THE locations of titanic cosmic explosions called short gamma-ray bursts have been traced for the first time.
These radiation flashes last less than a second and are extremely difficult to study. But with agile space telescopes such as NASA鈥檚 Swift, which can swivel within a minute towards a gamma-ray burst (GRB), astronomers can now study the afterglow of such flashes. In July, an international team used a combination of space and ground-based telescopes to detect and study the X-ray afterglow of two short GRBs. One originated about 10,000 light years from the centre of a star-forming galaxy that is about 1.8 billion light years from Earth. The other came from within an old galaxy about 2.8 billion light years away.
The locations of the bursts rules out flare-ups in highly magnetic neutron stars, called magnetars. Theory limits how distant a magnetar-based GRB we can detect, and these bursts happened 10 times farther away than this limit.
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Instead, the observations favour the 鈥渃oalescence model鈥�, which says that short GRBs occur when two neutron stars, or a neutron star and a black hole, merge. 鈥淭he coalescence model is the model to beat,鈥� says Dale Frail, of the National Radio Astronomy Observatory in Socorro, New Mexico.
