Nasa searches for birth of black holes

By JAMES BURLEIGH

A new space observatory was rocketing into space yesterday preparing to scan the universe for the most violent celestial explosions since the Big Bang.

The $250 million Nasa probe, called Swift, will detect and analyse gamma ray bursts, which astronomers believe represent the birth screams of black holes.

The bursts last just a few seconds and appear out of nowhere.

The observatory, which was launched from Florida's Cape Canaveral on Saturday, carries three telescopes that work together.

One, the Burst Alert telescope, was built by the American space agency's Goddard research centre; the x-ray telescope was built by Penn State University, the University of Leicester and the Osservatorio Astronomico di Brera; and the ultraviolet optical telescope was made by Penn State and University College London's Mullard Space Science Laboratory.

Swift should begin its hunt for gamma ray bursts by January.

Astronomers believe the collapse or collision of massive stars produces black holes - so dense not even light can escape - and the resulting gravitational energy sends gamma rays shooting out across time and space.

Neil Gehrels, Nasa's principal scientist, said: "We think that, perhaps, bursts are the birth cries of black holes and we're seeing these throughout the universe."

A single gamma ray burst released more energy than the sun would emit in its lifetime, Mr Gehrels said.

So far, astronomers have managed to identify only a few dozen gamma ray bursts, as close as a few million light years away and as far as 12 billion light years.

During its two-year mission, Swift should zero in on two gamma ray bursts a week as far away as 15 billion light years, representing the first generation of stars.

The spacecraft will scan one-sixth of the sky at a time and so see one-sixth of all gamma ray bursts.

"We expect to detect and analyse over 100 gamma-ray bursts a year," Dr Gehrels said. "Swift will lead to a windfall of discovery of these most powerful explosions in the universe."

The Hubble Space telescope, by contrast, can take up to two days to swivel into a viewing position.

After chasing gamma ray bursts for a year or two, Swift will expand its repertoire to other rapidly occurring cosmic events.

Gamma-ray bursts were first observed during the Cold War, when Western researchers thought that they might be the product of Soviet nuclear tests on other planets or the Moon.

- INDEPENDENT