Astronomers Discover Most Distant Quasar
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Artist’s impression showing how quasar ULAS J1120+0641 may have looked 770 million years after the Big Bang.
Image Credit: ESO/M. Kornmesser
In a letter appearing in this week’s Nature, researchers Mortlock, Warren, et al, present their findings on quasar ULAS J1120+0641.
Based on their findings, the light from the quasar took nearly thirteen billion years to reach us, presenting a view of the quasar from less than 800 million years after the Big Bang.
“This quasar is a vital probe of the early Universe. It is a very rare object that will help us to understand how supermassive black holes grew a few hundred million years after the Big Bang,” says Stephen Warren, leader of the research team.
What make quasars interesting to astronomers is that they are extremely bright, yet distant galaxies, believed to possess “supermassive” black holes in their galactic centers. The brightness of quasars make them ideal “beacons” to help understand the era in which the first stars and galaxies were formed.
There have been other, more distant objects found in our universe, but the second most-distant quasar was seen as it was almost 900 million years after the Big Bang. Objects this distant are seen in infra-red due to their light being stretched, or “red shifted” (ULAS J1120+0641 is at redshift 7.1) by the expansion of the Universe. To search for objects like ULAS J1120+0641, the astronomers searched through the Infrared Deep Sky Survey database, based on data acquired from the United Kingdom Infrared Telescope in Hawaii.
“It took us five years to find this object,” explains Bram Venemans, one of the authors of the study. “We were looking for a quasar with redshift higher than 6.5. Finding one that is this far away, at a redshift higher than 7, was an exciting surprise. By peering deep into the reionisation era, this quasar provides a unique opportunity to explore a 100-million-year window in the history of the cosmos that was previously out of reach.”
Determining the distance to the quasar, the team used data from the FORS2 instrument on ESO’s Very Large Telescope (VLT) and instruments on the Gemini North Telescope. The brightness of the quasar allowed the team to analyze the spectrum of the emitted light, allowing them to learn much more about the quasar. The astronomers estimate the central supermassive black hole in ULAS J1120+0641 is nearly two billion times the mass of the Sun. The extremely high mass is difficult to explain for an object formed so soon after the Big Bang, as it’s theorized supermassive black holes build their mass slowly through galactic mergers and matter accretion.
“We think there are only about 100 bright quasars with redshift higher than 7 over the whole sky,” adds Daniel Mortlock, lead author of the paper. “Finding this object required a painstaking search, but it was worth the effort to be able to unravel some of the mysteries of the early Universe.“
If you’d like to read the scientific paper on this discovery, you can download a copy at: http://www.eso.org/public/archives/releases/sciencepapers/eso1122/eso1122.pdf
Source:AAAS News Release , Nature
Ray Sanders is a Sci-Fi geek, astronomer and blogger. Currently researching variable stars at Arizona State University, he writes for Universe Today, The Planetary Society blog, and his own blog, Dear Astronomer
2012-12-04 08:06:18
Source: http://www.dearastronomer.com/2011/06/30/astronomers-discover-most-distant-quasar/
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