This Thursday, 20:10 GMT, the astronomy twitter journal club goes festive with a discussion on GRB 101225A – the unusual gamma-ray burst which was detected by the SWIFT satellite on Christmas Day last year.
Artist's impression (with festive enhancement) of a supernova explosion and resulting gamma-ray burst. Photo credit: NASA with apologies
The majority of gamma ray bursts are thought to be massive stellar explosions in distant galaxies, but the Christmas event didn’t fit this picture; the initial burst of gamma rays lasted for an unusually long time and, despite the efforts of powerful optical telescopes, no convincing candidate for the host galaxy could be found.
Nearly a year on from the initial observation two groups of astronomers have come up with two different, but equally plausible, explanations for the odd GRB 101225A. The first team suggest that it was caused by something small, like a comet, breaking apart and then falling into a neutron star within our own Milky Way. The alternative theory, put forward by the second team, also involves a neutron star, but in this case it’s merging with a young red giant star in another galaxy.
The two related scientific papers were published in the same edition of Nature:
The unusual γ-ray burst GRB 101225A from a helium star/neutron star merger at redshift 0.33
The unusual gamma-ray burst GRB 101225A explained as a minor body falling onto a neutron star
However, if you don’t have access to Nature they’re both on the arXiv: here and here.
Unless the host of this gamma ray burst is found, and its distance measured, there’s no easy way to choose between these two options. Hopefully deeper optical data with, for example, a telescope like Hubble will provide the answers and settle this debate.
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