[Image credit: ESO/M. Kornmesser] The BBC reports on the discovery of the most distant quasar yet seen, ULAS J1120+0641. An “angry monster” 12.9 billion light-years away – a mere 770 million years after the Big Bang. Before the process of re-ionization was completed. As the BBC report notes
The light from ULAS J1120+0641 displays the characteristic signature of neutral gas, indicating that, at 770 million years after the Big Bang, the process of re-ionization had some way to go before the process was complete.
Dr Mortlock told BBC News: “This is the first time we have seen a quasar that we are sure is sitting in a significantly neutral Universe – it might be 10%, it might be 50% of the hydrogen is neutral – but all the other ones we’ve seen, even a 100 million years later, had a fraction of the neutral gas we see in our quasar. Others we’ve detected had more like 1% or 0.1% of neutral hydrogen. So we see this quasar before the epoch of re-ionization has ended.”
What is a puzzle is the scale of the black hole driving this quasar. It has a mass two billion times that of the Sun.
Its detection is one of a number lately that have indicated the presence many super-massive objects in the early cosmos. Scientists are struggling to explain how these objects could have evolved so big, so fast.
“It is safe to say that the existence of this quasar will be giving some theorists sleepless nights,” observed Chris Willott from the Canadian Astronomy Data Centre in a News and Views article in Nature.
And here’s the ESOcast video on the discovery. [Video credit: ESO]
“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.”
The distance to the quasar was determined from observations made with the FORS2 instrument on ESO’s Very Large Telescope (VLT) and instruments on the Gemini North Telescope . Because the object is comparatively bright it is possible to take a spectrum of it (which involves splitting the light from the object into its component colours). This technique allowed the astronomers to find out quite a lot about the quasar.
These observations showed that the mass of the black hole at the centre of ULAS J1120+0641 is about two billion times that of the Sun. This very high mass is hard to explain so early on after the Big Bang. Current theories for the growth of supermassive black holes predict a slow build-up in mass as the compact object pulls in matter from its surroundings.
“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.”
Indeed. Of course, the European Southern Observatory’s Very Large Telescope [VLT] array on top of Cerro Paranal in Chile’s Atacama Desert does have the most wondrous skies. [Video credit: ESO/S. Guisard (www.eso.org/~sguisard) ESO/José Francisco Salgado (josefrancisco.org)]