Extremely narrow spectrum of GRB110920A: further evidence for localized, subphotospheric dissipation
2015 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 450, no 2, 1651-1663 p.Article in journal (Refereed) Published
Much evidence points towards that the photosphere in the relativistic outflow in GRBs plays an important role in shaping the observed MeV spectrum. However, it is unclear whether the spectrum is fully produced by the photosphere or whether a substantial part of the spectrum is added by processes far above the photosphere. Here we make a detailed study of the. ray emission from single pulse GRB110920A which has a spectrum that becomes extremely narrow towards the end of the burst. We show that the emission can be interpreted as Comptonization of thermal photons by cold electrons in an unmagnetized outflow at an optical depth of tau similar to 20. The electrons receive their energy by a local dissipation occurring close to the saturation radius. The main spectral component of GRB110920A and its evolution is thus, in this interpretation, fully explained by the emission from the photosphere including localized dissipation at high optical depths.
Place, publisher, year, edition, pages
2015. Vol. 450, no 2, 1651-1663 p.
IdentifiersURN: urn:nbn:se:kth:diva-170964DOI: 10.1093/mnras/stv636ISI: 000356338500039OAI: oai:DiVA.org:kth-170964DiVA: diva2:841464
QC 201507132015-07-132015-07-132015-07-13Bibliographically approved