It’s been clear for almost a decade that the predominant class of gamma-ray bursts—the so-called classic or long-duration GRBs—are at cosmological distances. The accepted picture is that a classic GRB spews out about 1051 ergs (1044 joules) in a back-to-back pair of narrow beams of gamma radiation that typically lasts tens of seconds. Less clear is the underlying mechanism responsible for such spectacular energy release.
One much-considered mechanism has been the cataclysmic merger of a neutron star with a “compact” binary partner—a black hole or another neutron star. But that model seems to yield subsecond bursts that are too short for classic GRBs. Nor does it explain why so many GRBs are associated with star-forming regions.
More popular nowadays is the “collapsar” model introduced by Stan Woosley (University of California, Santa Barbara) in 1993 (see Physics Today, July 2002, page 18). Woosley proposed that a small...
