Mystery cosmic burst has astronomers agog

From: http://www.telegraph.co.uk/earth/main.jhtml?view=DETAILS&grid=&xml=/earth/2007/09/28/sciastro128.xml

Sep 29, 2007

Astronomers are puzzling over the discovery of an extremely powerful burst of radio waves lasting for five thousandths of a second that signalled a cataclysmic event took place three billion light years away.

The energy released by this “radio burster” was equivalent to that released by our own Sun over the period of a month and is a cosmic phenomenon that has never been witnessed before, they report in the journal Science.

Although the nature of the mysterious new object is unclear, the astronomers have some ideas of what may cause such a conflagration.

“This burst appears to have originated from the distant universe and may have been produced by an exotic event,” said Duncan Lorimer, Assistant Professor of Physics at West Virginia University and the National Radio Astronomy Observatory.

Thus is might be the “last gasp” of a black hole as it finally evaporates completely.

Another idea is that it may be some of the energy released when a pair of superdense neutron stars - collapsed stars - collide and merge.

The startling discovery came when Lorimer’s student, David Narkevic, re-analysed data from observations made by the 210-foot Parkes radio telescope in Australia, searching for well-known cosmic beacons, called pulsars, which send out clock like bursts of radiation.

The survey had covered the Magellanic Clouds, a pair of small galaxies in orbit around our own Milky Way Galaxy. Some 200,000 light-years from Earth, the Magellanic Clouds are prominent features in the Southern sky.

Ironically, the new discovery is not part of these galaxies but much more distant.

“It was a bit of luck that the survey included some observations of the sky surrounding the clouds,” Narkevic said. "It was from those “flanking” observations that the mysterious radio burst appeared.”

From the way the signal had spread, the astronomers have calculated that it likely originated about three billion light-years from Earth.

Matthew Bailes of Swinburne University in Australia, said: “This burst represents an entirely new astronomical phenomenon.”

The astronomers estimate on the basis of their results that hundreds of similar events should occur over the sky each day but they are missed because few radio surveys have the necessary sensitivity to detect them.