bystander]

Telescopes in Space for Even Sharper Images of Black Holes
Radboud University, Netherlands | 2019 May 06

In space, the EHI has a resolution more than five times that of the EHT on earth, and images can be reconstructed with higher fidelity. Top left: Model of Sagittarius A* at an observation frequency of 230 GHz. Top left: Simulation of an image of this model with the EHT. Bottom left: Model of Sagittarius A* at an observation frequency of 690 GHz. Bottom right: Simulation of an image of this model with the EHI.

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Astronomers have just managed to take the first image of a black hole, and now the next challenge facing them is how to take even sharper images, so that Einstein's Theory of General Relativity can be tested. Radboud University astronomers, along with the European Space Agency (ESA) and others, are putting forward a concept for achieving this by launching radio telescopes into space. They have published their plans in the scientific journal Astronomy & Astrophysics.

The idea is to place two or three satellites in circular orbit around the Earth to observe black holes. The concept goes by the name Event Horizon Imager (EHI). In their new study, the scientists present simulations of what images of the black hole Sagittarius A* would look if they were taken by satellites like these.

"There are lots of advantages to using satellites instead of permanent radio telescopes on Earth, as with the Event Horizon Telescope (EHT)," says Freek Roelofs, a PhD candidate at Radboud University and the lead author of the article. "In space, you can make observations at higher radio frequencies, because from Earth these are filtered out by the atmosphere. The distances between the telescopes in space are also larger. This allows us to take a big step forward. We would be able to take images with a resolution more than five times what is possible with the EHT."

Sharper images of a black hole will lead to better information that could be used to test Einstein's Theory of General Relativity in greater detail. "The fact that the satellites are moving round the Earth makes for considerable advantages," Radio Astronomy Professor Heino Falcke says. "With them, you can take near perfect images to see the real details of black holes. If small deviations from Einstein's theory occur, we should be able to see them."

The EHI will also be able to image about five additional black holes that are smaller than the black holes that the EHT is currently focussing on. The latter are Sagittarius A* at the centre of our Milky Way and M87* at the centre of Messier 87, a massive galaxy in the Virgo Cluster. ...

Simulations of Imaging the Event Horizon of Sagittarius A* from Space ~ Freek Roelofs et al

• Astronomy & Astrophysics (accepted 06 Apr 2019) DOI: 10.1051/0004-6361/201732423
• arXiv.org > astro-ph > arXiv:1904.04934 > 09 Apr 2019

[bystander]

Wobbling Shadow of the M87* Black Hole
Event Horizon Telescope | 2020 Sep 23

Analysis of the Event Horizon Telescope observations from 2009-2017 reveals turbulent evolution of the M87* black hole image

Snapshots of the M87* black hole obtained through imaging / geometric modeling, and the EHT array of telescopes in 2009-2017. The diameter of all rings is similar, but the location of the bright side varies. Credit: M. Wielgus, D. Pesce & the EHT Collaboration

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In 2019, the Event Horizon Telescope (EHT) Collaboration delivered the first image of a black hole, revealing M87* — the supermassive object in the center of the M87 galaxy. The EHT team has now used the lessons learned last year to analyze the archival data sets from 2009-2013, some of them not published before. The analysis reveals the behavior of the black hole image across multiple years, indicating persistence of the crescent-like shadow feature, but also variation of its orientation—the crescent appears to be wobbling. ...

The EHT is a global array of telescopes, performing synchronized observations using the technique of Very Long Baseline Interferometry (VLBI). Together they form a virtual Earth-sized radio dish, providing a uniquely high image resolution. ... In 2009-2013 M87* was observed by early-EHT prototype arrays, with telescopes located at three geographical sites in 2009-2012, and four sites in 2013. In 2017 the EHT reached maturity with telescopes located at five distinct geographical sites across the globe. ...

The 2009-2013 observations consist of far less data than the ones performed in 2017, making it impossible to create an image. Instead, the EHT team used statistical modeling to look at changes in the appearance of M87* over time. While no assumptions about the source morphology are made in the imaging approach, in the modeling approach the data are compared to a family of geometric templates, in this case rings of non-uniform brightness. A statistical framework is then employed to determine if the data are consistent with such models and to find the best-fitting model parameters. ...

But while the crescent diameter remained consistent, the EHT team found that the data were hiding a surprise: the ring wobbles, and that means big news for scientists. For the first time, they can get a glimpse of the dynamical structure of the accretion flow so close to the black hole’s event horizon, in extreme gravity conditions. Studying this region holds the key to understanding phenomena such as relativistic jet launching, and will allow scientists to formulate new tests of the theory of General Relativity. ...

