High-Energy Emission from Interacting Supernovae: New Constraints on Cosmic-Ray Acceleration in Dense Circumstellar Environments

TL;DR

This paper models high-energy emissions from interacting supernovae, providing new constraints on cosmic-ray acceleration in dense environments through comprehensive multi-wavelength and neutrino predictions, applied to specific supernovae data.

Contribution

It introduces a new time-dependent model for non-thermal emission from supernovae interacting with dense circumstellar material, including electromagnetic cascades and attenuation effects.

Findings

Constraints on cosmic-ray energy fraction <0.05-0.1 from SN 2010jl data

Radio observations are consistent with the model

Model predicts detectable gamma-ray and neutrino signals

Abstract

Supernovae (SNe) with strong interactions with circumstellar material (CSM) are promising candidate sources of high-energy neutrinos and gamma rays, and have been suggested as an important contributor to Galactic cosmic rays beyond 1 PeV. Taking into account the shock dissipation by a fast velocity component of SN ejecta, we present comprehensive calculations of the non-thermal emission from SNe powered by shock interactions with a dense wind or CSM. Remarkably, we consider electromagnetic cascades in the radiation zone and subsequent attenuation in the pre-shock CSM. A new time-dependent phenomenological prescription provided by this work enables us to calculate gamma-ray, hard X-ray, radio, and neutrino signals, which originate from cosmic rays accelerated by the diffusive shock acceleration mechanism. We apply our results to SN IIn 2010jl and SN Ib/IIn 2014C, for which the model parameters can be determined from the multi-wavelength data. For SN 2010jl, the more promising case, by using the the latest Fermi Large Area Telescope (LAT) Pass 8 data release, we derive new constraints on the cosmic-ray energy fraction, <0.05-0.1. We also find that the late-time radio data of these interacting SNe are consistent with our model. Further multi-messenger and multi-wavelength observations of nearby interacting SNe should give us new insights into the diffusive shock acceleration in dense environments as well as pre-SN mass-loss mechanisms.