by The second image of the first black hole ever seen by mankind shows that its shadow lasts a year.
The newly released image of the supermassive black hole at the heart of the galaxy Messier 87 (M87) was captured by the Event Horizon Telescope (EHT) on April 21, 2018, one year and 10 days after it was first photographed.
Just like the April 2017 image, this second picture of the supermassive black hole, known as M87*, shows a glowing golden ring that shows material swirling around the black hole being heated to extreme temperatures. Still at the heart of this ring is a dark shadow, as predicted in Einstein’s 1915 theory of gravity, called general relativity.
“A fundamental requirement of science is to be able to reproduce results,” Keiichi Asada, a research fellow of the Academia Sinica Institute for Astronomy and Astrophysics, said in a statement. “The confirmation of the ring in a completely new data set is a huge milestone for our collaboration and a strong indication that we are looking at the shadow of a black hole and the matter orbiting around it.”
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The new image of this supermassive black hole confirms the accuracy of this theory of gravity, which predicts that the width of M87* should remain the same as long as its mass does not change significantly, thus confirming that there is indeed a black hole radius. attached to its mass.
The image also confirms that there have been some changes in the brightness of the disk, which is connected to the turbulence in the material around the black hole and is gradually feeding it.
M87* in 2017 and 2018: What changed and what stayed the same
Located 55 million light-years from Earth at the heart of the galaxy M87, the mass of the supermassive black hole M87* is equivalent to about 6.5 billion suns.
M87* powers the elliptical galaxy’s bright, active galactic nucleus (AGN) as it gradually feeds on the surrounding material, heating what it doesn’t consume with powerful magnetic fields funneling material to its poles before bursting out onto almost the speed of light.
M87* made history when it was first imaged by the EHT on April 11, 2017. Further data analysis of the M87* EHT image showed how the light around the black hole was polarized, giving clues to the structure of the magnetic fields jets and the nature of the heated gas, or plasma, surrounding the supermassive black hole.
The 2017 and 2018 images of M87* are remarkably similar, with the bright rings around the supermassive black hole remaining the same size.
This is an important observation because it shows that since the mass of this supermassive black hole has not changed significantly, and the diameter of its outer layer has not, the light trapping surface known as the event horizon acts as the outer boundary of the black hole. hole. This helps to confirm the proposition obtained from general relativity that the diameter of a black hole depends on its mass.
“One of the remarkable properties of a black hole is that its radius depends very much on one quantity: Its mass,” said NASA Jet Propulsion Laboratory scientist Nitika Yadlapalli Yurk. “Since M87* is not accreting matter (which would increase its mass) at a rapid rate, general relativity tells us that its radius will remain fairly unchanged throughout human history. It is quite exciting to see that our details of this prediction.”
Scientists expect that the black hole M87* is not accreting material fast enough for its growth to be visible over human lifetimes, and this new image also helps to confirm that this is likely to be the case.
However, that does not mean that there is no change in the M87* between the two EHT closes. In the new image, the brightest peak of the ring around the black hole has shifted 30 degrees counterclockwise. This is something the EHT team expected to see and confirms the diversity of turbulent matter around the black hole.
“The biggest shift in the brightness peak around the ring is something we actually predicted when we published the first results in 2019,” said Academia Sinica Institute of Astronomy postdoctoral fellow Britt Jeter. “Although general relativity says that the size of the ring should remain fairly fixed, the emission from the turbulent turbulent disk around the black hole will cause the brightest part of the ring to be around a common centre.
“The amount of wobble we see over time is something we can use to test our theories for the magnetic field and the plasma environment around the black hole.”
What else for the supermassive black hole M87*?
The first image of M87* and the in-depth analysis of the data used to construct it ushered in a new era of black hole investigation and also gave scientists a new laboratory to test general relativity.
The next step in these investigations was to collect repeated observations of this supermassive black hole, and this new image marked the EHT’s first use of data from M87* after 2017.
The EHT was given a helping hand in collecting new and improved images of M87* in 2018, when the Greenland Telescope, five months after its completion in the Arctic Circle, joined the other antennas in the array comprising this telescope on the size of the Universe. This improved the fidelity of the EHT image and its coverage of the sky, particularly oriented north and south.
Repeated observations of M87* also allow the EHT to be used to test cutting-edge developments in an astronomical technique called high-frequency radio interference and independent imaging and modeling techniques.
“The inclusion of the Greenland Telescope in our series fills critical gaps in our Earth-enhanced telescope,” said Instituto de Astrofísica de Andalucía PhD candidate Rohan Dahale. “The inclusion of the Greenland Telescope in our series fills critical gaps in our Earth-sized telescope.”
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The EHT continued to monitor M87* after 2018, with further observations in 2021 and 2022, with the next observation of M87* planned by the EHT for the first half of this year.
One thing astronomers will be hoping to see in the post-2018 observations is the jet of material emerging from M87*, which the relatively advanced EHT array was unable to see 6 years ago.
“There are improvements to the array in 2021, 2022, and the upcoming observations from 2024, fueling our enthusiasm to push the limits of black hole astrophysics, Dahale concluded.
The team’s research and new images of M87* are published in the journal Astronomy & Astrophysics.
