The 26 long-duration gamma-ray bursts (GRBs) with known redshifts form a distinct cosmological set, selected differently than other cosmological probes such as quasars and galaxies. Since the progenitors are now believed to be connected with active …
We present radio observations of the afterglow of the bright gamma-ray burst GRB 980703 made between 1 day and 1 yr after the burst. These data are combined with published late-time radio measurements and existing optical, near-infrared, and X-ray …
We report on Hubble Space Telescope (HST) Wide Field Planetary Camera 2 optical and Space Telescope Imaging Spectrograph (STIS) near- ultraviolet MAMA observations and ground-based optical observations of GRB 010222, spanning 15 hr to 71 days. The …
We present early-time Keck spectroscopic observations and late-time Hubble Space Telescope (HST) imaging of GRB 000926. The HST images show a small offset between the optical transient and a bright, compact knot in the host galaxy. Combined with the …
Using the Echellete Spectrograph Imager (ESI) on the Keck II 10 m telescope we have measured the redshifts of the host galaxies of gamma-ray bursts GRB 990506 and GRB 000418, z=1.30658+/-0.00004 and 1.1181+/-0.0001, respectively. Thanks to the …
GRB 010921 was the first HETE-2 gamma-ray burst (GRB) to be localized via its afterglow emission. The low redshift of the host galaxy, z=0.451, prompted us to undertake intensive multicolor observations with the Hubble Space Telescope with the goal …
The optical afterglow of gamma-ray burst GRB 020813 was observed for 3 hr with the LRIS spectropolarimeter at the Keck I telescope, beginning 4.7 hr after the burst was detected by the HETE-2. The spectrum reveals numerous metal absorption lines that …
The various possibilities for the progenitors of gamma-ray bursts (GRBs) manifest in differing observable properties. Through deep spectroscopic and high-resolution imaging observations of some GRB hosts, I demonstrate that well-localized …
Studies of the cosmic gamma-ray bursts (GRBs) and their host galaxies are now starting to provide interesting or even unique new insights in observational cosmology. Observed GRB host galaxies have a median magnitude Råisebox-0.5ex 25 mag, and show a …
Cosmic γ-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help …