Optical Afterglows and IGM Attenuation

TL;DR

This paper models the attenuation of gamma-ray burst optical afterglows by intergalactic absorbers, providing magnitude correction estimates across redshifts for common filters, aiding accurate cosmological observations.

Contribution

It offers a comprehensive set of magnitude correction calculations for GRB afterglows due to IGM attenuation, accessible online, improving upon previous semi-analytical and simulation methods.

Findings

Magnitude corrections vary with redshift and filter.

Results are publicly available for community use.

Provides a standardized correction framework for GRB observations.

Abstract

Because of their cosmological origin, gamma-ray burst (GRB) optical afterglows are attenuated when they pass intergalactic absorbers in the GRB line-of-sight. Without the knowledge of the number of absorbers and their physical properties, the effect of absorption on the observed magnitudes can not be determined precisely. Different methods have been applied in order to correct for this effect statistically, either using semi-analytical calculations or numerical simulations. We follow these works and present the expected magnitude corrections as a function of redshift for a set of filters most commonly used in the scientific community. The results are publically available on the web (http://igmac.fmf.uni-lj.si).