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Detailed multi-wavelength modelling of the dark GRB 140713A and its host galaxy

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posted on 23.09.2019, 16:40 by AB Higgins, AJVD Horst, RLC Starling, G Anderson, D Perley, HV Eerten, K Wiersema, P Jakobsson, C Kouveliotou, GP Lamb, NR Tanvir
We investigate the afterglow of GRB 140713A, a gamma-ray burst (GRB) that was detected and relatively well sampled at X-ray and radio wavelengths, but was not present at optical and near-infrared wavelengths, despite searches to deep limits. We present the emission spectrum of the likely host galaxy at z = 0.935 ruling out a high-redshift explanation for the absence of the optical flux detection. Modelling the GRB multiwavelength afterglow using the radiative transfer hydrodynamics code BOXFIT provides constraints on physical parameters of the GRB jet and its environment, for instance a relatively wide jet opening angle and an electron energy distribution slope p below 2. Most importantly, the model predicts an optical flux about two orders of magnitude above the observed limits. We calculated that the required host extinction to explain the observed limits in the r, i, and z bands was AhostV>3.2 mag, equivalent to E(B − V)host > 1.0 mag. From the X-ray absorption we derive that the GRB host extinction is AhostV=11.6+7.5−5.3 mag, equivalent to E(B−V)host=3.7+2.4−1.7 mag, which is consistent with the extinction required from our BOXFIT derived fluxes. We conclude that the origin of the optical darkness is a high level of extinction in the line of sight to the GRB, most likely within the GRB host galaxy.


We greatly appreciate the support from the WSRT and AMI staff in their help with scheduling and obtaining these observations. The WSRT is operated by ASTRON (Netherlands Institute for Radio Astronomy) with support from the Netherlands foundation for Scientific Research. The AMI arrays are supported by the University of Cambridge and the STFC. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration (NASA); the Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The Nordic Optical Telescope is operated on the island of La Palma by the Nordic Optical Telescope Scientific Association in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. ABH is supported by a Science and Technology Facilities Council (STFC) studentship. RLCS, KW and NRT acknowledge support from STFC. GA acknowledges the support of the European Research Council Advanced Grant 267697 ‘4 Pi Sky: Extreme Astrophysics with Revolutionary Radio Telescopes’. GA is the recipient of an Australian Research Council Discovery Early Career Researcher Award (project number DE180100346) funded by the Australian Government.



Monthly Notices of the Royal Astronomical Society, 2019, 484(4), pp. 5245–5255

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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Monthly Notices of the Royal Astronomical Society


Oxford University Press (OUP), Royal Astronomical Society



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