By Mark Brown, Wired UK

Meet ULAS J1120+0641, the most distant quasar ever found. A team of European astronomers have used a number of telescopes, data from The European UKIRT Infrared Deep Sky Survey (UKIDSS) and five years of searching to find it.

A quasar is a very bright, very distant galaxy that is juiced up by a supermassive black hole at its centre. The black hole in the middle of ULAS J11 has a mass two billion times that of our Sun, and the overall galaxy is the brightest object in the early Universe.

We see now it as it was just 770 million years after the Big Bang, during the prehistoric Universe’s reionization era. This was when the intense ultraviolet radiation of early stars ripped apart hydrogen atoms into protons and electrons, making the Universe more transparent to ultraviolet light.

Stellar objects from this era are so stretched out by the expansion of the Universe that they fall mostly in the infrared part of the spectrum. But while they hide in visible-light surveys, they can be spotted by dedicated infrared telescopes, like the UKIRT telescope in Hilo, Hawaii.

The team of astronomers spent half a decade hunting through millions of objects in the UKIDSS database to find quasars. “We were looking for a quasar with redshift higher than 6.5,” said Bram Venemans, one of the authors of the study. “Finding one that is this far away, at a redshift higher than 7, was an exciting surprise.”

Its discovery gives astronomers new information on the first few hundred million years history of the universe. The high mass of the supermassive black hole at such an early age could rewrite theories that these objects build up very slowly over time.

“We think there are only about 100 bright quasars with redshift higher than 7 over the whole sky,” concludes Daniel Mortlock, the leading 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.”

Image: An artist’s impression of ULAS J1120+0641, a distant quasar powered by a black hole that’s 2 billion times more massive than of the Sun. (ESO/M. Kornmesser) [High-resolution version available]

Source: Wired.co.uk

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