There are an estimated 100 million stellar-mass black holes in the Milky Way
Washington:
The closest known black hole to Earth has been found by astronomers using the International Gemini Observatory, operated by NSF’s NOIRLab.
It has been confirmed for the first time that a black hole of inactive stellar mass exists in the Milky Way. With only 1600 light years between it and Earth, it is a fascinating subject to study in order to advance our knowledge of the evolution of binary systems.
The most extreme things in the universe are black holes. All giant galaxies probably have supermassive versions of these dense, elusive objects at their centres.
There are an estimated 100 million stellar-mass black holes in the Milky Way alone, which are considerably more common and 5 to 100 times more massive than the Sun. In contrast to dormant black holes, which do not glow strongly in X-rays as they consume matter from a nearby companion star, only a small number have been confirmed so far, and nearly all of them. they both “work”.
The closest black hole to Earth has been named Gaia BH1 by astronomers using the Gemini North telescope on the island of Hawaii, one of the twin telescopes of the International Gemini Observatory, operated by NSF’s NOIRLab .
It is three times closer to Earth than the previous record, a pair of X-rays in the constellation Monoceros. This dormant black hole is 10 times larger than the Sun and is located about 1600 light-years from the constellation Ophiuchus. Subtle studies of the motion of the black hole’s partner, a star similar to the Sun orbiting the black hole at the same distance as Earth orbits the Sun, has enabled the new discovery.
Kareem El-Badry, an astrophysicist at the Center for Astrophysics, explains: “Take the Solar System, place a black hole in the Sun’s position and the Sun in the Earth’s position, and you’ll have get this system,” said Kareem El-Badry, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian and the Max Planck Institute for Astronomy, and lead author of the paper describing the discovery.
“Although there have been many claimed discoveries of systems like this, almost all of these were subsequently disproved. This is the first unequivocal discovery of a Sun-like star. in a wide orbit around a stellar-mass black hole in our Galaxy.”
The few stellar-mass black holes that have been found have been revealed by their energetic interactions with a companion star, despite the fact that there may be millions of them moving in the sky. Milky Way Galaxy. Superheated material from a nearby star spirals toward the black hole, where it produces intense X-rays and jet jets of matter. When a black hole is inactive (i.e. not actively feeding), it simply blends into its surroundings.
“I’ve been searching for dormant black holes for the past four years using a variety of data sets and methods,” said El-Badry. “My previous efforts – as well as those of others – have produced a series of binary systems masquerading as black holes, but this is the first time the search has worked.”
Data from the European Space Agency’s Gaia spacecraft was initially examined by researchers to determine the system’s potential presence of a black hole. Gaia recorded very small deviations in the star’s velocity brought on by an invisible giant object.
El-Badry and his team used the Gemini Multi-Object Spectrograph on Gemini North to study the system in more detail. This instrument accurately determines the orbital period of the companion star by measuring the companion star’s velocity as it orbits the black hole. The team was able to identify the central object as a black hole 10 times as massive as our Sun thanks to follow-up Gemini observations, which was essential in introducing restrictions on the orbital velocity. direction and thus the mass of the two components in the binary system.
“Our subsequent observations of Gemini confirmed beyond reasonable doubt that the binary system contains an ordinary star and at least one inactive black hole,” explains El-Badry. explain. “We could not find any plausible astrophysics scenario that would explain the observed orbit of the system that did not involve at least one black hole.”
Since they only have a small window into which to make follow-up observations, the team relies not only on Gemini North’s excellent observations, but also on Gemini’s ability to provide data at short notice. .
“When we had the first indications that the system contained a black hole, we had only a week before the two objects were at their closest distances in their orbits. The measurements at this point are what’s going on. needed to give an accurate mass estimate in a binary system”. El-Badry said. “Gemini’s ability to deliver observations over a short period of time is critical to the success of the project. If we miss that narrow timescale, we’ll have to wait another year. ”
The unique configuration of the Gaia BH1 system is difficult to explain using astronomers’ current concepts of the evolution of binary systems. The progenitor star, which would later evolve into the newly discovered black hole, would have a mass at least 20 times that of the Sun.
It will have a short lifespan of a few million years. If both stars were to form at the same time, the massive star would rapidly develop into a supergiant, inflating and swallowing the second before it had a chance to develop into a star in the galaxy. Main sequence, like our Sun, burns hydrogen.
It’s not clear how the solar-mass star was able to survive the wave, ending up as a seemingly normal star, as observations of black hole binaries show. Permissive theoretical models predict that the sun-mass star should end up in a much tighter orbit than is actually observed.
This could indicate that there are important gaps in our understanding of how black holes form and grow in binary systems, and also suggest the existence of a population of sleeping black holes. unexplored in binary systems.
“Interestingly, this system does not readily respond to standard binary evolutionary models,” concludes El-Badry. “It raises many questions about how this binary system was formed, as well as how many dormant black holes are out there.”
(Except for the title, this story has not been edited by NDTV staff and is published from an aggregated feed.)
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