1999/09/01 by D. Q. Lamb, F. J. Castander, Francisco J. Castander +2 · 3 citations
Physics and Astronomy · #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1051/aas:1999318
Proceedings of Gamma-Ray Bursts in the Afterglow Era, Nov. 1998, Rome, F. Frontera & L. Piro eds., A&A Suppl. Ser., in press
arxiv created 1999/09/01 · openalex publication_date 1999/09/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We find that the local galactic extinction towards the field of gamma-ray burst GRB 970228 is , which implies a substantial dimming and change in the spectral slope of the intrinsic GRB 970228 afterglow. We measure a color for the extended source coincident with the afterglow. Taking into account our measurement of the extinction toward this field, this color implies that the extended source is most likely a galaxy undergoing star formation, in agreement with our earlier conclusion (Castander & Lamb 1998). In a separate analysis, we find that the inferred intrinsic spectrum of the GRB 980329 afterglow is consistent with the predictions of the simplest relativistic fireball model. We also find that the intrinsic spectrum of the afterglow is extincted both by dust (source frame 1 mag), and that the shape of the extinction curve is typical of young star-forming regions like the Orion Nebula but is not typical of older star-forming or starburst regions. The ≈ 2 mag drop between the R and the I bands can be explained by the far-ultraviolet non-linear component of the extinction curve if , and by the 2175 Å bump if ; other redshifts are not consistent with the observational data, given our general model.