The most energetic gamma-ray burst ever detected was announced this week by the team at the Fermi Gamma-Ray Space Telescope. The gamma-ray burst (or GRB) event was triggered on Saturday 27 April 2013, and so the GRB has the name GRB 130427A. The Fermi Large Area Telescope (LAT) recorded energies up to 94 GeV, almost 3 times higher the energy of the previous LAT record of GRBs. The GeV emission lasted for several hours and remained detectable by LAT for most of the day. As well as the most energetic, GRB 130427A also set the record for the longest gamma-ray emission from a GRB measured to date.
When Fermi triggered the GRB event, the Swift satellite quickly determined its position towards the constellation Leo. With the position tied down, follow-up observations were immediately made by ground-based optical, infrared and radio telescopes, including finding an optical counter-part in the Catalina Real-time Transient Survey. The GRB is now know to have originated in a distant galaxy about 3.6 billion light years away.
GRBs are brief but very intense bursts of gamma radiation. There are two types of GRBs defined by the length of their burst. Long bursts (longer than two seconds) are thought to be associated with supernova explosions that result when massive stars run out of nuclear fuel and undergo sudden collapse, and short bursts (shorter than two second) are thought to originate from the merger of two compact objects such as neutron stars. Both types are GRBs are likely signal the birth of a black hole. In the case of GRB 130427A, the long-period burst likely resulted from core collapse of a massive star.
For more information, see
- NASA’s Fermi, Swift See ‘Shockingly Bright’ Burst, NASA Features
The “Wow” blast, HEASARC pic of the week
- Gamma-ray Coordinates Network (GNC) circulars: GCN Circular #14448, GCN Circular #14450, GCN Circular #14471 and GCN Circular #14508
- An untriggered optical detection of GRB 130427A, The Astronomers Telegram
- GCN (Gamma-ray Coordinates Network) Report Archive (keep an eye on this for details!)
- Fermi Gamma-ray Space Telescope, NASA site
- Fermi Gamma-ray Space Telescope, Goddard site
- Swift Gamma-ray Burst Mission