It is now accepted that long-duration γ-ray bursts (GRBs) are produced during the collapse of a massive star$^1,2$. The standard `collapsar' model$^3$ predicts that a broad-lined and luminous type Ic core-collapse supernova accompanies every …
Even with the renaissance in gamma-ray burst (GRB) research fostered by the Swift satellite, few bursts have both contemporaneous observations at long wavelengths and exquisite observations at later times across the electromagnetic spectrum. We …
We investigate properties of the interstellar medium (ISM) in galaxies hosting long-duration γ-ray bursts (GRBs) from an analysis of atomic species (Mg$^0$, Fe$^0$) and excited fine-structure levels of ions (e.g., Si$^+$). Our analysis is guided …
We report on a survey for strong (rest equivalent width W$_r$>=1 ̊A), intervening Mg II systems along the sight lines to long-duration gamma-ray bursts (GRBs). The GRB spectra that comprise the survey have a heterogeneous mix of resolution and …
Excited Si$^+$ and Fe$^+$ species are routinely observed in the host environment of gamma-ray burst (GRB) afterglows but are not commonly seen in other extragalactic locations. Their presence signals unusual properties in the gaseous environment of …
Observations show that at least some gamma-ray bursts (GRBs) happen simultaneously with core-collapse supernovae (SNe), thus linking by a common thread nature's two grandest explosions. We review here the growing evidence for and theoretical …
The bright GRB 050408 was localized by HETE-2 near local midnight in the Western Hemisphere, enabling an impressive ground-based follow- up effort, as well as space-based follow-up from Swift. The Swift data from the XRT and our own optical …
We present optical and infrared monitoring of the 2005 outburst of the halo black hole X-ray transient XTE J1118+480. We measured a total outburst amplitude of åisebox-0.5ex 5.7+/-0.1 mag in the R band and i̊sebox-0.5ex 5 mag in the infrared J, H, …
The pursuit of the progenitors of short duration-hard spectrum gamma-ray bursts (SHBs) draws strongly upon similar quests for the origin of supernovae (SNe) and long duration-soft spectrum GRBs (LSBs). Indeed the notion that, in the absence of …
We report observations of GRB 050525A, for which a Gemini North spectrum shows its redshift to be z=0.606. This is the third closest long GRB discovered by Swift. We observed its afterglow using the VLT, Gemini, and TNG telescopes to search for an …