# ISM: Abundances

## A Mature Dusty Star-forming Galaxy Hosting GRB 080607 at z = 3.036

We report the discovery of the host galaxy of Swift dark burst GRB 080607 at z $_GRB$ = 3.036. GRB 080607 is a unique case of a highly extinguished (A$_V$ ≈ 3 mag) afterglow that was yet sufficiently bright for high-quality absorption-line …

## Photometry and spectroscopy of GRB 060526: a detailed study of the afterglow and host galaxy of a z = 3.2 gamma-ray burst

Aims: With this paper we want to investigate the highly variable afterglow light curve and environment of gamma-ray burst (GRB) 060526 at z = 3.221. Methods: We present one of the largest photometric datasets ever obtained for a GRB afterglow, …

## An Imaging and Spectroscopic Study of Four Strong Mg II Absorbers Revealed by GRB 060418

We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) gsim 1 ̊A revealed by the afterglow of GRB 060418 at z $_GRB$ = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z $_GRB$, exhibit large ion …

## High-Redshift Starbursting Dwarf Galaxies Revealed by γ-Ray Burst Afterglows

We present a study of 15 long-duration γ-ray burst (GRB) host galaxies at z > 2. The GRBs are selected with available early-time afterglow spectra in order to compare interstellar medium (ISM) absorption-line properties with stellar properties of …

## Super Star Cluster NGC 1705-1: A Local Analog to the Birth Site of Long-Duration γ-Ray Bursts

Recent observations suggest that global properties of the host galaxies for long-duration γ-ray bursts (GRBs) are particularly well suited for creating the massive star progenitors of these GRBs. Motivated by the hypothesis that massive young star …

## On the Absence of Wind Signatures in GRB Afterglow Spectra: Constraints on the Wolf-Rayet Winds of GRB Progenitors

We investigate available constraints on the circumstellar medium (CSM) around long-duration γ-ray burst (GRB) progenitors from afterglow spectra. We first establish a statistical sample of five GRB afterglow spectra that have been collected and …

## Echelle Spectroscopy of a Gamma-Ray Burst Afterglow at z = 3.969: A New Probe of the Interstellar and Intergalactic Media in the Young Universe

We present an echelle spectrum of the Swift GRB 050730, obtained 4 hr after the burst using the MIKE spectrograph on the Magellan Clay telescope when the afterglow was at R=17.7. The spectrum reveals a forest of absorption features superposed on a …