Testing gravitational lensing as the source of enhanced strong Mg II absorption toward gamma-ray bursts
Date
2012
Authors
Rapoport, Sharon
Onken, Christopher
Wyithe, J Stuart B
Tucker , Bradley
Levan, A. J.
Journal Title
Journal ISSN
Volume Title
Publisher
IOP Publishing
Abstract
Sixty percent of gamma-ray bursts (GRBs) reveal strong Mg II absorbing systems, which is a factor of 2times the rate seen along lines of sight to quasars. Previous studies argue that the discrepancy in the strong Mg II covering factor is most likely to be the result of either quasars being obscured due to dust or the consequence of many GRBs being strongly gravitationally lensed. We analyze observations of quasars that show strong foreground Mg II absorption. We find that GRB lines of sight pass closer to bright galaxies than would be expected for random lines of sight within the impact parameter expected for strong Mg II absorption. While this cannot be explained by obscuration in the GRB sample, it is a natural consequence of gravitational lensing. Upon examining the particular configurations of galaxies near a sample of GRBs with strong Mg II absorption, we find several intriguing lensing candidates. Our results suggest that lensing provides a viable contribution to the observed enhancement of strong Mg II absorption along lines of sight to GRBs, and we outline the future observations required to test this hypothesis conclusively.
Description
Keywords
Keywords: Gamma-ray burst: general; gravitational lensing: strong
Citation
Collections
Source
Astrophysical Journal, The
Type
Journal article
Book Title
Entity type
Access Statement
Open Access