Speaker
Description
Supernova remnants (SNRs) are generally considered as the main contributors to the Galactic sea of cosmic rays (CRs) on the account of their energy budget. Indeed, they are the only known sources in the Galaxy that are capable of explaining the energy density of CRs at lowest energies. Acceleration of CRs at the shock fronts of SNRs is confirmed by detection of non-thermal emission of radio waves, X-rays, and gamma rays. It is, however, unclear what are the highest energies that can be reached in these objects. There are several reasons to believe that SNRs are the most efficient accelerators during the very initial stages of evolution, right after the explosion, but so far no supernovae (SNe) were detected in gamma-rays despite dedicated observational campaigns. This could be partially due to the observation strategy - the peak of gamma-ray emission for core-collapse (CC) SNe evolving in smooth winds is expected to happen days to weeks after the explosion where most of the emission is attenuated by gamma-gamma interactions with a photosphere. It is known, however, that massive stars such as luminous blue variable (LBV) stars and red supergiants (RSGs) feature circumstellar shells with enhanced density. Interaction of the SN shock with such shells would increase both acceleration efficiency and non-thermal emission. Such episodes of interaction may happen months or years after the explosion where gamma-gamma absorption by photosphere is negligible and gamma-ray emission can be well detectable. In this talk we present numeric simulations of such scenarios and show that current observation strategies for gamma-ray signals from SNe should be re-designed. We propose the multiwavelength observation campaign for transient emission from interacting SNe and report on the status of observational proposals submitted to various instruments. At the time of the abstract submission the campaign already resulted in detection of the radio re-brightening of a supernova 18 years after explosion.
