http://arxiv.org/abs/1903.05963
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.
K. Yoshida, D. Yonetoku, M. Arimoto, et. al.
Fri, 15 Mar 19
53/67
Comments: 15 pages, 4 figures
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