Abstract

Contributed Talk - Splinter SNR

Thursday, 12 September 2024, 14:30   (S14)

Young supernova remnants interacting with dense CSM

Robert Brose, Iurii Sushch, Jonathan Mackey
Dublin City University

Supernova remnants are known to accelerate cosmic rays from the detection of non-thermal emission of radio waves, X-rays, and gamma rays. The presence of cut-offs in the gamma-ray spectra of several young SNRs led to the idea that the highest energies might only be achieved during the very initial stages of a remnant’s evolution. The gamma-ray luminosity is assumed to peak in the first weeks after the Supernova explosion where strong γγ-absorption attenuates the observable signal. Here, we investigate to which extent the interaction of SNR-shocks with dense circumstellar material (CSM) and structures in the CSM around luminous blue variable (LBV) stars and red supergiants (RSGs) affects the cosmic-ray production and the multiwavelength emission from radio to gamma-ray energies of these remnants. We use the time-dependent acceleration code RATPaC to study the acceleration of cosmic rays in supernovae expanding into dense environments around massive stars. We performed spherically symmetric 1-D simulations in which we simultaneously solve the transport equations for cosmic rays, magnetic turbulence, and the hydrodynamical flow of the thermal plasma in the test-particle limit. We investigated typical parameters of the CSM in the freely expanding winds around LBV and RSG stars and additionally added dense structures that arise from episodes of highly-enhanced mass-loss of the progenitors or photoionization shells formed by the interaction of dense winds with the intense photon fields in typical cluster environments. We find that typical “smooth” winds provide insufficient conditions to accelerate CRs to the highest energies. However interactions with the dense structures up to a few months after the explosion boost the maximal achievable proton energy beyond a PeV. At this stage, the γγ-absorption by photons emitted from the Supernova’s photosphere becomes negligible. The interaction with the dense material triggers a (re)-brightening of the remnant in radio, optical and thermal X-rays, which can be used to trigger pointed gamma-ray observations, that are needed to understand the ongoing particle acceleration.