22
May 2003
Gamma-ray bursters: Magnetic power sources
The RHESSI γ-ray observatory satellite was launched in February 2002 tasked with tracking the radiation released by solar flares in X-rays and γ-rays. A serendipitous observation by RHESSI has now produced an important result in another field of γ-ray astronomy, contributing evidence on one of the burning questions in astronomy today, the nature of the central engine that powers γ-ray bursts (GRBs). RHESSI's detectors are trained on a broad sweep of sky, to get a good view of the solar emissions, so the chances of picking up a γ-ray burst at cosmological distances are not great. But the early emissions from GRB021206 were detected, and the high degree of polarization reveals some of the properties of the radiation source. The massive explosions at the centre of GRB021206 seem to be driven by magnetic forces, probably created by the extraction of rotational energy from either a neutron star or a black hole.
Polarization of the prompt g-ray
emission from the g-ray burst of 6 December
2002
WAYNE COBURN & STEVEN E. BOGGS
Nature
423, 415–417 (2003); doi:10.1038/nature01612
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Astronomy: New direction for g-rays
ELI WAXMAN
The origin of energetic g-ray
bursts is still unknown. But the detection of polarization of the g-rays
provides fresh insight into the mechanism driving these powerful explosions.
Nature 423, 388–389 (2003); doi:10.1038/423388a
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