A comprehensive radio view of the extremely bright gamma-ray burst 130427A
Journal article, 2014
GRB130427A was extremely bright as a result of occurring at low redshift whilst the energetics were more typical of high-redshift gamma-ray bursts (GRBs). We collected well-sampled light curves at 1.4 and 4.8 GHz of GRB 130427A with the Westerbork Synthesis Radio Telescope (WSRT); and we obtained its most accurate position with the European Very Long Baseline Interferometry Network (EVN). Our flux density measurements are combined with all the data available at radio, optical and X-ray frequencies to perform broad-band modelling in the framework of a reverse-forward shock model and a two-component jet model, and we discuss the implications and limitations of both models. The low density inferred from the modelling implies that the GRB 130427A progenitor is either a very low metallicity Wolf-Rayet star, or a rapidly rotating, low-metallicity O star. We also find that the fraction of the energy in electrons is evolving over time, and that the fraction of electrons participating in a relativistic power-law energy distribution is less than 15 per cent. We observed intraday variability during the earliest WSRT observations, and the source sizes inferred from our modelling are consistent with this variability being due to interstellar scintillation effects. Finally, we present and discuss our limits on the linear and circular polarization, which are among the deepest limits of GRB radio polarization to date.
gamma-ray burst: individual: GRB 130427A
GRB 130427A
Author
A. J. van der Horst
University of Amsterdam
Z. Paragi
Joint Institute for VLBI in Europe (JIVE)
A. G. de Bruyn
University of Groningen
Netherlands Institute for Radio Astronomy (ASTRON)
J. Granot
Open University of Israel
C. Kouveliotou
National Aeronautics and Space Administration (NASA)
K. Wiersema
University Of Leicester
R. L. C. Starling
University Of Leicester
P. A. Curran
Curtin University
Ramj Wijers
University of Amsterdam
A. Rowlinson
University of Amsterdam
G. A. Anderson
University of Oxford
University of Southampton
R. P. Fender
University of Southampton
University of Oxford
Jun Yang
Chalmers, Earth and Space Sciences, Onsala Space Observatory
R. G. Strom
Netherlands Institute for Radio Astronomy (ASTRON)
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 444 4 3151-3163Advanced Radio Astronomy in Europe (RADIONET3)
European Commission (EC) (EC/FP7/283393), 2012-01-01 -- 2015-12-31.
Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1093/mnras/stu1664