• DOI:10.1093/mnras/stu1664
• Corpus ID: 52206301

A comprehensive radio view of the extremely bright gamma-ray burst 130427A

@article{Horst2014ACR,
  title={A comprehensive radio view of the extremely bright gamma-ray burst 130427A},
  author={A. van der Horst and Zsolt Paragi and A. G. de Bruyn and Jonathan Granot and Chryssa Kouveliotou and Klaas Wiersema and Rhaana L. C. Starling and Peter A. Curran and Ralph Wijers and Antonia Rowlinson and G. Anderson and Robert P. Fender and J. Yang and Richard G. Strom},
  journal={Monthly Notices of the Royal Astronomical Society},
  year={2014},
  volume={444},
  pages={3151-3163}
}

• A. Horst, Z. Paragi, +11 authors R. Strom
• Published 7 April 2014
• Physics
• Monthly Notices of the Royal Astronomical Society

GRB130427Awasextremelybrightasaresultofoccurringatlowredshiftwhilsttheenergetics 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 BaselineInterferometryNetwork(EVN).Ourfluxdensitymeasurementsarecombinedwithall 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.