Study finds millions of black holes in Milky Way

A study conducted by a group of scientists at the University of California (UCI) has revealed that there may be as many as 100 million black holes in the Milky Way galaxy.

The UCI researchers launched the celestial census after the first ever detection of gravitational waves in the year 2015. It was basically launched to investigate the ‘weirdness of the Laser Interferometer Gravitational-Wave Observatory (LIGO) discovery.’ As per the discovery, the gravitational waves were created by the collision of two 30-solar-mass black holes.

Key highlights

• The celestial census began more than a year and a half ago, shortly after the news that the Laser LIGO had detected ripples in the space-time continuum created by the distant collision of two black holes, each the size of 30 suns.

• Scientists assume that most stellar-remnant black holes will be about the same mass as the Sun.

• The new study was an attempt to interpret the gravitational wave detections through the lens of what is known about galaxy formation and to form a framework for understanding future occurrences.

• The number of black holes of a given mass per galaxy usually depends on the size of the galaxy. It is because larger galaxies have many metal-rich stars, and smaller dwarf galaxies are dominated by big stars of low metallicity. Stars that contain a lot of heavier elements shed a lot of that mass over their lives. When it comes time for one to end it all in a supernova, there is not as much matter left to collapse in on itself, resulting in a lower-mass black hole. Big stars with low metal content do not shed as much of their mass over time. Therefore, when one of them dies, almost all of its mass will wind up in the black hole.

• The researchers then determined the number of black holes based on what they know about star formation in different kinds of galaxies.