# ISM: Molecules

## The Discovery of Vibrationally Excited H$_2$ in the Molecular Cloud Near GRB 080607

GRB 080607 has provided the first observational signatures of molecular absorption bands toward any galaxy hosting a gamma-ray burst (GRB). Despite the identification of dozens of features as belonging to various atomic and molecular (H$_2$ and CO) …

## The First Positive Detection of Molecular Gas in a GRB Host Galaxy

We report on strong H$_2$ and CO absorption from gas within the host galaxy of gamma-ray burst (GRB) 080607. Analysis of our Keck/LRIS afterglow spectrum reveals a very large H I column density (N_H I = 10̂22.70 ± 0.15 cm-̂2) and strong metal-line …

## Missing Molecular Hydrogen and the Physical Conditions of GRB Host Galaxies

We examine the abundance of molecular hydrogen (H$_2$) in the spectra of gamma ray burst afterglows (GRBs). In nearby galaxies, H$_2$ traces the cold neutral medium (CNM) and dense molecular star-forming interstellar gas. Although H$_2$ is detected …