black holes they are among the most amazing and mysterious objects in the known Universe. These gravitational giants form when massive stars undergo gravitational collapse at the end of their lifetimes, shedding their outer layers in a massive explosion (a supernova).
Meanwhile, the stellar remnant becomes so dense that the curvature of space-time becomes infinite in its vicinity and its gravity so intense that nothing (not even light) can escape its surface. This makes them impossible to observe using conventional optical telescopes that study objects in visible light.
As a result, astronomers often search for black holes at non-visible wavelengths or by observing their effect on nearby objects.
After consulting the Gaia Data Version 3 (DR3), a team of astronomers led by the University of Alabama Huntsville (UAH) recently observed a black hole in our cosmic backyard. As they describe in their study, this monster black hole it has about twelve times the mass of our Sun and is about 1,550 light-years from Earth.
Due to its mass and relative proximity, this black hole presents opportunities for astrophysicists.
The study was led by Dr. Sukanya Chakrabarti, Pei-Ling Chan Chair at the UAH Department of Physics. She was joined by astronomers from the Carnegie Institution for Science Observatories, the Rochester Institute of Technology, the Carl Sagan Center of the SETI Institute, UC Santa Cruz, UC Berkeley, the University of Notre Dame, Wisconsin-Milwaukee, Hawaii and Yale.
The article describing their findings recently appeared online and is being reviewed by the astrophysical journal.
Black holes are of particular interest to astronomers because they offer opportunities to study the laws of physics under the most extreme conditions. In some cases, such as the supermassive black holes (SMBHs) that reside at the center of most massive galaxies, they also play a vital role in galaxy formation and evolution.
However, there are still unanswered questions about the role of non-interacting black holes in galactic evolution. These binary systems consist of a black hole and a star, where the black hole does not extract material from the stellar companion. Said Dr. Chakrabari in a UAH Press release:
“It is not yet clear how these non-interacting black holes affect the galactic dynamics in the Milky Way. If they are numerous, it is possible that they affect the formation of our galaxy and its internal dynamics. We looked for objects that were reported to have large masses. companions but whose brightness could be attributed to a single visible star. So you have good reason to think the companion is dim.”
To find the black hole, Dr. Chakrabarti and his team analyzed data from Gaia DR3, which included information on almost 200,000 binary stars observed by the European Space Agency (ESA). Gaia Observatory. The team tracked sources of interest by consulting spectrographic measurements from other telescopes, including the Lick Observatory’s Automated Planet Finder, the Giant Magellan Telescope (GMT), and the WM Keck Observatory in Hawaii.
These measurements showed a main sequence star subject to a powerful gravitational pull. as Dr. Chakrabari explained:
“The attraction of the black hole on the visible Sun-like star can be determined from these spectroscopic measurements, which give us a line-of-sight velocity due to a Doppler shift. By analyzing the line-of-sight velocities of the visible star, and this visible star is similar to our own Sun, we can infer how massive the black hole companion is, as well as the period of rotation and how eccentric the orbit is, that this binary system is composed of a visible star that is orbiting a very massive object.”
The interacting black holes are often easier to observe in visible light because they are in tighter orbits and are pulling material from their stellar companions. This material forms a torus-shaped accretion disk around the black hole that accelerates to relativistic speeds (close to the speed of light), becoming highly energetic and emitting X-ray radiation.
Because non-interacting black holes have wider orbits and do not form these disks, their presence must be inferred from analysis of the visible star’s motions. Said Dr Chakrabarti:
“Most black holes in binary systems are in X-ray binaries; in other words, they are bright in X-rays due to some interaction with the black hole, often due to the black hole gobbling up the other star. As matter from the other star falls into this deep well of gravitational potential, we can see X-rays… It’s quite far from the visible star and not moving toward it.”
The techniques employed by Dr. Chakrabarti and his colleagues could lead to the discovery of many more non-interacting systems.
Based on current estimates, there could be a million stars visible in our galaxy that have companion massive black holes. While this represents a small fraction of its stellar population (~100 billion stars), precise measurements from the Gaia Observatory have narrowed that search. To date, Gaia has obtained data on the positions and proper motions of more than a billion astronomical objects, including stars, galaxies,
Further study of this population will allow astronomers to learn more about this population of binary systems and the pathway of black hole formation. as Dr. Chakrabarti summarized:
“Currently, theorists have proposed several different pathways, but non-interacting black holes around luminous stars are a very new type of population. So it will likely take us some time to understand their demographics, how they form, and how these channels are different from, or similar to, the better-known population of interacting and merging black holes.”
This article was originally published by universe today. read the original article.
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