An article published in “Nature” describes the research conducted by an international team led by Jochen Greiner of the Max-Planck-Institut für extraterrestrische Physik, Garching, Germany who studied a gamma-ray burst (GRB) detected on December 9, 2011 by NASA’s Swift satellite and called GRB 111209A. It was an exceptional phenomenon because it lasted more than three hours when gamma-ray bursts typically last from a few seconds to a few minutes. It was the first case of GRB associated with a supernova, called SN 2011kl, which produced a magnetar, a neutron star with an incredibly strong magnetic field.
Long or very long gamma-ray bursts are a rarity so the one observed on December 9, 2011 and called GRB 111209A was a great event in the field of astrophysics. It’s estimated that a gamma-ray burst of that kind happens once every 10,000 to 100,000 supernovae so the one associated with this event must be somehow special.
The supernova SN 2011kl was discovered through observations conducted to study the consequences of this gamma-ray burst with the GROND (Gamma-Ray Burst Optical / Near-Infrared Detector) instrument on the MPG/ESO 2.2-meter telescope at La Silla observatory and with the X-shooter instrument on the VLT (Very Large Telescope) at Paranal Observatory. Both are in Chile and are ESO’s observatories.
It was the first time a connection between a supernova and a gamma-ray burst was found. Previously, connections between normal supernovae and short duration gamma-ray bursts were found. Consequently, this supernova became the subject of special studies to understand the origin of such a long gamma-ray burst.
The observations revealed that the supernova SN 2011kl was very bright but the results were unexpected. The researchers carried out complex analyzes of the radiation emitted by the supernova expecting to find a black hole in formation. Instead the measurements carried out led to only one possible explanation, which is the birth of a magnetar.
Depending on the mass that remains after a supernova, its collapse can lead to the birth of a neutron star or of a black hole. In the case of supernova SN 2011kl, a mass that could be more or less than the Sun collapsed into a sphere that has a radius around 10 kilometers (a little more than 6 miles). The neutron star that has formed is of the type called a magnetar, which has the most powerful magnetic field known in the universe.
The connection between gamma-ray bursts, bright supernovae and magnetars found through this research is unexpected. Some of these connections were theorized in recent years but these observations put together more elements than expected. We’re talking about really extreme events and objects as magnetars’ magnetic fields have immense power and that gamma-ray bursts can wreak havoc even on planets light years away.
