The first image of the supermassive black hole at the center of our own galaxy has been unveiled at a press conference. This result shows that the object is a black hole and provides valuable clues about the workings of such giants, which are thought to reside at the center of most galaxies. The image was produced by a global research team using observations from a worldwide network of radio telescopes.
The image shows a large object at the center of our universe. The center of the Milky Way was previously seen by scientists as being invisible, compact, and massive. This strongly suggested that this object is a black hole, and today's image provides the first direct visual evidence of it.
We can't see the black hole itself because it is completely dark, but glowing gas around it shows a telltale sign: a dark central region surrounded by a bright, ring-like structure. The black hole is four million times larger than the sun and it is reflected in the new view.
The size of the ring agreed with predictions from Einstein's theory of general relativity.
The black hole appears to be the same size as a donut in the sky. To image it, the team created the powerful EHT, which linked together eight existing radio observatories across the planet to form a single virtual telescope. Sgr A* was observed by the EHT for many hours in a row, similar to using a long exposure time on a camera.
The support of the most sensitive instruments in radio astronomy is what made the image of Sgr A* so special. The 1.3mm Band 6 receivers on the ALMA were designed by the Central Development Laboratory at the US National Science Foundation.
"We are very proud at CDL to have provided some critical technology to support this amazing discovery by the EHT collaboration, and we are proud to have played a part in making the research and the results possible," said the Director of CDL. This turned the telescope into a single dish with an effective diameter of 85 meters. The Large Millimeter Telescope in Mexico, the Submillimeter Telescope in Arizona, and the South Pole Telescope in Antarctica were all developed at CDL.
The first image of a black hole, called M87*, at the center of the more distant Messier 87 galaxy was released in 2019.
The two black holes are close to each other, even though the black hole in our galaxy is less massive.
Even though Sgr A* is closer to us, this achievement was more difficult than M87*. The gas in the vicinity of the black holes moves at the same time as Chi-kwan explains. In the smaller Sgr A*, gas takes days to weeks to go to the larger M87. This means the gas around Sgr A* was changing quickly as the EHT Collaboration was observing it, like trying to take a clear picture of a puppy chasing its tail.
The researchers had to develop new tools to account for the gas movement around Sgr A*. Sgr A* was not an easy target, with nearly all images looking the same. The image of the Sgr A* black hole is an average of the images taken by the team.
The effort was made possible by the ingenuity of more than 300 researchers from 80 institutes around the world. In addition to developing complex tools to overcome the challenges of Sgr A*, the team worked rigorously for five years, using supercomputers to combine and analyze their data, and build an unprecedented library of simulation black holes to compare with the observations.
This work clearly shows the importance of using radio, millimeter and sub millimeter frequencies to understand the most extreme environments in the universe. The addition of ALMA gave the necessary sensitivity to make the observation. Combining all the data from facilities all over the world with ALMA as the anchor for all these facilities provided the sensitivity and resolution needed to make these types of discoveries. This is just the beginning. ALMA is planning a large increase to its sensitivity in the next decade, which will lead to even more profound discoveries in the universe.
Scientists are excited to finally have images of two black holes of different sizes, which will allow them to understand how they compare and contrast. New data has begun to be used to test theories and models of how gas behaves around black holes. This process is thought to play a key role in shaping the formation and evolution of galaxies.
Keiichi Asada from the Institute of Astronomy and Astrophysics, Sinica, Taipei, said that they can study the differences between the two black holes to find out more about how this important process works.
More telescopes than ever before were included in a major observation campaign. Scientists will be able to share even more impressive images and movies of black holes thanks to the ongoing expansion of the EHT network.
The ALMA Development Program approved a multi-million dollar upgrade for the Observatory's Band 6 receivers. The upgrade will increase the quantity and quality of science measured in the wavelength range between 1.4mm and 1.1mm, which will provide research projects like those at EHT with better sensitivity than ever before, and ultimately more accurate and more efficient science results. The Next Generation Very Large Array received positive support from the Astro 2020 decadal survey. The ngVLA is slated to become the ultimate black hole hunting machine due to its high priority goals in astronomy and astrophysics.
The new results from EHT show how far astronomy has come and confirm that there is still so much we haven't seen.
More information: The Astrophysical Journal Letters: iopscience.iop.org/journal/2041-8205 Journal information: Astrophysical Journal Letters Citation: Astronomers reveal first image of the black hole at the heart of our galaxy (2022, May 12) retrieved 12 May 2022 from https://phys.org/news/2022-05-astronomers-reveal-image-black-hole.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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