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

TL;DR

This paper reports optical polarization measurements of two gamma-ray burst afterglows, providing insights into jet magnetization and proposing a unified model to explain the observations.

Contribution

It presents the first polarization measurements for GRB 060418 and GRB 090102, offering new data to test models of GRB jet magnetization.

Findings

GRB 060418 has an upper polarization limit of <8%.

GRB 090102 shows a polarization of 10 +/- 1%.

Results support models involving magnetized jets.

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.