Core collapse supernovae as Cosmic Ray sources

TL;DR

This paper investigates how core collapse supernovae can accelerate cosmic rays to PeV energies through shock-induced magnetic field amplification, highlighting the importance of dense circum-stellar media and shock speed.

Contribution

It provides a self-similar model for CR-driven instabilities in supernova shocks and links radio observations to CR acceleration potential in different supernova types.

Findings

Extended IIb supernova shocks can trigger rapid instabilities and magnetic field amplification.

Non-resonant streaming instability can account for about 50% of observed magnetic fields.

CRs up to 1-10 PeV can be accelerated within days after shock breakout.

Abstract

Core collapse supernovae (CCSNe) produce fast shocks which pervade the dense circum-stellar medium (CSM) of the stellar progenitor. Cosmic rays (CRs) if accelerated at these shocks can induce the growth of electromagnetic fluctuations in the foreshock medium. In this study, using a self-similar description of the shock evolution, we calculate the growth timescales of CR-driven instabilities. We select a sample of nearby core collapse radio supernova of type II and Ib/Ic. From radio data we infer the parameters which enter in the calculation of the instability growth times. We find that extended IIb SNe shocks can trigger fast intra day instabilities, strong magnetic field amplification and CR acceleration. In particular, the non-resonant streaming instability can contribute to about 50\% of the magnetic field intensity deduced from radio data. This results in the acceleration of CRs in the range 1-10 PeV within a few days after the shock breakout. In order to produce strong magnetic field amplification and CR acceleration a fast shocks pervading a dense CSM is necessary. In that aspect IIn supernov\ae~are also good candidates. But a detailed modeling of the blast wave dynamics coupled with particle acceleration is mandatory for this class of object before providing any firm conclusions. Finally, we find that the trans-relativistic object SN 2009bb even if it produces more modest magnetic field amplification can accelerate CRs up to 2-3 PeV within 20 days after the outburst.