| Description |
Gamma-Ray Bursts (GRBs) are so luminous that they can shine through highly
obscured galaxies, nearby and in the remote universe. GRBs enable
identification of galaxies independently of their luminosity, thus singling
out a population that is a potentially powerful probe of galaxy evolution.
Here we propose PACS and SPIRE imaging of the host galaxies of dark GRBs, GRBs
whose optical afterglow emission is weaker than expected relative to Xrays.
Recent work suggests that the main cause of the optical darkness of a GRB is
dust extinction and moderate redshift, and their hosts may be a significant
component of the GRB host galaxy (GRBH) population at redshifts > 1. Our
sample of 13 dark GRBHs has been carefully selected by requiring a prior
Spitzer detection, so that we will be ensured of detecting the far-IR emission
with Herschel. We already have collected a large amount of ancillary
multiwavelength data which will be combined with the Herschel photometry to
construct spectral energy distributions (SEDs) from the UV to the far-IR.
Fitting SEDs with a library of galaxy templates will enable us to derive
bolometric luminosities and SFRs, constrain dust mass, dust temperature, and
grain properties, as well as stellar age and mass. We will compare the dust
and stellar components of the galaxies, and analyze the GRBHs in the context
of other high-z galaxy populations. Such a program is now possible thanks to
the unique ability of Herschel to study dust emission in galaxies over a wide
range of redshifts. Ultimately our proposed study of GRBHs will open a new
window on the study of galaxy formation and evolution. |
