Published: Thu, April 05, 2018
Science | By

The Milky Way Galaxy Is Growing Faster Than the Speed of Sound

The Milky Way Galaxy Is Growing Faster Than the Speed of Sound

Astronomers now believe that most galaxies have massive black holes at their center to help keep everything together.

Black holes, which are vast amounts of matter asked into small areas, are typically ten times larger than our own sun but packed into an area roughly the diameter of NY city. In addition, "the galactic center is very crowded so it is hard to differentiate systems in which a black hole is present from other more prosaic X-ray sources such as white dwarfs". They also calculate that there are likely thousands of them there.

Artistic depiction of a black hole "devouring" a star.

Hailey noted that despite the theory that thousands of black holes should be close to each other, relatively few of the celestial bodies have actually been discovered in the Milky Way.

He said: "Isolated black holes just don't do much that would lend themselves to easy detection". Researchers saw that it would be challenging to observe the Milky Way growing since the solar system sits in one of its arms.

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.

The illustration above shows the supermassive black hole Sagittarius A, located at the center of the Milky Way Galaxy, surrounded by a cloud of dust and gas, within which are 12 smaller black holes, and a closeup of one of the systems. The orbiting pair is called a black hole binary. "The galactic center is a odd place". But mostly the center of the galaxy is the ideal "hot house" for black hole formation, with lots of dust and gas.

The black hole at the centre of the Milky Way galaxy Sagittarius A
The black hole at the centre of the Milky Way galaxy Sagittarius A

An artist's impression of a black hole binary.

"If we could find black holes that are coupled with low-mass stars and we know what fraction of black holes will mate with low-mass stars, we could scientifically infer the population of isolated black holes out there". Some of the matter is blasted back out in hot, powerful jets. Martínez-Lombilla and her colleagues at the Instituto de Astrofísica de Canarias in Tenerife, Spain have set out to establish whether other spiral galaxies similar to the Milky Way really are getting bigger, and if so what this means for our own galaxy.

Objects pulled into the inescapable gravitation pull of black holes, will speed up, gain heat and produce increased amounts of X-ray radiation into space, which in turn our instruments can pick up.

Extrapolating from their distribution, he and his team calculated that there is probably hundreds of black hole binaries keeping Sagittarius A* company - and potentially more than 10,000 solo black holes.

A group of astrophysicists analysed X-rays emitted from the heart of the galaxy to hunt for black holes using data taken from NASA's Chandra X-ray Observatory.

This, Professor Hailey said, "is just the tip of the iceberg of all the black holes there".

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