تقرير
Soft X-ray absorption excess in gamma-ray burst afterglow spectra: Absorption by turbulent ISM
| العنوان: | Soft X-ray absorption excess in gamma-ray burst afterglow spectra: Absorption by turbulent ISM |
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| المؤلفون: | Tanga, M., Schady, P., Gatto, A., Greiner, J., Krause, M. G. H., Diehl, R., Savaglio, S., Walch, S. |
| سنة النشر: | 2016 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies |
| الوصف: | Two-thirds of long duration gamma-ray bursts (GRBs) show soft X-ray absorption in excess of the Milky Way. The column densities of metals inferred from UV and optical spectra differ from those derived from soft X-ray spectra, at times by an order of magnitude, with the latter being higher. The origin of the soft X-ray absorption excess observed in GRB X-ray afterglow spectra remains a heavily debated issue, which has resulted in numerous investigations on the effect of hot material both internal and external to the GRB host galaxy on our X-ray afterglow observations. Nevertheless, all models proposed so far have either only been able to account for a subset of our observations (i.e. at z > 2), or they have required fairly extreme conditions to be present within the absorbing material. In this paper, we investigate the absorption of the GRB afterglow by a collisionally ionised and turbulent interstellar medium (ISM). We find that a dense (3 per cubic centimeters) collisionally ionised ISM could produce UV/optical and soft X-ray absorbing column densities that differ by a factor of 10, however the UV/optical and soft X-ray absorbing column densities for such sightlines and are 2-3 orders of magnitude lower in comparison to the GRB afterglow spectra. For those GRBs with a larger soft X-ray excess of up to an order of magnitude, the contribution in absorption from a turbulent ISM as considered here would ease the required conditions of additional absorbing components, such as the GRB circumburst medium and intergalactic medium. Comment: 9 pages, 7 figures. Accepted for publication in A&A |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1051/0004-6361/201527961 |
| URL الوصول: | http://arxiv.org/abs/1603.05123 |
| رقم الأكسشن: | edsarx.1603.05123 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1051/0004-6361/201527961 |
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