M87*'s Shadow Is Wobbling and Has Been for a While
Harvard Smithsonian Center for Astrophysics | 2020 Sep 23

The Ring around the M87* Black Hole Shadow Glitters
Max Planck Institute for Radio Astronomy | 2020 Sep 23

Monitoring the Morphology of M87* in 2009-2017 with the Event Horizon Telescope ~ Maciek Wielgus et al

• Astrophysical Journal 901(1):67 (2020 Sep 20) DOI: 10.3847/1538-4357/abac0d

[neufer]

Wobbling Shadow of the M87* Black Hole
Event Horizon Telescope | 2020 Sep 23

Analysis of the Event Horizon Telescope observations from 2009-2017 reveals turbulent evolution of the M87* black hole image

Snapshots of the M87* black hole obtained through imaging / geometric modeling, and the EHT array of telescopes in 2009-2017. The diameter of all rings is similar, but the location of the bright side varies. Credit: M. Wielgus, D. Pesce & the EHT Collaboration

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In 2019, the Event Horizon Telescope (EHT) Collaboration delivered the first image of a black hole, revealing M87* — the supermassive object in the center of the M87 galaxy. The 2009-2013 observations consist of far less data than the ones performed in 2017, making it impossible to create an image. Instead, the EHT team used statistical modeling to look at changes in the appearance of M87* over time. While no assumptions about the source morphology are made in the imaging approach, in the modeling approach the data are compared to a family of geometric templates, in this case rings of non-uniform brightness. A statistical framework is then employed to determine if the data are consistent with such models and to find the best-fitting model parameters. ...

But while the crescent diameter remained consistent, the EHT team found that the data were hiding a surprise: the ring wobbles, and that means big news for scientists. For the first time, they can get a glimpse of the dynamical structure of the accretion flow so close to the black hole’s event horizon, in extreme gravity conditions. Studying this region holds the key to understanding phenomena such as relativistic jet launching, and will allow scientists to formulate new tests of the theory of General Relativity. ...

Diddy Wishingwell

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<<Tipping an egg-shaped Weeble causes a weight located at the bottom-center to be lifted off the ground. Once released, gravity brings the Weeble back into an upright position.

The catchphrase "Weebles wobble, but they don't fall down" was used in advertising during their rise in popularity in the 1970s and during successive relaunches in the early 2000s.>>

[bystander]

Black Hole Shadow Puts General Relativity to the Test
Institute for Advanced Studies | 2020 Oct 01

Click to play embedded YouTube video.

M87 - Supermassive Black Hole Simulation ~ Credit: Lia Medeiros, IAS, BH PIRE

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If a picture is worth a thousand words, what might the first horizon-scale image of a black hole tell us? A new paper by researchers from the Event Horizon Telescope (EHT) collaboration, which famously imaged M87’s central black hole, has provided a number of enlightening answers. Based on an analysis of the black hole’s shadow, the team conducted a unique test of general relativity, deepening understanding about the unusual properties of black holes and ruling out many alternatives. ...

The intense gravity of a black hole curves spacetime, acting as a magnifying glass and causing the black hole shadow to appear larger. By measuring this visual distortion, the research team found that the size of the black hole shadow corroborates the predictions of general relativity. A test of gravity at the edge of a supermassive black hole represents a first for physics and offers further proof that Einstein’s theory remains intact even under the most extreme conditions. ...

The black hole shadow is unlike the shadows encountered in everyday life. Whereas a physical object casts a shadow by preventing light from passing through it, a black hole can create the effect of a shadow by siphoning light towards itself. While light cannot escape from the interior of a black hole, it is possible—though unlikely—for light to escape from the region surrounding the event horizon, depending on its trajectory. The result is a murky no man’s land just beyond the point of no return, which appears to observers as a shadow. ...

Einstein's Description of Gravity Just Got Much Harder to Beat
University of Arizona, Tucson | Event Horizon Telescope | 2020 Oct 01

Gravitational Test beyond the First Post-Newtonian Order
with the Shadow of the M87 Black Hole ~ EHT Collaboration: Dimitrios Psaltis et al

• Physical Review Letters 125(14):1104 (Oct 2020) DOI: 10.1103/PhysRevLett.125.141104

A Parametric Model for the Shapes of Black Hole Shadows
in Non-Kerr Spacetimes ~ Lia Medeiros, Dimitrios Psaltis, Feryal Özel

• Astrophysical Journal 896(1):7 (2020 Jun 10) DOI: 10.3847/1538-4357/ab8bd1
• arXiv.org > astro-ph > arXiv:1907.12575 > 29 Jul 2019 (v1), 21 Apr 2020 (v2)

[bystander]

A Sharper Look at the First Image of a Black Hole
NOIRLab Photo Release | 2023 Apr 13

Machine learning reconstructs new image of Messier 87 from Event Horizon Telescope data

Credit: L. Medeiros (Institute for Advanced Study), D. Psaltis (Georgia Tech), T. Lauer (NOIRLab), and F. Ozel (Georgia Tech)

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A team of researchers ... has developed a new machine-learning technique to enhance the fidelity and sharpness of radio interferometry images. To demonstrate the power of their new approach, which is called PRIMO, the team created a new, high-fidelity version of the iconic Event Horizon Telescope's image of the supermassive black hole at the center of Messier 87, a giant elliptical galaxy located 55 million light-years from Earth.

