Astronomers detect record breaking gamma ray burst
Sen—A record-setting gamma ray burst (GRB) from a dying star in a distant galaxy has produced the highest-energy light ever detected from such an event.
On Saturday April 27, NASA's Fermi space telescope detected an eruption of high-energy light in the constellation Leo. The gamma ray burst, designated GRB 130427A, was also detected by NASA's Swift telescope.
Fermi's Large Area Telescope (LAT) recorded one gamma ray with an energy of at least 94 billion electron volts (GeV), 35 billion times the energy of visible light, and about three times greater than the LAT's previous record. The GeV emission from the burst lasted for hours, and it remained detectable by the LAT for the better part of a day, setting a new record for the longest gamma-ray emission from a GRB.
Swift's X-Ray Telescope took this 0.1-second exposure of GRB 130427A just moments after Swift and Fermi triggered on the outburst. The image is 6.5 arcminutes across. Image credit: NASA/Swift/Stefan Immler
"We have waited a long time for a gamma-ray burst this shockingly, eye-wateringly bright," said Julie McEnery, project scientist for the Fermi Gamma-ray Space Telescope at NASA's Goddard Space Flight Center. "The GRB lasted so long that a record number of telescopes on the ground were able to catch it while space-based observations were still ongoing."
The burst was detected in optical, infrared and radio wavelengths by ground-based observatories, based on the rapid accurate position from Swift. Astronomers quickly located the GRB to about 3.6 billion light-years away, which for these events is relatively close.
Gamma-ray bursts are the universe's most luminous explosions. Astronomers think most occur when massive stars run out of nuclear fuel and collapse under their own weight. As the core collapses into a black hole, jets of material shoot out at nearly the speed of light. The jets bore through the collapsing star and continue into space, where they interact with gas previously shed by the star and generate bright afterglows that fade with time. If the GRB is near enough, a supernova is usually discovered at the site a week or so after the outburst. Ground-based observatories are monitoring the location of GRB 130427A and expect to find an underlying supernova by midmonth.
"This GRB is in the closest 5 percent of bursts, so the big push now is to find an emerging supernova, which accompanies nearly all long GRBs at this distance," said Goddard's Neil Gehrels, principal investigator for Swift.