Astronomy Now Home
Home Magazine Sky Chart Resources Store

On Sale Now!



The April 2014 issue of Astronomy Now is on sale! Order direct from our store (free 1st class post & to UK addresses). The Astronomy Now iPad/iPhone editions are now available worldwide in the iTunes store.



Top Stories



Earthshine used to test life detection method
...By imagining the Earth as an exoplanet, scientists observing our planet's reflected light on the Moon with ESO's Very Large Telescope have demonstrated a way to detect life on other worlds...
  READ MORE

Solid buckyballs discovered in space
...Astronomers using NASA’s Spitzer Space Telescope have detected a particular type of molecule, given the nickname “buckyball”, in a solid form for the first time...
  READ MORE

Steamy water-world gets the Hubble treatment
...Hubble Space Telescope observations of a 7 Earth-mass planet find an unusual water-rich world swathed in a thick, steamy atmosphere...
  READ MORE








Most distant quasar
shines brightly

DR EMILY BALDWIN
ASTRONOMY NOW
Posted: 01 July 2011


Bookmark and Share

A team of European astronomers, including UK astronomers, have discovered a bright quasar that has been beaming light since the Universe was a mere 770 million years old.

The brilliant beacon, named ULAS J1120+0641, is powered by a black hole with a mass two billion times that of the Sun. Located at a redshift – a term relating to astronomical distances – of 7.1, its light has taken 12.9 billion years to reach us. The next most distant quasar is seen at 870 million years after the big bang, or a redshift of 6.4, although gamma ray bursts have been detected at greater distances of 8.6 and 8.2 redshifts.


Artist's impression of distant quasar ULAS J1120+0641. Image: ESO/M. Kornmesser.

“We think there are only about 100 bright quasars with redshift higher than 7 over the whole sky,” says Daniel Mortlock of Imperial College London, and lead author of the paper that appears in the 30 June edition of the journal Nature. “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.”

The quasar was initially spotted using WFCAM, an infrared camera on the UK Infrared Telescope in Hawaii, and confirmed by observations made with the Liverpool Telescope, Gemini North telescope and the European Southern Observatory’s Very Large Telescope. Over 10 million sources were analysed before the quasar was discovered, but finding such a high mass black hole is difficult to explain so early in the Universe.

"The simplest models of black hole formation just can't create a two billion solar mass black hole so soon after the big bang, so its existence is something of a problem for theoretical physicists," Mortlock tells Astronomy Now, who adds that explanations for its existence require the first stars to be extremely massive or require black holes merging much more often than generally believed. "Given how hard it was to find even one bright quasar this early in the Universe's history, there are no immediate prospects for making the sort of "population census" that might reveal more about their formation mechanisms, so I think this will remain an unanswered question for some time."

The key insight the quasar has provided so far is into conditions in the early Universe, specifically to a time period known as the reionization epoch which persisted from around 150 to 800 million years after the big bang, when intense ultraviolet radiation from the first stars began breaking apart the neutral hydrogen gas that permeated the early Universe.

"The way the light from the quasar is absorbed by the hydrogen gas immediately in front of it implies that it was maybe 10 or 50 percent neutral at that time – whereas even "just" 100 million years later it was only 0.1 percent neutral," explains Mortlock. "These inferences will become more coherent as we find more such objects, but the key thing about this quasar is that it is the first bright source we've found that we're seeing in a fairly un-ionized (i.e. neutral) Universe."

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE


HOME | NEWS ARCHIVE | MAGAZINE | SOLAR SYSTEM | SKY CHART | RESOURCES | STORES | SPACEFLIGHT NOW

© 2014 Pole Star Publications Ltd.