The iconic image of the supermassive black hole at the center of Messier 87 has received its first official makeover, thanks to a new machine-learning technique known as PRIMO. This new image better illustrates the full extent of the object’s dark central region and the surprisingly narrow outer ring. To achieve this result, a team of researchers used the original 2017 data obtained by the Event Horizon Telescope (EHT) collaboration and created a new image that, for the first time, represents the full resolution of the EHT.

PRIMO, which stands for principal-component interferometric modeling, was developed by EHT members Lia Medeiros (Institute for Advanced Study), Dimitrios Psaltis (Georgia Tech), Tod Lauer (NSF’s NOIRLab), and Feryal Ozel (Georgia Tech). A paper describing their work is published in The Astrophysical Journal Letters.

In 2017 the EHT collaboration used a network of seven radio telescopes at different locations around the world to form an Earth-sized virtual telescope with the power and resolution capable of observing the “shadow” of a black hole’s event horizon. Though this technique allowed astronomers to see remarkably fine details, it lacked the collecting power of an actual Earth-sized telescope, leaving gaps in the data. The researchers’ new machine-learning technique helped fill in those gaps. ...

Sharper Look at M87 Black Hole
Institute for Advanced Study (IAS) | 2023 Apr 13

The Image of the M87 Black Hole Reconstructed with PRIMO ~ Lia Medeiros et al

• Astrophysical Journal Letters 947(1):L7 (2023 Apr 10) DOI: 10.3847/2041-8213/acc32d

Principal-component Interferometric Modeling (PRIMO), an Algorithm for EHT Data.
I. Reconstructing Images from Simulated EHT Observations ~ Lia Medeiros et al

• Astrophysical Journal 943(2):144 (2023 Feb 01) DOI: 10.3847/1538-4357/acaa9a
• arXiv > astro-ph > arXiv:2208.01667 > 02 Aug 2022 (v1), 16 Dec 2022 (v2)

[bystander]

Giant Galaxy Seen in 3D by Hubble and Keck
NASA | GSFC | STScI | HubbleSite | 2023 Apr 13

A photo of the huge elliptical galaxy M87 [left] is compared to its three-dimensional shape as gleaned from meticulous observations made with the Hubble and Keck telescopes [right]. Because the galaxy is too far away for astronomers to employ stereoscopic vision, they instead followed the motion of stars around the center of M87, like bees around a hive. This created a three-dimensional view of how stars are distributed within the galaxy.

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Hubble and Keck Telescopes Assemble a 3D View of a Giant Galaxy
Credit: NASA, ESA, J. Olmsted (STScI), F. Summers (STScI), C. Ma (UC Berkeley)

Though we live in a vast three-dimensional universe, celestial objects seen through a telescope look flat because everything is so far away. Now for the first time, astronomers have measured the three-dimensional shape of one of the biggest and closest elliptical galaxies to us, M87. This galaxy turns out to be "triaxial," or potato-shaped. This stereo vision was made possible by combining the power of NASA's Hubble Space Telescope and the ground-based W. M. Keck Observatory on Maunakea, Hawaii.

In most cases, astronomers must use their intuition to figure out the true shapes of deep-space objects. For example, the whole class of huge galaxies called "ellipticals" look like blobs in pictures. Determining the true shape of giant elliptical galaxies will help astronomers understand better how large galaxies and their central large black holes form.

Scientists made the 3D plot by measuring the motions of stars that swarm around the galaxy's supermassive central black hole. The stellar motion was used to provide new insights into the shape of the galaxy and its rotation, and it also yielded a new measurement of the black hole's mass. Tracking the stellar speeds and position allowed researchers to build a three-dimensional view of the galaxy. ...

M87 in 3D: New view of galaxy helps pin down mass of the black hole at its core
University of California, Berkeley | 2023 Apr 13

First Ever 3D Map of Messier 87 Galaxy Assembled
W.M. Keck Observatory | 2023 Apr 13

Keck Integral-field Spectroscopy of M87 Reveals an Intrinsically
Triaxial Galaxy and a Revised Black Hole Mass ~ Emily R. Liepold et al

• Astrophysical Journal Letters 945(2):L35 (2023 Mar 10) DOI: 10.3847/2041-8213/acbbcf
• arXiv > astro-ph > arXiv:2302.07884 > 15 Feb 2023 (v1), 10 Apr 2023 (v2)