Free Access
Issue
Astron. Astrophys. Suppl. Ser.
Volume 138, Number 3, September 1999
Gamma-Ray Bursts in the Afterglow Era Contents Rome, November 3-6, 1998
Page(s) 479 - 480
DOI https://doi.org/10.1051/aas:1999318
Published online 15 September 1999
DOI: 10.1051/aas:1999318



Astron. Astrophys. Suppl. Ser. 138, 479-480

GRB 970228 and GRB 980329 and the nature of their host galaxies

D.Q. Lamb - F.J. Castander - D.E. Reichart

Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, U.S.A.

Received January 21; accepted June 30, 1999

Abstract:

We find that the local galactic extinction towards the field of gamma-ray burst GRB 970228 is AV=1.09+0.10-0.20, which implies a substantial dimming and change in the spectral slope of the intrinsic GRB 970228 afterglow. We measure a color $(V_{606}-I_{814})_{\rm ST} =
-0.18^{+0.51}_{-0.61}$ 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 ([#!CL98!#, 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 $A_V \mathrel{\mathchoice {\vcenter{\offinterlineskip\halign{\hfil
$\displaystyl...
 ...{\offinterlineskip\halign{\hfil$\scriptscriptstyle ... 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 $\approx$ 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 $3 \mathrel{\mathchoice {\vcenter{\offinterlineskip\halign{\hfil
$\displaystyle ... , and by the 2175 Å bump if $z \approx 2$; other redshifts are not consistent with the observational data, given our general model.

Key words: gamma-rays: bursts

SIMBAD Objects

Copyright The European Southern Observatory (ESO)

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.