The center of the Milky Way may hide tens of thousands of black holes
There is not just one black hole in the center of our galaxy. A team of astrophysicists from Columbia University has found dozens of smaller black holes clustered around the supermassive black hole Sagittarius A* at the center of the Milky Way. The findings suggest that there may be many more of them there, up to 20,000.
For more than two decades, researchers have unsuccessfully searched for evidence of theów confirming the theory that thousands of smaller black holes surround supermassive black holes at the center of large galaxies. This concept mósees that there should be a local increase in the number of stellar-mass black holes near supermassive black holes in the centers of galaxies.
– There are few known black holes in the entire galaxy 100,000 light years wide. There should be 10,000 to 20,000 such sitesóin a region just six light-years wide. However, no one has been able to find them – said Columbia University astrophysicist Chuck Hailey, head of theówny author of the study, które appeared in the latest issue of „Nature”.
Hailey added that there have been many fruitless searches for black holes wokół the closest supermassive black hole to Earth, Sagittarius A* (Sgr A*), located at the center of the Milky Way.
– Anything you want to learn about how supermassive black holes interact with small black holes, you can find out by studying this decomposition. The Milky Way is really the only galaxy in której we can study howób supermassive black holes interact with small ones, because most simply cannot see their interactions in other galaxies. In a sense, it is the only laboratory thatórym we can study this phenomenon – admitted Hailey.
To find black holes, compositeóThe researchers had to think outside the box. Black holes are difficult to locate because they do not emit any radiation themselves – in fact, they absorb all detectable radiation, although theoretically they emit Hawking radiation, but we are unable to detect it. But that doesn’t mean they can’t be found in other waysób.
When the black hole "wakes up" and consumes matter, creates this detectable X-ray radiation. The most active black holes are those in conjunction with a star in the sub systemójnym. They absorb matter from the star, which sometimes produces bright flashes of X-rays. This is the so-called. X-ray sub systemsójne. Usually one of the membersóin such a pair is a black hole or neutron star.
Previous searches for black holes in the center of our galaxy have focused on these X-ray flashes. But this method has a drawback. – This is an obvious wayób to look for black holes, but the galactic center is so far from Earth that these outbursts are visible once every 100 to 1,000 years – explained Hailey.
Instead of waiting for the next flare of the compositeół used a different approach. Sifting through data collected by the Chandra X-ray Observatory over the past 12 years, researchers have searched for a weaker but more stable signature of X-rays produced by X-ray sub systemsójne. When a neutron star is paired in such a system, a sudden increase and then decrease in radiative emissions is often observed. This occurs much more frequently than flashes emitted by X-ray black hole systems.
– If X-ray black hole systems routinely emitted strong flashes like neutron star systems, it would be easy to locate them, but this is not the case, so we had to come up with another way toób of their search. When black holes merge with a low-mass star, „marriage” it emits flashes of X-rays, które are weaker, but spójne and detectable. If we found black holes connected to low-mass stars and knew what fraction of black holes connect to such stars, we could infer the population of isolated black holes – Hailey pointed out.
In data from the Chandra Observatory, researchers found 12 signatures matching the X-ray systemów subóible particles paired with low-mass black holes. All at a distance of three light years from Sgr A*. They then analyzed the properties and spatial distribution of these events. In the end, they concluded that there must be between 300 and 500 systems near the center of the Milky Wayóin a subójnych low-mass black holes and about 10,000 lone black holes.
Sgr A* is surrounded by a halo of gas and dust, providing the perfect environment for the birth of massive stars. Discoveries of astronomerów support the thesis that wokół Sgr A* has given birth to many massive stars, whichóre lived, died and collapsed into black holes. It supports the róalso support the thesis that smaller black holes of stellar mass have moved toward the galactic center from other parts of the galaxy.
– Our discovery could greatly accelerate the study of gravitational waves, since knowing the number of black holes at the center of a typical galaxy can helpóc in better predicting how many gravitational events might be associated with them – assessed Hailey.