Keck Telescope Helps Detect First Gamma-Ray Bursts from 'Swift' Satellite
MAUNA KEA (February 14, 2005) Afterglow emission from two gamma-ray bursts detected by the NASA-led Swift mission were discovered at the W. M. Keck Observatory using the Keck I telescope on Mauna Kea. The location of two additional bursts were located using the Las Campanas Observatory in Chile and the 200-inch Hale telescope on Palomar Mountain. A team led by Carnegie-Princeton and Hubble fellow Edo Berger has been able to find and study burst afterglows thanks to the performance of NASA's new Swift satellite and rapid response by ground-based telescopes in both the southern and northern hemispheres.
"I'm thrilled," said Berger. "We've shown we can chase the Swift bursts at a moment's notice, even right before Christmas! This is a great sign of exciting advances down the road." The discoveries herald a new era in the study of gamma-ray bursts, hundreds of which are expected to be discovered and scrutinized in the next several years.
Gamma-ray bursts are the most powerful explosions in the universe, producing more energy in a few seconds than hundreds of billions of stars, yet fading away in a matter of hours or weeks. Researchers believe these explosions could mark the birth of black holes, or perhaps a cosmic collision between two neutron stars.
The Swift spacecraft found the first of the four bursts on December 23, 2004 in the constellation Puppis. Carnegie astronomers used telescopes at the Las Campanas Observatory in Chile to locate the visual afterglow within several hours. This was the first gamma-ray burst detected solely by the Swift satellite to be pinpointed with sufficient accuracy to study the emission. The next three bursts came in quick succession on January 17th, 24th and 26th. Observations of the last two bursts were made with the Near Infrared Camera (NIRC) on the 10-meter Keck I telescope at Mauna Kea, Hawai`i. The last burst was discovered right at dawn of a gamma-ray burst just four hours old!
“The last object was fairly faint, and in this case it was very important to have the light collecting power of the giant Keck telescope,” added Berger. “The localizations from Swift are of such a high quality that for the first time we can really start to use narrow-field instruments like NIRC to study the afterglow emission.”
Because Swift allows a response to new gamma-ray bursts within minutes, astronomers plan to use the intense light from gamma-ray bursts as the brightest known cosmic "flashlights." They will use the bright visual afterglows to trace the formation of the first galaxies, only a few hundred million years after the Big Bang, and the composition of the gas that permeates the universe. "This is much like using a flashlight to study the contents of a dark room," said Berger. "But because the flashlight is on for only a few hours, we have to act quickly."
The Swift mission is the most sensitive gamma-ray burst satellite and the first to have X-ray and optical telescopes on-board, allowing it to relay very accurate and rapid positions to astronomers on the ground. Launched November 2004, the satellite is a collaboration between NASA's Goddard Space Flight Center, Penn State University, Leicester University and the Mullard Space Science Laboratory (both in England), and the Osservatorio Astronomico di Brera in Italy.
"Swift's rapid response is opening a new window on the universe. I can't wait to see what we catch," remarked Neil Gehrels of Goddard Space Flight Center, principal investigator for Swift.
In the next few years the Swift satellite will find several hundred gamma-ray bursts. Follow-up observations on-board Swift and using telescopes on the ground will move astronomers a few steps closer to answering some of the most fundamental puzzles in astronomy, such as the birth of black holes, the first stars, and the first galaxies.
The team that identified and studied the afterglows of the first Swift bursts also includes Mario Hamuy, Wojtek Krzeminski, Wendy Freedman, and Eric Persson from Carnegie Observatories, Shri Kulkarni, Derek Fox, Alicia Soderberg, and Brad Cenko from Caltech, Dale Frail from the National Radio Astronomy Observatory, Paul Price from the University of Hawai'i, Eric Murphy from Yale University, and Swift team members David Burrows, John Nousek, and Joanne Hill from Penn State University, Scott Barthelmy from Goddard Space Flight Center, and Alberto Moretti from Osservatorio Astronomico di Brera."
The Carnegie Observatories is part of the Carnegie Institution (www.CarnegieInstitution.org), which has been a pioneering force in basic scientific research since 1902. It is a private, nonprofit organization with six research departments throughout the United States.
The W. M. Keck Observatory (www.keckobservatory.org) is run by the California Association for Research in Astronomy (CARA), a nonprofit scientific partnership among Caltech, the University of California, and NASA.
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Image credit: Spectrum and NASA E/PO, Sonoma State University, Aurore Simonnet
Image credit: Carnegie Observatories/W. M. Keck Observatory/Edo Berger