Astrophysicists at the Harvard and Smithsonian Centers for Astrophysics (CfA) have proposed a way to observe what could be the second-closest supermassive black hole to Earth: a giant three million times the mass of the Sun, hosted by the dwarf galaxy Leo THE.
The supermassive black hole, dubbed Leo I*, was first proposed by a team of independent astronomers in 2021. The team noted that the star’s speed increases as it approaches the galactic center: Evidence for the existence of black holes – but direct imaging of emission from black holes is impossible.
Now, CfA astrophysicists Fabio Paccucci and Avi Loeb have found a new way to decipher the existence of supermassive black holes.
The results of their research were published today in Astrophysics journal letter.
Why is it so difficult to observe black holes?
“Supermassive black holes are very elusive things, and sometimes they even enjoy playing hide and seek with us,” explained Fabio Paccucci, lead author of the study.
Light rays cannot escape the event horizon, but the surroundings can become very bright if enough matter enters gravity well. But if a black hole doesn’t accumulate mass, then it doesn’t emit light and becomes impossible. Find it with our telescopes.”
That’s the challenge with Leo I*, a dwarf galaxy that lacks available gas for coalescence and is often described as a fossil. However, these difficulties have not dampened astronomers’ hopes of observing this supermassive black hole.
“In our study, we suggest that the small amount of mass lost by stars orbiting black holes may provide the accretion rate needed to observe them,” Bacucci said.
“Old stars get really big and red – we call them red giant stars. Red giants usually have strong winds that carry some of their mass into the environment. The space around Leo I* appears to contain enough of these old stars to make it visible.”
Notes will reveal groundbreaking information
Avi Loeb, co-author of the study, said “tracking early lions* could be game-changing.” “It would be the second supermassive black hole closest to the center of our galaxy, with a very similar mass but hosted by a galaxy a thousand times smaller than the Milky Way.
This fact challenges everything we know about how galaxies and their supermassive black holes co-evolve. How could such a big child be born to thin parents? “
Decades of research have shown that most massive galaxies host supermassive black holes at their centers and that the mass of these black holes is one-tenth of a percent of the total mass of the globe of stars around them.
“In the case of Leo I*, we would expect a much smaller black hole,” Loeb said. In contrast, Leo I* appears to have a black hole several million times the mass of the Sun, similar to the Milky Way. guest. It is exciting. Because science usually advances further when the unexpected happens.
Currently, the team is still working on creating images of black holes. They obtained telescope time at the Chandra X-ray Observatory and Very Large Array Radio Telescope in New Mexico and are currently analyzing the new data.
Bacucci concluded: “Leo I* played hide and seek, but he gave off so much radiation that he went unnoticed for a long time.”
