The energetics of relativistic magnetic reconnection: ion-electron repartition and particle distribution hardness

Abstract

Collisionless magnetic reconnection is a prime candidate to account for flare-like or steady emission, outflow launching, or plasma heating, in a variety of high-energy astrophysical objects, including ones with relativistic ion-electron plasmas. But the fate of the initial magnetic energy in a reconnection event remains poorly known: what is the amount given to kinetic energy, the ion/electron repartition, and the hardness of the particle distributions? We explore these questions with 2D particle-in-cell simulations of ion-electron plasmas. We find that 45 to 75% of the total initial magnetic energy ends up in kinetic energy, this fraction increasing with the inflow magnetization. Depending on the guide field strength, ions get from 30 to 60% of the total kinetic energy. Particles can be separated into two populations that only weakly mix: (i) particles initially in the current sheet, heated by its initial tearing and subsequent contraction of the islands; and (ii) particles from the background plasma that primarily gain energy via the reconnection electric field when passing near the X-point. Particles (ii) tend to form a power-law with an index $p=-d\log n(\gamma )/d\log \gamma$, that depends mostly on the inflow Alfvén speed $V_A$ and magnetization ${\sigma }_s$ of species $s$, with for electrons $p=5$ to $1.2$ for increasing ${\sigma }_e$. The highest particle Lorentz factor, for ions or electrons, increases roughly linearly with time for all the relativistic simulations. This is faster, and the spectra can be harder, than for collisionless shock acceleration. We discuss applications to microquasar and AGN coronae, to extragalactic jets, and to radio lobes. We point out situations where effects such as Compton drag or pair creation are important.

15 pages, submitted to A&A

References in corpus (11)

• Fast TeV variability in blazars: jets in a jet
• Spectral and timing properties of a dissipative GRB photosphere
• The Role of the Guide Field in Relativistic Pair Plasma Reconnection
• Particle acceleration in the driven relativistic reconnection
• Reconnection in Marginally Collisionless Accretion Disk Coronae
• Did Swift measure GRB prompt emission radii?
• Jet contributions to the broad-band spectrum of Cyg X-1 in the hard state
• Relativistic magnetic reconnection in collisionless ion-electron plasmas explored with particle-in-cell simulations
• Implications of a PeV neutrino spectral cutoff in GRB models
• Observations of Magnetic Fields and Relativistic Beaming in Four Quasar Jets
• Particle-In-Cell Simulation of Electron Acceleration in Solar Coronal Jets

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