Black holes are among the most fascinating and mysterious objects in the known universe. These gravitational forces are created when massive stars undergo gravitational collapse at the end of their lives and shed their outer layers in a massive explosion (supernova).
Meanwhile, the remnants of stars become so dense that the curvature of space-time is unbounded locally and gravity is so strong that nothing (not even light) can escape its surface. This makes the objects invisible using conventional optical telescopes that study visible light.
As a result, astronomers typically search for black holes at invisible wavelengths or by observing their effects on matter around them.
A team of astronomers led by Huntsville, Alabama (UAH) recently observed a black hole in our cosmic backyard after consulting Gaia Data Release 3 (DR3). According to their research, this monster black hole has a mass twelve times that of our Sun and is located 1,550 light-years from Earth.
Due to its mass and relative proximity, this black hole offers opportunities for astronomers.
The research was led by Dr. Sukanya Chakrabarty, Pei-Ling Chan Endowed Chair of UAH’s Department of Physics. She is joined by astronomers from the Carnegie Institution for Science, 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.
A paper detailing their findings recently appeared online and is under review. Astrophysical Journal.
Black holes are of special interest to astronomers, as they provide opportunities to study the laws of physics in extremely difficult conditions. In some cases, such as supermassive black holes (SMBH) at the center of supermassive galaxies, they also play a crucial role in galaxy formation and evolution.
However, there are still unresolved questions regarding the role of non-interacting black holes in galactic evolution. These binary systems consist of a black hole and a star, and the black hole does not attract material from the star. Dr. Chakrabari said in a UAH press release:
“It is not yet clear how these non-interacting black holes affect the galactic dynamics of the Milky Way. If there are more of them, they could affect the formation of our galaxy and its internal dynamics. We looked for material that has been reported to have many companions. But the brightness is only visible from one star, so the companion may be dark.” You have good reason to think so.
To find the black hole, Dr. Chakrabarti and his team analyzed the Gaia DR3 data, which contains data on nearly 200,000 binary stars observed by the European Space Agency’s (ESA) Gaia Observatory. The team tracked sources of interest by looking at other telescopes, such as the Lick Observatory Automated Planet Finder, the Giant Magellan Telescope (GMT) and the WM Keck Observatory in Hawaii.
These measurements revealed a main sequence star subject to strong gravitational pull. As Dr Chakrabari explains:
“The drag of a black hole on a visible Sun-like star can be determined from these spectroscopic measurements, which give us the optical speed due to the Doppler shift. By analyzing the optical speed of the star – and this visible star is the same as our own Sun – how massive the black hole companion is, as well as We can imagine how complicated its rotation period and orbit are. These spectroscopic measurements independently confirmed the solution of Gaia. This binary system is composed of a star orbiting a very massive object.
Interacting black holes are easy to see with visible light because they orbit narrowly and pull material away from their stellar partners. This material forms an accelerated torus-shaped accretion disk around the black hole, which accelerates to relativistic velocities (close to the speed of light), with high energy and emits X-rays.
Since non-interacting black holes have wider orbits and do not form these disks, their presence must be inferred from analysis of the observed stellar motion. Dr. Chakrabarty:
“Most black holes in binary systems are in X-ray binaries – in other words, they are bright in X-rays because of some interaction with the black hole, usually because the black hole has absorbed another star. From the other star, it falls into this deep gravitational hole, and we can see the X-rays. In this case, we are looking at a monster black hole, but it has a long-term orbit of 185 days, or about half a year. It is very far from the visible star and does not make any progress.
The techniques employed by Dr. Chakrabarti and her colleagues may lead to the discovery of many more non-interacting systems.
At current estimates, there may be a million visible stars in our galaxy that have massive black hole companions. While this represents a small fraction of its stellar population (~100 billion stars), accurate measurements from the Gaia Observatory have narrowed the search. To date, Gaia has acquired data on the position and exact motion of more than 1 billion stellar bodies—stars, galaxies,
Further studies of this population will allow astronomers to learn more about this population of binary systems and how black holes form. Dr. Chakrabarti concluded:
“There are currently various channels proposed by theorists, but black holes that do not interact with each other around luminous stars are a very new type of population. So it may take us some time to understand their demographics and how they form and how they form. These channels – or if they are similar – are very popular. They are different in interacting with humans and integrating black holes.
This article was originally published by Universe Today. Read the original article.
