March 9, 2006, University Park, PA--In this week's issue of Nature, scientists at Penn State and their U.S. and European colleagues discuss how the gamma-ray burst, detected on Sept. 4 by telescopes aboard NASA's Swift satellite, was the result of a massive star collapsing into a black hole.
It came from an era soon after stars and galaxies first formed, about 500 million to 1 billion years after the Big Bang. The universe is now 13.7 billion years old, so the September burst serves as a probe to study early conditions.
"This was a massive star that lived fast and died young," said David Burrows, senior scientist and professor of astronomy and astrophysics at Penn State, a co-author on one of the three reports about this explosion published this week in Nature. "This star was probably quite different from the kind we see today, the type that only could have existed in the early universe."
Upon detecting the burst, named GRB 050904 after the date it was spotted, Swift, which is operated by Penn State, provided coordinates so that other satellites and ground-based telescopes could observe it. Bursts typically last only 10 seconds, but the afterglow will linger for a few days.
GRB 050904 originated 13 billion light years from Earth, which means it occurred 13 billion years ago. Scientists have detected only a few objects more than 12 billion light years away, so the burst is extremely important in understanding the universe beyond the reach of the largest telescopes.
Only one quasar has been discovered at a greater distance. Yet, whereas quasars are supermassive black holes containing the mass of billions of stars, this burst comes from a single star. The detection of GRB 050904 confirms that massive stars mingled with the oldest quasars. It also confirms that even more distant star explosions -- perhaps from the first stars, theorists say -- can be studied through a combination of observations with Swift and other world-class telescopes.
"We designed Swift to look for faint bursts coming from the edge of the universe," said Neil Gehrels of NASA Goddard Space Flight Center in Greenbelt, Md., Swift's principal investigator. "Now we've got one and it's fascinating. For the first time we can learn about individual stars from near the beginning of time. There are surely many more out there."
Swift was launched in November 2004 and was fully operational by January 2005. It carries three main instruments: the Burst Alert Telescope, the X-ray Telescope and the Ultraviolet/Optical Telescope.
Swift's gamma-ray detector, the Burst Alert Telescope, provides the rapid initial location and was built primarily by the NASA Goddard Space Flight Center in Greenbelt and Los Alamos National Laboratory and constructed at GSFC.
Swift's X-Ray Telescope and UV/Optical Telescope were developed and built by international teams led by Penn State and drew heavily on each institution's experience with previous space missions. The X-ray Telescope resulted from Penn State's collaboration with the University of Leicester in England and the Brera Astronomical Observatory in Italy.
The Ultraviolet/Optical Telescope resulted from Penn State's collaboration with the Mullard Space Science Laboratory of the University College-London.
These three telescopes give Swift the ability to do almost immediate follow-up observations of most gamma-ray bursts because Swift can rotate so quickly to point toward the source of the gamma-ray signal.