Cosmic gamma-ray bursts produce more energy in the blink of an eye, than the Sun will release in its entire lifetime. These short-lived explosions appear to be the death throes of massive stars, and, a number of researchers believe, mark the birth of black holes. Testing these ideas has been difficult, however, because the bursts fade so quickly and rapid action is required. Now a team of Carnegie and Caltech astronomers, led by Carnegie-Princeton and Hubble fellow Edo Berger, has made crucial strides toward answering these cosmic quandaries. The team was able to discover and study burst afterglows thanks to the exquisite performance of NASA's new Swift satellite and rapid follow-up with telescopes in both the southern and northern hemispheres.
"I'm thrilled," said Berger. "We've shown that 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.
The Swift satellite detected the first of the four bursts on December 23, 2004, in the constellation Puppis, and Carnegie astronomers used telescopes at the Las Campanas Observatory in Chile to pinpoint the visual afterglow within several hours. This was the first burst detected solely by the new Swift satellite to be pinpointed with sufficient accuracy to study the remains. The next three bursts came in quick succession between January 17 and 26 and were immediately pinpointed by a team of Carnegie and Caltech astronomers using the Palomar Mountain 200-inch Hale telescope in California and the Keck Observatory 10-meter telescopes in Hawaii.
"The Las Campanas telescopes are ideal for their flexibility to follow up targets like gamma-ray bursts, which quickly fade out of view," said Carnegie Observatories director Wendy Freedman. "This is a wonderful example of science that comes from the synergy between telescopes on the ground and in space, and between public and private observatories".
Because Swift allows a response to new gamma-ray bursts within minutes, astronomers hope to use the intense light from gamma-ray bursts as cosmic "flashlights." They plan to 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".
"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.
Swift, launched on November 20, 2004, is the most sensitive gamma-ray burst satellite to date, 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. 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.
In the next few years the Swift satellite is expected to find several hundred gamma-ray bursts. Follow-up observations on-board Swift and using telescopes on the ground should move us 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-in addition to Berger, Freedman and Gehrels-includes Mario Hamuy, Wojtek Krzeminski, 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 Hawaii, 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.
Source: Carnegie Institution
Posted By: Brooke