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arXiv · 1311.5245

NuSTAR Observations of GRB130427A establish a single component synchrotron afterglow origin for the late optical to multi-GeV emission

C. Kouveliotou·J. Granot·J. L. Racusin·E. Bellm·G. Vianello·S. Oates·C. L. Fryer·S. E. Boggs·F. E. Christensen·W. W. Craig·C. D. Dermer·N. Gehrels·C. J. Hailey·F. A. Harrison·A. Melandri·J. E. McEnery·C. G. Mundell·D. K. Stern·G. Tagliaferri·W. W. Zhang
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Abstract

GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (~1.5 and 5 days). This range, where afterglow observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi and ground-based optical data, NuSTAR observations unambiguously establish a single afterglow spectral component from optical to multi-GeV energies a day after the event, which is almost certainly synchrotron radiation. Such an origin of the late-time Fermi/LAT > 10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics.

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C. Kouveliotou, J. Granot, J. L. Racusin, E. Bellm, G. Vianello, S. Oates, C. L. Fryer, S. E. Boggs, F. E. Christensen, W. W. Craig, C. D. Dermer, N. Gehrels, C. J. Hailey, F. A. Harrison, A. Melandri, J. E. McEnery, C. G. Mundell, D. K. Stern, G. Tagliaferri, W. W. Zhang. 2013-11-20. NuSTAR Observations of GRB130427A establish a single component synchrotron afterglow origin for the late optical to multi-GeV emission. https://doi.org/10.1088/2041-8205%2F779%2F1%2Fl1

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