Energy Partition in Relativistic Electron-Positron-Ion Reconnection

Le résumé fourni par la source

Relativistic magnetic reconnection, a prime mechanism for particle acceleration, has been extensively studied in electron--ion and pair plasmas, but how the dissipated energy is shared among species in electron--positron--ion plasmas, and in particular how ions are energized within a pair-dominated layer, remains poorly understood. We develop an analytic theory that couples single-particle orbit dynamics to the collective plasma response, and we validate it with particle-in-cell simulations spanning pair-dominated to electron--ion compositions. Particles are directly energized in electric-dominated regions until the reconnected magnetic field deflects them into the outflow; the characteristic escape length is in turn set by the relativistic skin depth of the reconnection-heated mixture, including the ion contribution. Writing $\sigmastar$ for the magnetic energy available per particle in units of $m_ec^2$ and $μ=m_i/m_e$, the mean lepton energy scales as $\sigmastar$, whereas the mean ion energy scales as $μ^{1/3}(\sigmastar)^{2/3}$ when ions escape non-relativistically from the electric-dominated regions and approaches the lepton energy when their escape is ultrarelativistic. The predicted energy fractions agree with simulations across composition, mass ratio, and magnetization. The ion share of the dissipated energy can fall far below the commonly assumed ion--lepton equipartition, reducing the energy available for hadronic and neutrino emission in reconnection-powered astrophysical sources.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.