The high-redshift gamma-ray burst GRB 140515A A comprehensive X-ray and optical study
Number of Authors: 25
2015 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 581, A86Article in journal (Refereed) Published
High-redshift eamma-ray bursts (GRBs) offer several advantages When studying the distant Universe, providing unique information about the structure and properties of the galaxies in which they exploded. Spectroscopic identification with large ground-based telescopes has improved our knowledge of this kind of distant events. We present the multi-wavelength analysis of the high-z S'wift GRB GRB 1.40515A (z = 6.327). The best estimate of the neutral hydrogen fraction of the intergalactic medium towards the burst is X-HI <= 0.002. The spectral absorption lines detected for this event are the weakest lines ever observed in GRB afterglows, suggesting that GRB 140515A exploded in a very low-density environment. Its circtun-burst medium is characterised by an average extinction (A(V) similar to 0.1) that seems to be typical of z >= 6 events. The observed multi-band light curves are explained either with a very hard injected spectrum (p = 1.7) or with a multi-component emission (p = 2.1). In the second case a long-lasting central engine activity is needed in order to explain the late time X-ray emission. The possible origin of GRB 140515A in a Pop III (or in a Pop II star with a local environment enriched by Pop III) massive star is unlikely.
Place, publisher, year, edition, pages
2015. Vol. 581, A86
gamma-ray burst: general, gamma-ray burst: individual: GRB 140515A, galaxies: high-redshift, intergalactic medium
IdentifiersURN: urn:nbn:se:su:diva-122768DOI: 10.1051/0004-6361/201526660ISI: 000361803900086OAI: oai:DiVA.org:su-122768DiVA: diva2:868815