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GRB 090313 and the Origin of Optical Peaks in Gamma-Ray Burst Light Curves: Implications for Lorentz Factors and Radio Flares

Melandri, A and Kobayashi, S and Mundell, CG and Guidorzi, C and Postigo, ADU and Pooley, G and Yoshida, M and Bersier, D and Castro-Tirado, AJ and Jelinek, M and Gomboc, A and Gorosabel, J and Kubanek, P and Bremer, M and Winters, JM and Steele, IA and de Gregorio-Monsalvo, I and Smith, RJ and Garcia-Appadoo, D and Sota, A and Lundgren, A (2010) GRB 090313 and the Origin of Optical Peaks in Gamma-Ray Burst Light Curves: Implications for Lorentz Factors and Radio Flares. Astrophysical Journal, 723 (2). ISSN 0004-637X

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Abstract

We use a sample of 19 gamma-ray bursts (GRBs) that exhibit single-peaked optical light curves to test the standard fireball model by investigating the relationship between the time of the onset of the afterglow and the temporal rising index. Our sample includes GRBs and X-ray flashes for which we derive a wide range of initial Lorentz factors (40 < Γ < 450). Using plausible model parameters, the typical frequency of the forward shock is expected to lie close to the optical band; within this low typical frequency framework, we use the optical data to constrain epsilon e and show that values derived from the early time light-curve properties are consistent with published typical values derived from other afterglow studies. We produce expected radio light curves by predicting the temporal evolution of the expected radio emission from forward and reverse shock components, including synchrotron self-absorption effects at early time. Although a number of GRBs in this sample do not have published radio measurements, we demonstrate the effectiveness of this method in the case of Swift GRB 090313, for which millimetric and centimetric observations were available, and conclude that future detections of reverse-shock radio flares with new radio facilities such as the EVLA and ALMA will test the low-frequency model and provide constraints on magnetic models.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical And Space Sciences, 0305 Organic Chemistry, 0306 Physical Chemistry (Incl. Structural)
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Q Science > QD Chemistry
Divisions: Astrophysics Research Institute
Publisher: American Astronomical Society; IOP Publishing
Related URLs:
Date Deposited: 19 Jan 2017 09:01
Last Modified: 09 Sep 2017 03:15
DOI or Identification number: 10.1088/0004-637X/723/2/1331
URI: http://researchonline.ljmu.ac.uk/id/eprint/5285

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