Production and persistence of extreme two-temperature plasmas in radiative relativistic turbulence

Abstract

Turbulence is a predominant process for energizing electrons and ions in collisionless astrophysical plasmas, and thus is responsible for shaping their radiative signatures (luminosity, spectra, and variability). To better understand the kinetic properties of a collisionless radiative plasma subject to externally driven turbulence, we investigate particle-in-cell simulations of relativistic plasma turbulence with external inverse Compton cooling acting on the electrons. We find that ions continuously heat up while electrons gradually cool down (due to the net effect of radiation), and hence the ion-to-electron temperature ratio $T_i/T_e$ grows in time. We show that $T_i/T_e$ is limited only by the size and duration of the simulations (reaching $T_i/T_e\sim 10^3$), indicating that there are no efficient collisionless mechanisms of electron-ion thermal coupling. This result has implications for models of radiatively inefficient accretion flows, such as observed in the Galactic Center and in M87, for which so-called two-temperature plasmas with $T_i/T_e\gg 1$ have been invoked to explain their low luminosity. Additionally, we find that electrons acquire a quasi-thermal distribution (dictated by the competition of turbulent particle energization and radiative cooling), while ions undergo efficient nonthermal acceleration (acquiring a harder distribution than in equivalent non-radiative simulations). There is a modest nonthermal population of high-energy electrons that are beamed intermittently in space, time, and direction; these beamed electrons may explain rapid flares in certain high-energy astrophysical systems (e.g., in the Galactic Center). These numerical results demonstrate that extreme two-temperature plasmas can be produced and maintained by relativistic radiative turbulence.

8 pages, 5 figures, submitted for publication

References in corpus (7)

• X-ray Properties of Black-Hole Binaries
• First M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring
• Kinetic turbulence in relativistic plasma: from thermal bath to non-thermal continuum
• Hybrid-Kinetic Simulations of Ion Heating in Alfvénic Turbulence
• Electron Heating by the Ion Cyclotron Instability in Collisionless Accretion Flows. I. Compression-Driven Instabilities and the Electron Heating Mechanism
• Electron Heating by the Ion Cyclotron Instability in Collisionless Accretion Flows. II. Electron Heating Efficiency as a Function of Flow Conditions
• The inverse-Compton X-ray-emitting lobes of the high-redshift giant radio galaxy 6C 0905+39

Cited by in corpus (17)

• Particle acceleration in strong MHD turbulence
• Pitch Angle Anisotropy Controls Particle Acceleration and Cooling in Radiative Relativistic Plasma Turbulence
• Comptonization by Reconnection Plasmoids in Black Hole Coronae I: Magnetically Dominated Pair Plasma
• Radiative Particle-in-Cell Simulations of Turbulent Comptonization in Magnetized Black-Hole Coronae
• Dynamic alignment and plasmoid formation in relativistic magnetohydrodynamic turbulence
• Comptonization by Reconnection Plasmoids in Black Hole Coronae II: Electron-Ion Plasma
• Turbulence and particle acceleration in a relativistic plasma
• Synchrotron Firehose Instability
• Spectra of magnetic turbulence in a relativistic plasma
• Spatial intermittency of particle distribution in relativistic plasma turbulence
• On the quadruple Beltrami fields in thermally relativistic electron-positron-ion plasma
• High-energy Emission from Turbulent Electron-ion Coronae of Accreting Black Holes
• Energy Diffusion and Advection Coefficients in Kinetic Simulations of Relativistic Plasma Turbulence
• PATOKA: Simulating Electromagnetic Observables of Black Hole Accretion
• Anisotropy and energy distribution of leptons and photons in radiative relativistic Alfvénic turbulence
• Fully kinetic shearing-box simulations of magnetorotational turbulence in 2D and 3D. I. Pair plasmas
• Effects of radiative losses on the relativistic jets of high-mass microquasars