Nonthermal Radiation from Type Ia Supernova Remnants

TL;DR

This paper models the nonthermal continuum emissions from Type Ia supernova remnants during the Sedov-Taylor phase, using cosmic ray spectra from nonlinear shock acceleration simulations, and compares the results with observations.

Contribution

It introduces the Cosmicp code for calculating emissions from cosmic rays and provides new scalings and profiles for understanding SNR emissions across multiple wavelengths.

Findings

Electron emissions dominate radio to X-ray bands.

Pion decay mainly contributes to gamma-ray emissions.

Inverse Compton becomes significant in low-density ISM cases.

Abstract

We present calculations of expected continuum emissions from Sedov-Taylor phase Type Ia supernova remnants (SNRs), using the energy spectra of cosmic ray (CR) electrons and protons from nonlinear diffusive shock acceleration (DSA) simulations. A new, general-purpose radiative process code, Cosmicp, was employed to calculate the radiation expected from CR electrons and protons and their secondary products. These radio, X-ray and gamma-ray emissions are generally consistent with current observations of Type Ia SNRs. The emissions from electrons in these models dominate the radio through X-ray bands. Decays of \pi^0 s from p-p collisions mostly dominate the gamma-ray range, although for a hot, low density ISM case (n_{ISM}=0.003 cm^{-3}), the pion decay contribution is reduced sufficiently to reveal the inverse Compton contribution to TeV gamma-rays. In addition, we present simple scalings for the contributing emission processes to allow a crude exploration of model parameter space, enabling these results to be used more broadly. We also discuss the radial surface brightness profiles expected for these model SNRs in the X-ray and gamma-ray bands.