Polarimetry and Photometry of Gamma-Ray Bursts with RINGO2

Abstract

We present a catalog of early-time (~10^2-10^4s) photometry and polarimetry of all Gamma-Ray Burst (GRB) optical afterglows observed with RINGO2 imaging polarimeter on the Liverpool Telescope. For the 19 optical afterglows observed, the following 9 were bright enough to perform photometry and attempt polarimetry: GRB 100805A, GRB 101112A, GRB 110205A, GRB 110726A, GRB 120119A, GRB 120308A, GRB 120311A, GRB 120326A and GRB 120327A. We present multi-wavelength light curves for these 9 GRBs, together with estimates of their optical polarization degrees and/or limits. We carry out a thorough investigation of detection probabilities, instrumental properties and systematics. Using two independent methods, we confirm previous reports of significant polarization in GRB 110205A and 120308A, and report new detection of $P=6_{-2}^{+3}\%$ in GRB101112A. We discuss the results for the sample in the context of the reverse and forward shock afterglow scenario, and show that GRBs with detectable optical polarization at early time have clearly identifiable signatures of reverse-shock emission in their optical light curves. This supports the idea that GRB ejecta contain large-scale magnetic fields and highlights the importance of rapid-response polarimetry.

Accepted for Publication in ApJ (12th June 2017)

References in corpus (10)

• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• Gamma-Ray Bursts: Progress, Problems & Prospects
• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• Magnetic acceleration of ultra-relativistic jets in gamma-ray burst sources
• Ten per cent polarized optical emission from GRB 090102
• Circular polarization in the optical afterglow of GRB 121024A
• Phenomenology of Reverse-Shock Emission in the Optical Afterglows of Gamma Ray Bursts
• The RINGO2 and DIPOL Optical Polarisation Catalogue of Blazars
• The nature of the late achromatic bump in GRB 120326A
• Polarization of gamma-ray burst afterglows in the synchrotron self-Compton process from a highly relativistic jet

Cited by in corpus (5)

• Characterization of a dual-beam, dual-camera optical imaging polarimeter
• Coherence scale of magnetic fields generated in early-time forward shocks of GRBs
• Colour variations in the GRB 120327A afterglow
• Time-resolved image polarimetry of Trappist-1 during planetary transits
• Optical Polarimetry of KIC 8462852 in May-August 2017