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Researchers find brightest galaxy in the known universe
David Taft for redOrbit.com – Your Universe Online
NASA’s Wide-field Infrared Survey Explorer has found the brightest galaxy in the known universe. This galaxy, fondly named WISE J224607.57-052635.0, emits over 300 trillion times more light than our sun.
This new discovery is part of a category of celestial objects termed “extremely luminous infrared galaxies”, or ELIRGs.
The main source of the galaxy’s energy output is a supermassive black hole at its center. When a large black hole pulls in surrounding matter, the gravity and friction of the matter orbiting the edge of the event horizon superheats the material, causing it to release energy in the form of light. This kind of black hole, which compresses the matter around it into a luminous disk, is called a quasar.
Although quasars are not rare, the example at the center of WISE J224607.57-052635.0 is unique because of its age relative to the mass of its black hole.
Although the images we see of this quasar and its galaxy are over 12.5 billion years old, it was already sustaining a gravitational pull of billions of times the mass of our sun, even when the universe was only about one tenth of its now 13.8 billion year age.
How can this black hole exist?
Three theories about the relative age and size of the black hole at the center of WISE J224607.57-052635.0 have been presented in a report by NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, which was released in the May 22 issue of The Astrophysical Journal.
The first possibility is that the ‘seeds,’ or miniature black holes that attract matter to grow to become full sized, may start out much larger than previously thought. The first signs of black hole seeds were gathered by the same WISE telescope that discovered this superluminous galaxy.
The second and third theories state that this black hole may have somehow surpassed the Eddington limit, which is reached when the release of energy from a quasar’s matter consumption begins to push away potential matter that the black hole would intake. This has been thought to act as a kind of check for the rate of expansion a black hole can sustain, but researchers now believe that there may be exceptions.
It appears that black holes may be able to exceed the Eddington limit by spinning at a slower rate, and therefore lessening the velocity of the stellar wind they release. This slower rotation allows more matter to remain within the gravitational range of the black hole, thus allowing it to ingest matter and expand at a higher rate.
Much is still unknown
JPL scientists are also considering the idea that there may be a way for a black hole to intake matter at such a rate that its gravity overpowers the repulsive effects of its energy release, which could also enable it to overcome the Eddington limit.
Much still remains unknown regarding the mass, age, and gravitational properties of the black holes that sit at the center of these ELIRGs. One of the main reasons that galaxies like these haven’t been discovered until now is the fact that many ELIRGs emit most of their energy as infrared light.
The WISE telescope has reportedly found 20 more of these galaxies since it completed its mission to capture images of the entire sky in a twofold scan during 2010. In September 2013, WISE was reactivated and renamed NEOWISE. It is currently in service on a new mission to help NASA locate and identify potentially dangerous near-Earth objects.
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Source: http://www.redorbit.com/news/space/1113396485/researchers-find-brightest-galaxy-in-known-universe-052415/
