Synchrotron Self-inverse Compton Radiation from Reverse Shock on GRB 120326A
Abstract
We present multi-wavelength observations of a typical long duration GRB 120326A at z = 1.798, including rapid observations using a Submillimeter Array (SMA) and a comprehensive monitoring in the X-ray and optical. The SMA observation provided the fastest detection to date among seven submillimeter afterglows at 230 GHz. The prompt spectral analysis, using Swift and Suzaku, yielded a spectral peak energy of E^src_peak=107.8^{+15.3}_{-15.3} keV and an equivalent isotropic energy of E iso as 3.18^{+0.40}_{-0.32}\times 10^{52} erg. The temporal evolution and spectral properties in the optical were consistent with the standard forward shock synchrotron with jet collimation (6.°69 ± 0.°16). The forward shock modeling, using a two-dimensional relativistic hydrodynamic jet simulation, was also determined by the reasonable burst explosion and the synchrotron radiation parameters for the optical afterglow. The X-ray light curve showed no apparent jet break and the temporal decay index relation between the X-ray and optical (αo - α X = -1.45 ± 0.10) indicated different radiation processes in each of them. Introducing synchrotron self-inverse Compton radiation from reverse shock is a possible solution, and the detection and slow decay of the afterglow in submillimeter supports that this is a plausible idea. The observed temporal evolution and spectral properties, as well as forward shock modeling parameters, enabled us to determine reasonable functions to describe the afterglow properties. Because half of the events share similar properties in the X-ray and optical as the current event, GRB 120326A will be a benchmark with further rapid follow-ups, using submillimeter instruments such as an SMA and the Atacama Large Millimeter/submillimeter Array.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2014
- DOI:
- 10.1088/0004-637X/789/2/146
- arXiv:
- arXiv:1405.4331
- Bibcode:
- 2014ApJ...789..146U
- Keywords:
-
- gamma-ray burst: individual: 120326a;
- radiation mechanisms: non-thermal;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 25 pages, 7 figures, 2 tables, accepted for publication in ApJ