Washington: A team of astrophysicists and astronomers, led by Dr Youjun Lu of the National Astronomical Observatories of China, has found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.
The discovery of two black holes - one larger one and a second, smaller one - is evidence of a binary black hole and suggests that supermassive black holes assemble their masses through violent mergers.
Scientists looked at Hubble archival observations of ultraviolet radiation emitted from the center of Mrk 231, then applied a model developed by Dr Lu to the spectrum of the galaxy. Following which, they were able to predict the existence of the binary black holes in it.
“We are extremely excited about this finding because it not only shows the existence of a close binary black hole in Mrk 231, but also paves a new way to systematically search binary black holes via the nature of their ultraviolet light emission,” said Dr Lu.
“The structure of our universe, such as those giant galaxies and clusters of galaxies, grows by merging smaller systems into larger ones, and binary black holes are natural consequences of these mergers of galaxies,” added co-investigator Xinyu Dai of the University of Oklahoma.
Markarian 231, also called UGC 8058, is a Type-1 Seyfert galaxy that was discovered in 1969 as part of a search of galaxies with strong ultraviolet radiation. It is located about 600 million light years away from Earth.
So over time, the two black holes discovered by Dai and Lu in Mrk 231 will collide and merge to form a quasar with a supermassive black hole. A quasar is an active galaxy with an illuminated center, which is short lived compared to the age of the universe.
The results were published in the August 14, 2015, edition of The Astrophysical Journal.
(Source: University of Oklahoma)