Black holes are one of the most frightening and mysterious objects in the known universe. These gravitational giants form when a massive star undergoes gravitational collapse at the end of its life and sheds its outer layers in a massive explosion (supernova).
On the other hand, the stellar remnant becomes so dense that the curvature of space-time becomes infinite near it, and its gravity is so strong that nothing (not even light) can escape its surface. This makes it impossible to observe them using conventional optical telescopes that study objects in visible light.
As a result, astronomers usually look for black holes at invisible wavelengths or by observing their effects on nearby objects.
After referencing Gaia Data Release 3 (DR3), a team of astronomers led by the University of Alabama in Huntsville (UAH) recently observed a black hole in the backyard of space. As their study explains, this massive black hole is about 12 times more massive than the Sun and is about 1,550 light-years away from Earth.
Because of its mass and relative proximity, this black hole presents an opportunity for astrophysicists.
The research was led by Dr. Sukanya Chakrabarti, Pei-Ling Chan Endowed Chair of the Department of Physics, UAH. She was attended by astronomers from the Carnegie Institute of Science, Rochester Institute of Technology, the SETI Institute Carl Sagan Center, University of California, Santa Cruz, University of California, Berkeley, University of Notre Dame, Wisconsin-Milwaukee, Hawaii, and Yale University Observatories. .
A paper describing their findings was recently published online, astrophysics journal.
Black holes are of particular interest to astronomers because they offer an opportunity to study the laws of physics under the most extreme conditions. In some cases, they also play an important role in the formation and evolution of galaxies, such as the supermassive black holes (SMBHs) that reside at the center of most massive galaxies.
However, there are still open questions about the role of non-interacting black holes in the evolution of galaxies. These binary star systems consist of a black hole and a star, and the black hole does not extract matter from its companion star. In a UAH press release, Dr. Chakrabari said:
“It is not yet clear how these non-interacting black holes affect the galactic dynamics of the Milky Way. If there are many of them, they could influence the formation of galaxies and their internal dynamics. We looked for objects reported to have a companion mass, but the brightness could be attributed to a single visible star, so there is good reason to think that the companion star is faint.”
To find the black hole, Dr. Chakrabarti and her team analyzed data from Gaia DR3. It contained information about about 200,000 binary stars observed by the European Space Agency’s (ESA) Gaia Observatory. The team followed up on sources of interest with reference to spectral measurements from other telescopes, including Lick Observatory’s Automatic Planet Detector, the Giant Magellan Telescope (GMT), and her WM Keck Observatory in Hawaii.
These measurements indicate that main-sequence stars are subject to strong gravitational forces. Dr. Chakrabari explained:
“The gravitational pull of black holes in visible Sun-like stars can be determined from these spectroscopic measurements, which give the radial velocity due to the Doppler shift. By analyzing the radial velocity of visible light, the star – And this visible star resembles our own Sun – We can infer how massive the black hole companion is, how long it rotates, and how eccentric its orbit is. These spectroscopic measurements independently confirm Gaia’s solution, and the binary system is thought to consist of visible stars orbiting a very massive object.”
Interacting black holes are usually easier to observe in visible light. Because they are in narrower orbits, they are attracting matter from their stellar companions. This matter forms a torus-shaped accretion disk around the black hole, accelerates to relativistic velocities (close to the speed of light), becomes highly energetic, and emits X-ray radiation.
Non-interacting black holes have wider orbits and do not form these disks, so their existence must be inferred from analyzing the motions of visible stars. Dr. Chakrabarti said:
“The vast majority of black holes in binary systems are X-ray binaries, which means they are bright in X-rays due to some interaction with the black hole, often because the black hole devours other stars. When light from another star falls well through this deep gravitational potential, we see X-rays, in this case a massive black hole, orbiting a long period of 185 days, or about half a year. is quite far away and we are not moving towards it.”
The techniques employed by Dr. Chakrabarti and her colleagues may lead to the discovery of even more non-interacting systems.
According to current estimates, our galaxy may contain one million visible stars with companions to massive black holes. This is only a small fraction of the number of stars (about 100 billion stars), but the Gaia Observatory’s precise measurements narrowed down the search. To this day, Gaia is the planet of stars, galaxies,
Further study of this ensemble will allow astronomers to learn more about this binary ensemble and black hole formation pathways. Dr. Chakrabarti summarizes:
“Although several different routes have now been proposed by theorists, non-interacting black holes around bright stars represent a very new type of population. It may take some time to understand how they form and how they form.These channels differ from the well-known ensembles of interacting and coalescing black holes. (or if similar).”
This article was originally published by Universe Today. Please read the original article.
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