By Nadia Drake
The unusually bright and long-lived gamma-ray burst that appeared on December 25, 2010, is an enigmatic holiday gift that isn’t quite unwrapped yet.
After nearly a year, scientists trying to catch the culprit behind the perplexing explosion have arrived at two completely different answers, both presented in the Dec. 1 Nature. One theory involves a small object, such as an asteroid or comet, passing too close to a neutron star and going out in a gamma blaze of glory. The other theory suggests that a gnarly stellar merger — followed by a dim supernova — delivered the bizarre Christmas burst.
Detected by NASA’s Swift satellite, the event lasted much longer than typical gamma-ray bursts, which hurl intense pulses of high-energy gamma rays into space. Weird X-rays and unexpected heat emissions characterized the afterglow, which didn’t fade normally, either. “I have a list of oddball events that we’ve seen with Swift, and this probably tops the list,” says astrophysicist Neil Gehrels of NASA’s Goddard Space Flight Center in Greenbelt, Md., who leads the team managing the Swift satellite. “What I find interesting and amusing is that these are completely different models to explain the same data.”