NASA's Swift detects possible birth of black hole

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Friday, January 21, 2005

Swift satellite

On Jan. 17, the NASA-led Swift satellite mission detected and imaged its first gamma-ray burst, one of the most powerful explosions to occur in the universe.

The burst was in the midst of exploding as Swift, designed to autonomously repoint itself, turned and focused in less than 200 seconds on the event. The satellite was fast enough to capture an image with its X-Ray Telescope (XRT), while gamma rays were still being detected with the Burst Alert Telescope (BAT).

"This is the first time an X-ray telescope has imaged a gamma-ray burst while it was bursting," said Dr. Neil Gehrels, Swift's principal investigator at NASA's Goddard Space Flight Center, Greenbelt, MD. "Most bursts are gone in about ten seconds, and few last upwards of a minute. Previous X-ray images have captured the burst afterglow, not the burst itself."

"This is the one that didn't get away," said Prof. John Nousek, Swift's mission operations director at Penn State University, in State College, PA. "And this is what Swift was built to do: to detect these fleeting gamma-ray bursts and focus its telescopes on them autonomously within about a minute. The most exciting thing is this mission is just revving up."

Swift has three main instruments. The BAT detects bursts and initiates the autonomous slewing to bring the XRT and the Ultraviolet/Optical Telescope (UVOT) within focus of the burst. In December, the BAT started detecting bursts, including a remarkable triple detection on Dec. 19. Today's announcement marks the first BAT detection autonomously followed by XRT detection, demonstrating the satellite is swiftly slewing as planned. The UVOT is still being tested, and it was not collecting data when the burst was detected. Scientists expect Swift to be fully operational by Feb. 1.

"We are frantically analyzing the XRT data to understand the X-ray emission seen during the initial explosion and the very early afterglow," said Dr. David Burrows, the XRT lead at Penn State. "This is a whole new ballgame. No one has ever imaged X-rays during the transition of a gamma-ray burst from the brilliant flash to the fading embers."

The origin of gamma-ray bursts remains a mystery. At least some appear to originate in massive star explosions. Others might be the result of merging black holes or neutron stars. Any of these scenarios likely will result in the formation of a new black hole.

The Swift satellite's two-year mission will be to:

  • Determine the origin of gamma-ray bursts.
  • Classify gamma-ray bursts and search for new types.
  • Determine how the explosion develops.
  • Use gamma-ray bursts to study the early universe.
  • Perform the first sensitive hard X-ray survey of the sky.

Swift, still in its checkout phase, is an international collaboration launched on Nov. 20, 2004. It is a NASA mission in partnership with the Italian Space Agency and the Particle Physics and Astronomy Research Council, United Kingdom.

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