New perspectives on the supernova remnant Puppis A based on a radio polarization study

REYNOSO, E M; VELÁZQUEZ, P F; CICHOWOLSKI, S

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2018

0035-8711

We present a polarization study towards the supernova remnant (SNR)Puppis A based on original observations performed with the AustraliaTelescope Compact Array (ATCA). Based on the analysis of a featuredetected outside the SNR shell (called `the tail´ throughout the paper),it was possible to disentangle the emission with origin in Puppis Aitself from that coming from the foreground Vela SNR. We found a verylow polarization fraction, of about 3 percent on average. The upperlimit of the magnetic field component parallel to the line of sight isestimated to be B∥ ? 20 μG. The statisticalbehavior of the magnetic vectors shows two preferential directions,almost perpendicular to each other, which are approximately aligned withthe flat edges of Puppis A. A third, narrow peak oriented perpendicularto the Galactic plane suggests the existence of an interstellar magneticfield locally aligned in this direction. There is evidence that themagnetic vectors along the shell are aligned with the shock frontdirection. The low polarization fraction and the statistical behavior ofthe magnetic vectors are compatible with a scenario where the SNRevolves inside a stellar wind bubble with a box-like morphology,produced by the interaction of the different stellar winds, one of themmagnetized, launched by the SN progenitor. This scenario can furthermoreexplain the morphology of Puppis A, rendering little support to thepreviously accepted picture which involved strong density gradients toexplain the flat, eastern edge of the shell.