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.” Finding one that is this far away, at a redshift higher than 7, was an exciting surprise. “We were looking for a quasar with redshift higher than 6.5. “It took us five years to find this object,” explains Bram Venemans, one of the authors of the study. The team of astronomers hunted through millions of objects in the UKIDSS database to find those that could be the long-sought distant quasars, and eventually struck gold. The European UKIRT Infrared Deep Sky Survey (UKIDSS) which uses the UK's dedicated infrared telescope in Hawaii was designed to solve this problem. Similar objects further away cannot be found in visible-light surveys because their light, stretched by the expansion of the Universe, falls mostly in the infrared part of the spectrum by the time it gets to Earth. The next most-distant quasar is seen as it was 870 million years after the Big Bang (redshift 6.4).
Amongst objects bright enough to be studied in detail, this is the most distant by a large margin. It took 12.9 billion years for its light to reach us.Īlthough more distant objects have been confirmed (such as a gamma-ray burst at redshift 8.2, eso0917, and a galaxy at redshift 8.6, eso1041), the newly discovered quasar is hundreds of times brighter than these. The quasar that has just been found, named ULAS J1120+0641, is seen as it was only 770 million years after the Big Bang (redshift 7.1, ). The newly discovered quasar is so far away that its light probes the last part of the reionisation era. Their brilliance makes them powerful beacons that may help to probe the era when the first stars and galaxies were forming.
Quasars are very bright, distant galaxies that are believed to be powered by supermassive black holes at their centres. 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, the study’s team leader. “This quasar is a vital probe of the early Universe. The results will appear in the 30 June 2011 issue of the journal Nature. This brilliant beacon, powered by a black hole with a mass two billion times that of the Sun, is by far the brightest object yet discovered in the early Universe. A team of European astronomers has used ESO’s Very Large Telescope and a host of other telescopes to discover and study the most distant quasar found to date.
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