# Systematic study for gas-to-dust ratio of short gamma-ray burst afterglows

## TL;DR

This study analyzes the gas-to-dust ratio in short gamma-ray burst afterglows, revealing it is similar to the Milky Way's ratio and suggesting SGRBs occur in non star-forming regions of host galaxies.

## Contribution

It provides the first systematic measurement of the gas-to-dust ratio in short GRB afterglows, linking it to the interstellar medium of host galaxies.

## Key findings

- SGRBs have a lower N^{rest}_{H}/A^{rest}_{V} ratio than long GRBs.
- The ratio in SGRBs is consistent with the Milky Way's gas-to-dust ratio.
- Results support SGRBs occurring in non star-forming regions.

## Abstract

Extra-galactic X-ray absorption and optical extinction are often found in gamma-ray burst (GRB) afterglows and they could be tracers of both circumburst and host galaxy environments. By performing spectral analyses for spectral energy distribution of 9 short GRB (SGRB) afterglows with known redshift, we investigated a ratio of the equivalent hydrogen column density to the dust extinction, N^{rest}_{H}/A^{rest}_{V}, in the rest frame of each SGRB. We found that the distribution of N^{rest}_{H}/A^{rest}_{V} is systematically smaller than the one for long GRBs, and is roughly consistent with the gas-to-dust ratio in the Milky Way. This result means that the measured gas-to-dust ratio of SGRBs would originate from the interstellar medium in each host galaxy. This scenario supports the prediction that SGRBs occur in non star-forming regions in the host galaxies.