Prochaska 2007 用伽玛暴余辉的谱探测恒星形成区的ISM

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文章信息:
Probing the ISM Near Star Forming Regions with GRB Afterglow Spectroscopy: Gas, Metals, and Dust

Authors: Jason X. Prochaska (1), Hsiao-Wen Chen (2), Miroslava Dessauges-Zavadsky (3), Joshua S. Bloom (4) ((1) UCO/Lick Observatory, (2) U Chicago, (3) Observatoire de Geneve, (4) UC Berkeley)

(Submitted on 26 Mar 2007)

Abstract: We study the chemical abundances of the interstellar medium surrounding high z gamma-ray bursts (GRBs) through analysis of the damped Lya systems (DLAs) identified in afterglow spectra. These GRB-DLAs are characterized by large HI column densities N(HI) and metallicities [M/H] spanning 1/100 to nearly solar, with median [M/H]>-1. The majority of GRB-DLAs have [M/H] values exceeding the cosmic mean metallicity of atomic gas at z>2, i.e. if anything, the GRB-DLAs are biased to larger metallicity. We also observe (i) large [Zn/Fe] values (>+0.6) and sub-solar Ti/Fe ratios which imply substantial differential depletion, (ii) large a/Fe ratios suggesting nucleosynthetic enrichment by massive stars, and (iii) low C^0/C^+ ratios (<10^{-4}).>

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16 pages, 9 figures. Submitted to ApJ

Subjects:

Astrophysics (astro-ph)

Cite as:

arXiv:astro-ph/0703665v1