The Surroundings of Gamma-Ray Bursts: Constraints on Progenitors

Abstract

The association of a supernova with a gamma-ray burst (GRB 030329) implies a massive star progenitor, which is expected to have an environment formed by pre-burst stellar winds. Although some sources are consistent with the expected wind environment, many are not, being better fit by a uniform density environment. One possibility is that this is a shocked wind, close to the burst because of a high interstellar pressure and a low mass loss density. Alternatively, there is more than one kind of burst progenitor, some of which interact directly with the interstellar medium. Another proposed environment is a pulsar wind bubble that has expanded inside a supernova, which requires that the supernova precede the burst.

10 pages, review, IAU Colloq. 192, Apr. 22-26, 2003, Supernovae: 10 Years of 1993J, eds. J.M. Marcaide, K.W. Weiler, Springer Verlag