3D simulations of the emission from young supernova remnants including particle acceleration
September 10, 2012
Abstract: Supernova remnants are believed to be the major contributors to Galactic cosmic rays, but direct evidence for highly energetic (PeV) protons in these objects remains elusive. In the last few years, a new generation of gamma-ray instruments (Fermi, Agile, H.E.S.S., VERITAS, MAGIC) has detected non-thermal emission from SNRs at very high energies (from the GeV to the TeV), but it is still difficult to disentangle the hadronic and leptonic contributions (a recent census of high-energy observations of all Galactic SNRs can be found at www.physics.umanitoba.ca/snr/SNRcat). However, if protons are efficiently accelerated at the blast wave, this should impact the dynamics of the SNR, and therefore its morphological and spectral evolution. Evidence for modified shocks has been recently obtained with the Chandra and XMM-Newton satellites, in young remnants such as Tycho and SN 1006. In this talk, I will show how these effects can be investigated by the means of numerical simulations. The code developed couples the hydrodynamical evolution of the SNR with a non-linear kinetic model of diffusive shock acceleration. At a given age, is computed a posteriori: 1/ the non-equilibrium ionization state of the plasma and its thermal radiation (continuum and lines), and 2/ the transport of particles inside the SNR and their non-thermal emission (synchrotron, inverse Compton, pion decay). The emission is integrated along the line of sight to produce maps that can be compared with observations. I will show 1/ the impact of particle acceleration on the thermal X-ray emission of the SNR through modifications of the shock structure and conditions, and 2/ the dependence of the non-thermal radio to gamma-ray emission of the SNR on a possible amplification of the magnetic field by the particles themselves. These two points provide indirect diagnostics of the presence of energetic protons.