The Center of Our Galaxy is Swarming With Black Holes, Scientists Say

  • The Center of Our Galaxy is Swarming With Black Holes, Scientists Say

The Center of Our Galaxy is Swarming With Black Holes, Scientists Say

New research has found that it's not alone. "The galactic center is a unusual place".

But since black holes are black, with nothing - including light - able to escape their mighty grasp, how does one exactly go about finding them?

Black holes are generally "pretty impossible" to see, according to the physicist. But you can see evidence of a black hole's meal.

Previous attempts to detect this population of black holes have looked for the bright bursts of X-rays that are sometimes emitted by black hole binaries. It can be particularly tricky to distinguish between binary systems involving quiescent (minimally accreting) black holes and millisecond pulsars.

Using a similar system where the 100-watt bulbs represent the 12 bright black holes, the team deduced that between 300 to 500 fainter black hole binaries were spinning around in the galactic centre. "These objects also provide a unique laboratory for learning about how big black holes interact with little ones, because we can't readily study these processes in other, more distant galaxies". So, too, do astrophysical exotica such as neutron stars and white dwarfs-the remnants left by normal stars when they die.

"They're devilishly hard to find", Chuck Hailey, lead author of the paper and astrophysicist with Columbia University told CBC News.

There is already a supermassive black hole at the center of the Milky Way now scientists have found many smaller ones. Black holes consuming a dying star emit low-energy X-rays compared to other stars or objects, so they were able to isolate them omitting other, high-energy X-rays. Furthermore, all black holes in the nearby vicinity of Sagittarius A* are held close by its massive gravitational pull. They form after the spectacular death of a massive star - about 10 times that of our own sun - a supernova explosion that can outshine the star's host galaxy. So there's still a lot of empty space and gas amid all those black holes.

Astronomers poring over old x-ray observations have found signs of a dozen black holes in the inner circle of the Milky Way.

As gravity takes over and eventually wins, it forms a singularity, a single point in space where gravity is so strong that no object - not even light - can escape its grasp once it crosses its boundary.

The newly confirmed black holes are about 10 times the mass of our sun, as opposed to the central supermassive black hole, which has the mass of 4 million suns. "All the information astrophysicists need is right there, at the center of our galaxy".

We really think we basically understand how things are happening at the centre of the galaxy. As they suck up all the surrounding gas, the material spirals around it like a whirlpool, creating an accretion disk.

Instead, the researchers looked for slow-burn signals that would also indicate the presence of smaller black holes, in order to spot all of the signals that otherwise can't be observed. "Some of them were formed comparatively recently". Black holes are tricky to locate, since they themselves don't give off any radiation - in fact, they absorb all detectable radiation (theoretically they emit Hawking radiation, but we can't detect that).

Morris calls the work "exciting" but notes that due to the very low total numbers of photons used in the analysis, of the dozen putative black holes some might actually merely be statistical flukes produced by coincidentally timed emissions from other sources. "It is going to significantly advance gravitational wave research because knowing the number of black holes in the center of a typical galaxy can help in better predicting how many gravitational wave events may be associated with them".