We report on the polarization properties of two fast radio bursts ( FRBs ) : 151230 and 160102 discovered in the SUrvey for Pulsars and Extragalactic Radio Bursts ( SUPERB ) at the Parkes radio telescope .
FRB 151230 is observed to be 6 \pm 11 \% circularly polarized and 35 \pm 13 % linearly polarized with a rotation measure ( RM ) consistent with zero .
Conversely , FRB 160102 is observed to have a circular polarization fraction of 30 \pm 11 % , linear polarization fraction of 84 \pm 15 % for RM = -221 ( 6 ) rad m ^ { -2 } and the highest measured DM ( 2596.1 \pm 0.3 pc cm ^ { -3 } ) for an FRB to date .
We examine possible progenitor models for FRB 160102 in extragalactic , non-cosmological and cosmological scenarios .
After accounting for the Galactic foreground contribution , we estimate the intrinsic RM to be -256 ( 9 ) rad m ^ { -2 } in the low-redshift case and \sim - 2.4 \times 10 ^ { 2 } rad m ^ { -2 } in the high-redshift case .
We assess the relative likeliness of these scenarios and how each can be tested .
We also place constraints on the scattering measure and study the impact of scattering on the signal ’ s polarization position angle .