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arXiv 1808.09228astro-ph.GAastro-ph.HE
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GRB宿主星系中的红外分子氢线

Infrared molecular hydrogen lines in GRB host galaxies

K. Wiersema, A. Togi, D. Watson, L. Christensen, J. P. U. Fynbo, B. P. Gompertz, A. B. Higgins, A. J. Levan, S. R. Oates, S. Schulze, J. D. T. Smith, E. R. Stan… 展开作者

K. Wiersema, A. Togi, D. Watson, L. Christensen, J. P. U. Fynbo, B. P. Gompertz, A. B. Higgins, A. J. Levan, S. R. Oates, S. Schulze, J. D. T. Smith, E. R. Stanway, R. L. C. Starling, D. Steeghs, N. R. Tanvir

摘要:

分子种类,最常见的是H_2,存在于一个小的,但越来越多的伽马射线暴(GRB)余辉光谱红移z~2-3,通过其休息框架的紫外吸收线检测。在极少数情况下,H_2的振动激发态谱线可以在同一谱线中探测到。分子(和原子)气体的余辉视线吸收特性之间的联系,以及在低红移的类似源的发射中观察到的行为,是一个重要的测试伽玛射线暴余辉作为恒星形成区域在高红移条件的一般探针的适用性。最近,在伽玛暴宿主星系的一个小样本中探测到了亚毫米波长的一氧化碳发射线,但还没有在发射线中寻找H_2的报道。本文探索性地研究了H_2在静止坐标系K带的转动-振动跃迁,这种跃迁只能在红移最低的GRB宿主(z<0.22)中观测到。通过对四个宿主星系的观测数据的搜索,我们在GRB 031203的宿主星系中探测到了一条重要的转动-振动H_2谱线。对同一伽玛暴主体的斯皮策中红外光谱的重新分析给出了一条低显著性旋转线候选者。线通量比的(限制)与文献中的蓝致密矮星系一致。新的仪器,特别是JWST和ELT上的仪器,可以大大增加我们对附近GRB宿主的H_2性质的理解,以及在高红移处GRB中H_2吸收与H_2吸收的关系。

英文摘要:

Molecular species, most frequently H_2, are present in a small, but growing, number of gamma-ray burst (GRB) afterglow spectra at redshifts z~2-3, detected through their rest-frame UV absorption lines. In rare cases, lines of vibrationally excited states of H_2 can be detected in the same spectra. The connection between afterglow line-of-sight absorption properties of molecular (and atomic) gas, and the observed behaviour in emission of similar sources at low redshift, is an important test of the suitability of GRB afterglows as general probes of conditions in star formation regions at high redshift. Recently, emission lines of carbon monoxide have been detected in a small sample of GRB host galaxies, at sub-mm wavelengths, but no searches for H_2 in emission have been reported yet. In this paper we perform an exploratory search for rest-frame K band rotation-vibrational transitions of H_2 in emission, observable only in the lowest redshift GRB hosts (z<0.22). Searching the data of four host galaxies, we detect a single significant rotation-vibrational H_2 line candidate, in the host of GRB 031203. Re-analysis of Spitzer mid-infrared spectra of the same GRB host gives a single low significance rotational line candidate. The (limits on) line flux ratios are consistent with those of blue compact dwarf galaxies in the literature. New instrumentation, in particular on the JWST and the ELT, can facilitate a major increase in our understanding of the H_2 properties of nearby GRB hosts, and the relation to H_2 absorption in GRBs at higher redshift.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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