Does 2 merging black holes necessarily make a quasar? - Astronomy gsusigmanu.org - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from gsusigmanu.org Daily Mail and Mail on Sunday newspapers.
Generically, such an object is called an active galaxy
. If one of those beams happens to be pointed at Earth, we can see lots of light from across almost the entire electromagnetic spectrum, from radio waves to X-rays.
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Artwork depicting binary quasars, two actively galaxies orbiting one another. Credit: NASA/ESA/Hubble/ESO/M. Kornmesser, adapted by Phil Plait
We know that there are extremely massive black holes out there which may have grown to such enormous size when two big galaxies merge. The black holes fall toward each other, eventually orbiting each other and then, after billions of years, they can merge together into one bigger black hole. This implies we should find binary supermassive black holes, or at least two that are close together (say, within a few thousand light years of each other). However very few are seen, mainly because they re hard to discover.
A pair of quasar pairs in the ancient Universe give us a look at the future of our own galaxy. They could help explain how galaxies and black holes evolve.
An artist’s impression of two ancient galaxies, each hosting a supermassive black hole, in the process of merging. In a few tens of millions of years, the two quasars will marge, leaving a single, even more massive black hole in their wake. Image: NASA, ESA, and J. Olmsted (STScI)
Astronomers have spotted two close pairs of quasars in the process of merging as their host galaxies crash together in a slow-motion collision 10 billion years ago. The quasars in both pairs are separated by about 10,000 light years, closer than any two quasars yet found at such an early point in the evolution of the universe.
Quasars are the extremely luminous state that some supermassive black hole can achieve. If these enormous cosmic objects are undergoing a feeding frenzy, they start throwing some of the material out with such energy that they can outshine their host galaxies. Galaxy collision can provide the fuel to start a quasar and, on rare occasions, quasars periods will begin in the supermassive black holes of both colliding galaxies. Now, astronomers have snapped two pairs of quasars – and they are the closest double quasars ever seen in the distant universe.
The findings, reported in Nature Astronomy, suggest that the black holes in each pair are just several thousand light-years apart and that the galaxies are well underway their merger, getting close to being a single object. The light from the quasars has traveled for at least 10 billion years, with the furthest one coming from 11,5 billion years ago. That pair has a projected separation of 11,400 light-years.