The maps in this animation show how the sky looks at gamma-ray energies
above 100 million electron volts (MeV) with a view centered on the north
galactic pole. The first frame shows the sky during a three-hour
interval prior to GRB 130427A. The second frame shows a three-hour
interval starting 2.5 hours before the burst, and ending 30 minutes into
the event. The Fermi team chose this interval to demonstrate how bright
the burst was relative to the rest of the gamma-ray sky. This burst was
bright enough that Fermi autonomously left its normal surveying mode to
give the LAT instrument a better view, so the three-hour exposure
following the burst does not cover the whole sky in the usual way. Credit: NASA/DOE/Fermi LAT Collaboration.
This animation shows a more detailed Fermi LAT view of GRB 130427A. The
sequence shows high-energy (100 Mev to 100 GeV) gamma rays from a
20-degree-wide region of the sky starting three minutes before the burst
to 14 hours after. Following an initial one-second spike, the LAT
emission remained relatively quiet for the next 15 seconds while Fermi's
GBM instrument showed bright, variable lower-energy emission. Then the
burst re-brightened in the LAT over the next few minutes and remained
bright for nearly half a day.
Credit: NASA/DOE/Fermi LAT Collaboration. › Larger animated image
Credit: NASA/DOE/Fermi LAT Collaboration. › Larger animated image
Swift's X-Ray Telescope took this
26.5-second exposure of GRB 130427A at 3:50 a.m. EDT on April 27, just
moments after Swift and Fermi triggered on the outburst. The image is
6.5 arcminutes across. Credit: NASA/Swift/Stefan Immler. › Larger image
The burst subsequently was detected in optical, infrared and radio
wavelengths by ground-based observatories, based on the rapid accurate
position from Swift. Astronomers quickly learned that the GRB was
located 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 outward at nearly the speed of light.
The jets bore all the way 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, astronomers usually discover a supernova at the site a week or so after the outburst.
"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.
Ground-based observatories are monitoring the location of GRB 130427A and expect to find an underlying supernova by midmonth.
The jets bore all the way 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, astronomers usually discover a supernova at the site a week or so after the outburst.
"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.
Ground-based observatories are monitoring the location of GRB 130427A and expect to find an underlying supernova by midmonth.
Related Links
› Download additional graphics from NASA Goddard's Scientific Visualization Studio
› Archive of GRB notices from the Gamma-ray Coordination Network
› "NASA's Fermi Telescope Sees Most Extreme Gamma-ray Blast Yet" (02.19.09)
› NASA's Fermi Gamma-ray Space Telescope
› NASA's Swift mission
NASA's Goddard Space Flight Center, Greenbelt, Md.
