Kinetic simulations of relativistic magnetic reconnection with synchrotron and inverse Compton cooling

Abstract

First results are presented from kinetic numerical simulations of relativistic collisionless magnetic reconnection in a pair plasma that include radiation reaction from both synchrotron and inverse Compton (IC) processes, motivated by non-thermal high-energy astrophysical sources, including in particular blazars. These simulations are initiated from a configuration known as ‘ABC fields’ that evolves due to coalescence instability and generates thin current layers in its linear phase. Global radiative efficiencies, instability growth rates, time-dependent radiation spectra, lightcurves, variability statistics and the structure of current layers are investigated for a broad range of initial parameters. We find that the IC radiative signatures are generally similar to the synchrotron signatures. The luminosity ratio of IC to synchrotron spectral components, the Compton dominance, can be modified by more than one order of magnitude with respect to its nominal value. For very short cooling lengths, we find evidence for modification of the temperature profile across the current layers, no systematic compression of plasma density and very consistent profiles of the scalar product$\boldsymbol{E}\boldsymbol{\cdot }\boldsymbol{B}$of electric field$\boldsymbol{E}$and magnetic field$\boldsymbol{B}$. We decompose the profiles of$\boldsymbol{E}\boldsymbol{\cdot }\boldsymbol{B}$with the use of the Vlasov momentum equation, demonstrating a contribution from radiation reaction at the thickness scale consistent with the temperature profile.