Probing the Interstellar Medium and Stellar Environments of Long-Duration GRBs

Abstract

Abstract.We review the properties of the gas surrounding high-redshift gamma-ray bursts (GRBs) assessed through the analysis of damped Lyman-alpha systems (DLAs) identified in their afterglow spectra. These GRB-DLAs are characterized by large H I column densities with a median of N (H I) = 10 21. 7 cm −2 , no molecular gas signatures, metallicities ranging from 1/100 to nearly solar with a median exceeding 1/10 solar, and no anomalous abundance patterns. The detection of the atomic Mg lines and the time-variability of the fine-structure lines demonstrates that the majority of the neutral gas along the GRB sightlines is located between 50 pc and a few kpc from the GRB. This implies that this gas is presumably associated with the ambient interstellar medium of the host galaxy and that the derived properties from low-ionization lines do not directly constrain the local environment of the GRB progenitor. The highly ionized gas, traced by N V lines, which could result from a pre-existing H II region produced by the GRB progenitor and neighboring OB stars, appears on the other hand to be very local to the GRB at about 10 pc, yielding a snapshot of the medium's physical conditions at this radius.

Investigating the Evolution of Amati Parameters with Redshift

“…The ability to identify GRBs up to extremely high redshifts has long piqued the interest of cosmologists. Long GRBs provide a unique opportunity to investigate the properties of galaxies at high redshift, including galaxy evolution, star formation rate, and the intergalactic medium and interstellar medium (ISM) (Woosley & Bloom 2006;Dessauges-Zavadsky et al 2008;Fynbo et al 2009;Salvaterra et al 2009;Tanvir et al 2009;Cucchiara et al 2011;Wang et al 2015). In the last two decades, various relations between different observational parameters have been discovered, such as the Amati relation and Ghirlanda relation (Bloom et al 2003;Ghirlanda et al 2004;Donaghy et al 2005;Friedman & Bloom 2005;Firmani et al 2006;Schaefer 2007).…”