Dynamical energy dissipation of relativistic magnetic bullets

Abstract

ABSTRACT To demonstrate the magnetic energy dissipation via relativistic shocks, we carry out spherically symmetrical one-dimensional special relativistic magnetohydrodynamic simulations of highly magnetized outflows with an adaptive mesh refinement method. We first investigate the details of the dynamical energy dissipation via interaction between a single ejecta and an external medium. The energy dissipation time-scales, which affect the early behaviour of the afterglow emission in gamma-ray bursts, are estimated for a wide range of magnetization. In addition, we demonstrate the internal shock dissipation in multiple interactions between magnetically dominated relativistic ejecta and kinetically dominated non-relativistic winds. Our numerical results show that ∼10 per cent of the magnetic energy in the ejecta can be converted into the thermal energy of the relativistic and low-magnetized outflows via shocks in the rarefaction waves or the winds. Such hot and less magnetized outflows are relevant for observed non-thermal emissions in blazars or gamma-ray bursts.