NuSTAR Observations of GRB 130427A Establish a Single Component Synchrotron Afterglow Origin for the Late Optical to Multi-GeV Emission
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/Large Area Telescope >10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2013
- DOI:
- 10.1088/2041-8205/779/1/L1
- arXiv:
- arXiv:1311.5245
- Bibcode:
- 2013ApJ...779L...1K
- Keywords:
-
- acceleration of particles;
- gamma-ray burst: individual: GRB 130427A;
- magnetic fields;
- radiation mechanisms: non-thermal;
- shock waves;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 5 pages, 3 figures, accepted by ApJL