The Host Galaxies of Gamma-Ray Bursts I: ISM Properties of Ten Nearby
  Long-Duration GRB Hosts
  We present the first observations from a large-scale survey of nearby (z < 1)
long-duration gamma-ray burst (LGRB) host galaxies, which consist of eight
rest-frame optical spectra obtained at Keck and Magellan. Along with two host
galaxy observations from the literature, we use optical emission line
diagnostics to determine metallicities, ionization parameters, young stellar
population ages, and star formation rates. We compare the LGRB host
environments to a variety of local and intermediate-redshift galaxy
populations, as well as the newest grid of stellar population synthesis and
photoionization models generated with the Starburst99/Mappings codes. With
these comparisons we investigate whether the GRB host galaxies are consistent
with the properties of the general galaxy population, and therefore whether
they may be used as reliable tracers of star formation. We find that LGRB host
galaxies generally have low-metallicity ISM environments out to z ~ 1. The ISM
properties of our GRB hosts, including metallicity, ionization parameter, and
young stellar population age, are significantly different from the general
galaxy population, host galaxies of nearby broad-lined Type Ic supernovae, and
nearby metal-poor galaxies.
