Electron Heating in the Trans-Relativistic Perpendicular Shocks of Tilted Accretion Flows

Abstract

General relativistic magnetohydrodynamic (GRMHD) simulations of black hole tilted disks -- where the angular momentum of the accretion flow at large distances is misaligned with respect to the black hole spin -- commonly display standing shocks, within a few to tens of gravitational radii from the black hole. In GRMHD simulations of geometrically thick, optically thin accretion flows, applicable to low-luminosity sources like Sgr A* and M87*, the shocks have trans-relativistic speed, moderate plasma beta (the ratio of ion thermal pressure to magnetic pressure is ${\beta }_{pi1}\sim 1-8$), and low sonic Mach number (the ratio of shock speed to sound speed is $M_s\sim 1-5$). We study such shocks with two-dimensional particle-in-cell simulations and we quantify the efficiency and mechanisms of electron heating, for the special case of pre-shock magnetic fields perpendicular to the shock direction of propagation. We find that the post-shock electron temperature $T_{e2}$ exceeds the adiabatic expectation $T_{e2,\mathrm{ad}}$ by an amount $T_{e2}/T_{e2,\mathrm{ad}}-1\simeq 0.0016M_s^{3.6}$, nearly independent of the plasma beta and of the pre-shock electron-to-ion temperature ratio $T_{e1}/T_{i1}$, which we vary from $0.1$ to unity. We investigate the heating physics for $M_s\sim 5-6$ and find that electron super-adiabatic heating is governed by magnetic pumping at $T_{e1}/T_{i1}=1$, whereas heating by $B$-parallel electric fields (i.e., parallel to the local magnetic field) dominates at $T_{e1}/T_{i1}=0.1$. Our results provide physically-motivated subgrid prescriptions for electron heating at the collisionless shocks seen in GRMHD simulations of black hole accretion flows.

12 pages, 7 figures, 1 table; submitted

References in corpus (28)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• Global General Relativistic MHD Simulation of a Tilted Black-Hole Accretion Disk
• Alignment of Magnetized Accretion Disks and Relativistic Jets with Spinning Black Holes
• Electron and proton heating in trans-relativistic magnetic reconnection
• Hybrid-Kinetic Simulations of Ion Heating in Alfvénic Turbulence
• Epicyclic Motions and Standing Shocks in Numerically Simulated Tilted Black-Hole Accretion Disks
• Ion and Electron Acceleration in Fully Kinetic Plasma Turbulence
• Tilted Disks around Black Holes: A Numerical Parameter Survey for Spin and Inclination Angle
• Conservative GRMHD Simulations of Moderately Thin, Tilted Accretion Disks
• Electron and Proton Heating in Transrelativistic Guide Field Reconnection
• Electron-Ion Temperature Ratio in Astrophysical Shocks
• No Evidence for Bardeen-Petterson Alignment in GRMHD Simulations and Semi-Analytic Models of Moderately Thin, Prograde, Tilted Accretion Disks
• Radiation Transport Two-Temperature GRMHD Simulations of Warped Accretion Disks
• Electron Heating in Low Mach Number Perpendicular shocks. I. Heating Mechanism
• Nozzle Shocks, Disk Tearing and Streamers Drive Rapid Accretion in 3D GRMHD Simulations of Warped Thin Disks
• Disk Tearing Leads to Low and High Frequency Quasi Periodic Oscillations in a GRMHD Simulation of a Thin Accretion Disk
• Effects of Multi-scale Plasma Waves on Electron Preacceleration at Weak Quasi-perpendicular Intracluster Shocks
• Particle energization in relativistic plasma turbulence: solenoidal versus compressive driving
• Rotation in Event Horizon Telescope Movies
• Effect of geometrically thin discs on precessing, thick flows: Relevance to type-C QPOs
• Nonlinear resonant torus oscillations as a model of Keplerian disc warp dynamics
• A Heating Mechanism via Magnetic Pumping in the Intracluster Medium
• Microinstabilities in the Transition Region of Weak Quasi-Perpendicular Intracluster Shocks
• Self-gravitating disks around rapidly spinning, tilted black holes: General relativistic simulations
• The Effects of Tilt on the Time Variability of Millimeter and Infrared Emission from Sagittarius A*
• Electron Heating in 2D Particle-in-Cell Simulations of Quasi-Perpendicular Low-Beta Shocks

Cited by in corpus (3)

• High-energy Emission from Turbulent Electron-ion Coronae of Accreting Black Holes
• Extreme scale height variations and nozzle shocks in warped disks
• Tilted Accretion Disks