Early time optical polarization of GRB Afterglows: GRB 060418 and GRB 090102

Abstract

RINGO on the Liverpool Telescope has now measured the optical polarization of GRB 060418 (where a 2 sigma upper limit of P<8% was determined) and GRB 090102 (when a detection of P = 10 +/-1 % was made). We discuss the implications of these observations for the various competing models of GRB jet magnetization and describe a possible unified model that can explain both measurements.

To appear in proceedings of "The Shocking Universe" conference held in San Servolo, 2009