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

Abstract

We present a polarization study towards the supernova remnant (SNR) Puppis A based on original observations performed with the Australia Telescope Compact Array (ATCA). Based on the analysis of a feature detected outside the SNR shell (called 'the tail' throughout the paper), it was possible to disentangle the emission with origin in Puppis A itself from that coming from the foreground Vela SNR. We found a very low polarization fraction, of about 3 percent on average. The upper limit of the magnetic field component parallel to the line of sight is estimated to be B ∼ 20 µG. The statistical behavior of the magnetic vectors shows two preferential directions, almost perpendicular to each other, which are approximately aligned with the flat edges of Puppis A. A third, narrow peak oriented perpendicular to the Galactic plane suggests the existence of an interstellar magnetic field locally aligned in this direction. There is evidence that the magnetic vectors along the shell are aligned with the shock front direction. The low polarization fraction and the statistical behavior of the magnetic vectors are compatible with a scenario where the SNR evolves inside a stellar wind bubble with a box-like morphology, produced by the interaction of the different stellar winds, one of them magnetized, launched by the SN progenitor. This scenario can furthermore explain the morphology of Puppis A, rendering little support to the previously accepted picture which involved strong density gradients to explain the flat, eastern edge of the shell.

Evolving supernova remnants in multiphase interstellar media

“…Thermal x-ray spectrum for BLT (red) and BHT (blue) after 3900 years chrotron radiation of SNRs both in its amplified or in its pre-contact state. In fact, works like the ones by Reynoso et al (2018) argue that the ISM magnetic field may be detectable even after being in contact with a SNR shock front. Simulations have also been used to study the orientation or reorientation of the magnetic field of the ISM after the passage of a SNR, for example Bao et al (2018) simulated the expansion of a SNR in a media with a magnetic field with an ordered component finding that different lines of sight produce different polarization maps.…”

Molecular and Atomic Clouds Associated with the Gamma-Ray Supernova Remnant Puppis A

“…Here, by adopting t age > 10,000 yr, E = 10 GeV, and B < 20 μG (Reynoso et al 2018), we obtain a cosmic-ray diffusion length of l diff > 22 pc. The length becomes large with E and is larger than the SNR radius of ∼10 pc, supporting the escape of the cosmic rays.…”

Molecular and Atomic Clouds Associated with the Gamma-Ray Supernova Remnant Puppis A

“…Here, by adopting t age > 10000 yr, E = 10 GeV, B < 20 µG (Reynoso et al 2018), we obtain the cosmic-ray diffusion length l diff > 22 pc. The length becomes large with E and is larger than the SNR radius ∼10 pc, supporting the escape of the cosmic rays.…”