Earlier on this year, an extraordinarily long Gamma Ray Burst sparked a flurry of excitement in the scientific community, prompting several groups to attempt to explain the unusual event. Now, an international team of astronomers, including scientists from Penn State and the University of Leicester, has come up with a new, elegantly simple explanation for these enigmatic events. The work is due to be presented next week in St. Petersburg, Russia.
As the name suggests, Gamma-Ray Bursts (GRBs) are fleeting, intense blasts of gamma-ray light, which is the most energetic form of light. These spectacular explosions are some of the most powerful events in the universe, shining around a million trillion times brighter than the Sun. On average, these violent events occur around once a day, usually lasting from a few milliseconds to several minutes. It was therefore particularly unusual for scientists to observe the energy from one flooding toward Earth for more than five hours.
This rare event, which was named GRB 130925A, is a member of a newly recognized class of GRBs called ultra-long bursts. The explosion was observed using the Swift satellite’s X-ray Telescope and the US/Russian satellite Konus-Wind.
The discovery of these unusual events prompted scientists to wonder whether current theories could adequately explain them, but nonetheless several papers were released on GRB 130925A. Now, according to a new study, the most likely explanation is much simpler than first anticipated.
After examining the observations from Swift and Konus-Wind, the researchers found that these ultra-long gamma-ray bursts are actually standard explosions, but what sets them apart are the conditions in which they arise. According to Penn State professor of astronomy David Burrows, all that is required is for the event to occur within a low-density region located behind a dust cloud when viewed from Earth.
“One reason that these results are satisfying is that scientists generally prefer to find the simplest explanations for mysterious phenomena,” said Burrows.
[Via Penn State]