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D. Q. Lamb, T. Q. Donaghy, C. Graziani (University of Chicago)
One third of all HETE-2--localized bursts are X-Ray Flashes (XRFs), a class of events first identified by Heise in which the fluence in the 2-30 keV energy band exceeds that in the 30-400 keV energy band. I summarize recent HETE-2 and other results on the properties of XRFs. These results show that the properties of XRFs, X-ray-rich gamma-ray bursts (GRBs), and GRBs form a continuum, and thus provide evidence that all three kinds of bursts are the same phenomenon. I review the theoretical models that have been proposed to explain XRFs, including variable-opening angle and universal jet models, and relativistic beaming models. I show that XRFs provide unique insights into the structure of GRB jets, the rate of GRBs, and the nature of Type Ib/Ic core collapse supernovae. I also show that they are of vital importance to using GRBs as "standard candles" for cosmology. I describe how a scientific partnership between HETE-2 and Swift can greatly advance our understanding of XRFs. This research was supported in part by NASA Contract NASW-4690 and NASA Grant NAG5-10759
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.