By Ron Cowen
Astronomers have discovered direct evidence that gamma-ray bursts, the most energetic events in the universe, are linked to supernovas, the explosive death of massive stars.
On March 29, NASA’s High-Energy Transient Explorer satellite detected one of the closest gamma-ray bursts on record. For half a minute, the burst outshone the gamma rays from all the rest of the universe.
Observations of the burst’s afterglow began a half-day later. In early April, astronomers saw signs of a supernova explosion superimposed on the afterglow. Those signs included an upswing in the fading light’s intensity as well as the presence of heavy elements, such as iron, that can be forged only in supernovas.
Astronomers have for several years suspected a link between gamma-ray bursts, theorized to be the birth cries of black holes, and supernovas, whose aftermaths can leave behind either a neutron star or a black hole (SN: 7/10/99, p. 28).
“This is the first direct, spectroscopic confirmation that a subset of . . . gamma-ray bursts originate from supernovas,” Tom Matheson of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and his colleagues assert in an April 9 circular of the International Astronomical Union.
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