March 8, 2006

Scientists detect most distant gamma ray burst

LONDON (Reuters) - Three international teams of astronomers
said on Wednesday they have detected the most distant gamma ray
burst ever observed in the early Universe.

The cosmic explosion, a gamma ray burst (GRB) called GRB
050904, was detected by astronomers in the United States, Japan
and Italy last September using NASA's Swift satellite.

A gamma ray burst is the most distant and powerful type of
explosion known to astronomers. It can last from a few
milliseconds to several minutes.

Some are linked with a special type of surpernovae, the
explosions marking the deaths of massive stars.

"Here we describe gamma and X-ray observations of the most
distant GRB ever observed: GRB 050904," Giancarlo Cusumano, of
the National Institute for Astrophysics in Palermo, Italy, said
in a report in the journal Nature.

He added that the explosion occurred 12.8 billion years ago
when the Universe was just 890 million years old. It could
provide scientists with clues about the early Universe.

"This means that not only did stars form in this short
period of time after the Big Bang, but also that enough time
had elapsed for them to evolve and collapse into black holes,"
Cusumano added.

Black holes have a gravitation pull so strong that nothing,
not even light, can escape from them. Gamma ray bursts are
thought to be generated by the collapse of massive stars to
form black holes.

Events like gamma ray bursts are extremely bright and can
be detected very far away, or very long ago, because it can
take billions of years for light from very distant objects to
reach Earth.

"In astronomy, distance, time and the wavelength at which
observations are made are inextricably linked," said Enrico
Ramirez-Ruiz, of the Institute for Advanced Study in Princeton,
New Jersey, in a commentary in the journal.

"Light travels at a finite speed, and so takes a finite
time to get to us. Far-off objects are thus seen as they were
in the past," he added.