The high-redshift gamma-ray burst GRB: A comprehensive X-ray and optical study

DOI: 
10.1051/0004-6361/201526660
Publication date: 
01/09/2015
Main author: 
Melandri A.
IAA authors: 
Sánchez-Ramírez R.;De Ugarte Postigo A.;Oates S.;Gorosabel J.;Thöne C.C.
Authors: 
Melandri A., Bernardini M.G., D'Avanzo P., Sánchez-Ramírez R., Nappo F., Nava L., Japelj J., De Ugarte Postigo A., Oates S., Campana S., Covino S., D'Elia V., Ghirlanda G., Gafton E., Ghisellini G., Gnedin N., Goldoni P., Gorosabel J., Libbrecht T., Malesani D., Salvaterra R., Thöne C.C., Vergani S.D., Xu D., Tagliaferri G.
Journal: 
Astronomy and Astrophysics
Publication type: 
Article
Volume: 
581
Pages: 
Number: 
A86
Abstract: 
High-redshift gamma-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-zSwift GRB GRB€‰140515A (z = 6.327). The best estimate of the neutral hydrogen fraction of the intergalactic medium towards the burst is x≤ 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 circum-burst medium is characterised by an average extinction (A∼ 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. © ESO.
Database: 
SCOPUS
WOK
ADS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2015A&A...581A..86M/abstract
ADS Bibcode: 
2015A&A...581A..86M
Keywords: 
galaxies: high-redshift; gamma-ray burst: general; gamma-ray burst: individual: GRB 140515A; intergalactic medium