The quasar, which lives in the core of the galaxy Markarian 231 (Mrk 231), is the closest quasar to Earth and after studying years of data from the Hubble Space Telescope, a team of astronomers have realized that this particular quasar is driven by 2 black holes trapped in an orbital spiral of death.
This discovery could be critical to the study of quasars, the super-bright emissions blasting from galaxies in the distant universe. But the fact we have a quasar that’s comparatively close to our galactic neighborhood, Mrk 231 is a great laboratory to gain an insight to these enigmatic objects.
When studying the ultraviolet emissions blasting from the quasar’s accretion disk — a disk of superheated gases surrounding the central region — a deeply fascinating discovery was made. The quasar appears to be hollowed out, resembling a ring doughnut, and using dynamical models the researchers quickly realized that there must be two supermassive black holes, one more massive than the other, carving out the center.
As they orbit one another inside the quasar’s core, the smaller black hole carves out a region at the inner edge, also creating its own, smaller accretion disk. Calculations show that the pair complete one orbit every 1.2 years. The larger black hole is approximately 150 million times the mass of our sun and its smaller partner is 4 million times the mass of our sun.
“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 Youjun Lu, of the National Astronomical Observatories of China, Chinese Academy of Sciences.
As the two black holes whip around one another, energy is lost through the emission of gravitational waves. And this means that they are slowly spiraling into one another, set to collide and merge in a few hundred thousand years.
The fact there are 2 supermassive black holes occupying the quasar speaks to Mrk 231′s violent past.
Known as a “starburst” galaxy, it is a powerhouse of star formation, birthing stars 100 times the rate of our Milky Way. The tidal disruption of a smaller galaxy merging with Mrk 231 is also highlighted by long tails of young, blue stars. The galaxy is also asymmetrical in shape, showing that the billions of stars are still in the process of settling. It’s likely that the smaller black hole in the galactic core was the central black hole occupying the smaller, merging galaxy.
“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.
Read more at Discovery News
No comments:
Post a Comment