Hadronic γ-ray images of Sedov supernova remnants

Abstract

A number of modern experiments in high‐energy astrophysics produce images of supernova remnants (SNRs) in the TeV and GeV γ‐rays. Either relativistic electrons (due to the inverse‐Compton scattering) or protons (due to the pion decays) may be responsible for this emission. In particular, the broad‐band spectra of SNRs may be explained in both leptonic and hadronic scenarios. Another kind of observational data, namely, images of SNRs, is an important part of experimental information. We present a method to model γ‐ray images of Sedov SNRs in uniform media and magnetic field due to hadronic emission. These γ‐rays are assumed to appear as a consequence of meson decays produced in inelastic collisions of accelerated protons with thermal protons downstream of the shock – a model would be relevant for SNRs without firm confirmations of the shock–cloud interaction, as e.g. SN 1006. Distribution of surface brightness of the shell‐like SNR is synthesized numerically for a number of configurations. An approximate analytical formula for azimuthal and radial variation of hadronic γ‐ray brightness close to the shock is derived. The properties of images as well as the main factors determining the surface brightness distribution are determined. Some conclusions that would be relevant to SN 1006 are discussed.

The effect of cosmic ray acceleration on supernova blast wave dynamics

“…In this work, we are studying magnetic obliquitydependent acceleration of protons at a strong, total energy conserving shock that is driven by a point explosion (similar in spirit to the analytic model by Beshley & Petruk 2012). Hence, our setup models the Sedov-Taylor phase of an expanding SNR and we examine how CR acceleration modifies its propagation depending on the upstream properties of the magnetic field.…”

Analytical-numerical methods of investigation of processes in the supernova remnants

“…Проте для певних наближень, наприклад для точкового вибуху без радіаційних втрат, що описує адіабатичне розширення в залишках наднових зір, це рівняння має аналітичний розв'язок. Для такого підходу ми побудували карти поверхневої яскравості, а також отримали наближені аналітичні формули для розрахунку профілів поверхневої яскравості для випромінювання як електронів, так і протонів [10,11].…”

Radio polarization maps of shell-type SNRs – II. Sedov models with evolution of turbulent magnetic field

“…As to the latter strategy to explore SNR images, a method to model the synchrotron radio and X-ray images of Sedov SNRs (that is the shell-like adiabatic remnant of a spherical explosion in a uniform medium) was developed by Fulbright & Reynolds (1990) and Reynolds (1998), who also analyzed the main features of the these maps. The method was adapted to the gamma-ray SNR images due to the inverse-Compton emission (Petruk et al 2009b(Petruk et al , 2011b and to those due to the hadronic interactions with protons inside SNR (Beshley & Petruk 2012). The method was generalized to the case of a SNR evolving in an ISM with nonuniform distributions of density and/or MF: the resulting asymmetries on the radio maps have been studied by Orlando et al (2007) and in X-rays and γ-rays by Orlando et al (2011).…”

“…Reynolds 1998); the energy losses due to pion production is neglected assuming that the shock is propagating in medium with density less than ∼ 10 4 cm −3 (e.g. Beshley & Petruk 2012). The evolution of pmax downstream is therefore given by pmax(a, t) pmax,s(ti) = ρ(a, t) ρs(ti)…”

“…The method was adapted to the gamma-ray SNR images due to the inverse-Compton emission (Petruk et al 2009b(Petruk et al , 2011b and to those due to the hadronic interactions with protons inside SNR (Beshley & Petruk 2012). The method was generalized to the case of a SNR evolving in an ISM with nonuniform distributions of density and/or MF: the resulting asymmetries on the radio maps have been studied by Orlando et al (2007) and in X-rays and γ-rays by Orlando et al (2011).…”