Publication Date:
2000-11-04
Description:
We report the discovery of a transient equivalent hydrogen column density with an absorption edge at approximately 3.8 kiloelectron volts in the spectrum of the prompt x-ray emission of gamma-ray burst (GRB) 990705. This feature can be satisfactorily modeled with a photoelectric absorption by a medium located at a redshift of approximately 0.86 and with an iron abundance of approximately 75 times the solar one. The transient behavior is attributed to the strong ionization produced in the circumburst medium by the GRB photons. The high iron abundance points to the existence of a burst environment enriched by a supernova along the line of sight. The supernova explosion is estimated to have occurred about 10 years before the burst. Our results agree with models in which GRBs originate from the collapse of very massive stars and are preceded by a supernova event.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Amati, L -- Frontera, F -- Vietri, M -- in 't Zand, J J -- Soffitta, P -- Costa, E -- Del Sordo, S -- Pian, E -- Piro, L -- Antonelli, L A -- Fiume, D D -- Feroci, M -- Gandolfi, G -- Guidorzi, C -- Heise, J -- Kuulkers, E -- Masetti, N -- Montanari, E -- Nicastro, L -- Orlandini, M -- Palazzi, E -- New York, N.Y. -- Science. 2000 Nov 3;290(5493):953-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Istituto di Tecnologie e Studio delle Radiazioni Extraterrestri, CNR, Via Gobetti 101, 40129 Bologna, Italy. amati@tesre.bo.cnr.it〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11062120" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
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Chemistry and Pharmacology
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Computer Science
,
Medicine
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Natural Sciences in General
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Physics
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