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Saturday, 19 February, 2000, 17:11 GMT
Most distant quasar in Universe found

MDO Newly-discovered, distant quasar (red point in centre)


By BBC News Online science editor Dr David Whitehouse

A newly discovered object deep in the constellation Cetus the Whale is one of the most distant objects ever found in our Universe.

A team of astronomers found it after many nights of long-exposure imaging using the 200-inch Hale Telescope at Mt Palomar Observatory in California and the 157-inch Mayall Telescope at Kitt Peak, Arizona.

A final analysis of the quasar's light was then completed at the Keck Observatory in Hawaii.

"As soon as we saw the spectrum, we knew we had something special," said Dr. Daniel Stern of Nasa's Jet Propulsion Laboratory. "Quasars can look very much like stars, but a spectral analysis of a quasar's light reveals its true character. This quasar told us that it was 'An Ancient' -- one of the Universe's first structures."

Quasars are ultra-luminous bodies that were more common when the Universe was young. On the cosmic scale, they are small, being packed into a volume roughly equal to our Solar System.

Black holes

Despite their size, they radiate an astonishing amount of energy - up to 10,000 times that of our own Milky Way galaxy.

Because of this vast outpouring of energy, astronomers believe that they are fuelled by super-massive black holes that eject enormous amounts of energy as they consume surrounding matter.

A quasar's "redshift" measures how fast the object is moving away from us as the Universe expands, and is an indicator of its distance.

Spec Spectrum: Record redshift

With a record redshift of 5.5, light travelling from Stern's quasar has journeyed about 13 billion years to get here. That means the quasar existed at a time when the Universe was less than 8% of its current age.

"The odds against us finding a quasar at a redshift of 5.5 were fairly large, especially when you consider how small a portion of the sky we were observing. Until just a few years ago, no one had discovered an object that came close to a redshift of 5.0," said Dr Stern.

Cosmic evolution

High-redshift quasars are very important for understanding one of the biggest mysteries confronting scientists: how the Universe went from the smooth uniformity of its youth to the clumpy, galaxy-strewn formations we observe today.

Analysing the spectrum of the new quasar will be very useful for seeing how the Universe has evolved.

As the quasar's light makes its journey across the Universe towards us, any matter that lies in its path absorbs its light. Scientists have learned that clouds of neutral hydrogen absorb more than half of a quasar's light at high redshift (in the early Universe).

This finding is central to understanding when and how super-massive black holes, quasars, and other structures condensed from large, high-density clouds of hydrogen soon after the Big Bang. The new quasar, designated RD J030117+002025, will also shed light on how matter was distributed at earlier stages of cosmic history.

"Finding a quasar at this distance is like turning on a flashlight at the edge of the Universe," said Stern. "Because quasars are more luminous than distant galaxies at the same redshift, they act as the brightest flashlights, allowing us to study everything that has ever developed between us and the quasar."

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See also:
20 Jan 00 |  Sci/Tech
Giant telescope's close-up on quasars
10 Dec 98 |  Sci/Tech
The most distant object ever seen
26 May 99 |  Sci/Tech
Universe is 12 billion years old

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