Comptonization by Reconnection Plasmoids in Black Hole Coronae II: Electron-Ion Plasma

Abstract

We perform two-dimensional particle-in-cell simulations of magnetic reconnection in electron-ion plasmas subject to strong Compton cooling and calculate the X-ray spectra produced by this process. The simulations are performed for trans-relativistic reconnection with magnetization $1\le \sigma \le 3$ (defined as the ratio of magnetic tension to plasma rest-mass density), which is expected in the coronae of accretion disks around black holes. We find that magnetic dissipation proceeds with inefficient energy exchange between the heated ions and the Compton-cooled electrons. As a result, most electrons are kept at a low temperature in Compton equilibrium with radiation, and so thermal Comptonization cannot reach photon energies $\sim 100$ keV observed from accreting black holes. Nevertheless, magnetic reconnection efficiently generates $\sim 100$ keV photons because of mildly relativistic bulk motions of the plasmoid chain formed in the reconnection layer. Comptonization by the plasmoid motions dominates the radiative output and controls the peak of the radiation spectrum $E_{\mathrm{pk}}$. We find $E_{\mathrm{pk}}\sim 40$ keV for $\sigma =1$ and $E_{\mathrm{pk}}\sim 100$ keV for $\sigma =3$. In addition to the X-ray peak around 100 keV, the simulations show a non-thermal MeV tail emitted by a non-thermal electron population generated near X-points of the reconnection layer. The results are consistent with the typical hard state of accreting black holes. In particular, we find that the spectrum of Cygnus~X-1 is well explained by electron-ion reconnection with $\sigma \sim 3$.

arXiv commentAccepted for publication in MNRAS: 16 pages, 15 figures, 1 table, 8 appendices. Part-I can be accessed at arXiv:2107.00263

References in corpus (48)

• Instability of current sheets and formation of plasmoid chains
• Fast Reconnection in High-Lundquist-Number Plasmas Due to Secondary Tearing Instabilities
• Magnetic fluctuation power near proton temperature anisotropy instability thresholds in the solar wind
• Fast magnetic reconnection in the plasmoid-dominated regime
• Relativistic Jets Shine through Shocks or Magnetic Reconnection?
• Radiative Processes, Spectral States and Variability of Black-Hole Binaries
• The corona contracts in a black-hole transient
• Black hole flares: ejection of accreted magnetic flux through 3D plasmoid-mediated reconnection
• Radiation Reaction Effects on Radiation Pressure Acceleration
• Magnetic Reconnection and Hot Spot Formation in Black Hole Accretion Disks
• The Soft Gamma-Ray Spectral Variability of Cygnus X-1
• Super-Eddington Accretion Disks around Supermassive black Holes
• Firehose and Mirror Instabilities in a Collisionless Shearing Plasma
• Non-thermal particle acceleration in collisionless relativistic electron-proton reconnection
• Shearing Box Simulations of the MRI in a Collisionless Plasma
• Plasmoids in relativistic reconnection, from birth to adulthood: first they grow, then they go
• Particle acceleration in axisymmetric pulsar current sheets
• Electron and Proton Acceleration in Trans-Relativistic Magnetic Reconnection: Dependence on Plasma Beta and Magnetization
• Probing the Inner Region of Cyg X-1 in the Low/Hard State through its X-ray Broad Band Spectrum
• A Review of the 0.1 Reconnection Rate Problem
• Accelerating AGN jets to parsec scales using general relativistic MHD simulations
• Electron and proton heating in trans-relativistic magnetic reconnection
• Radiative magnetic reconnection near accreting black holes
• Broad band spectrum of Cygnus X-1 in two spectral states with BeppoSAX
• PIC Simulations of Continuously Driven Mirror and Ion Cyclotron Instabilities in High Beta Astrophysical and Heliospheric Plasmas
• Disk, Corona, Jet Connection in the Intermediate State of MAXI J1820+070 Revealed by NICER Spectral-Timing Analysis
• The Steady Growth of the High-Energy Spectral Cutoff in Relativistic Magnetic Reconnection
• Relativistic Magnetic Reconnection in Electron-Positron-Proton Plasmas: Implications for Jets of Active Galactic Nuclei
• Fast particle acceleration in three-dimensional relativistic reconnection
• Electron Heating by the Ion Cyclotron Instability in Collisionless Accretion Flows. I. Compression-Driven Instabilities and the Electron Heating Mechanism
• Kinetic Simulations of Radiative Magnetic Reconnection in the Coronae of Accreting Black Holes
• Reconnection in Marginally Collisionless Accretion Disk Coronae
• Relativistic magnetic reconnection in collisionless ion-electron plasmas explored with particle-in-cell simulations
• Magnetic reconnection and plasmoid formation in three-dimensional accretion flows around black holes
• High-energy gamma-rays from Cyg X-1
• Particle acceleration in relativistic magnetic reconnection with strong inverse-Compton cooling in pair plasmas
• Secondary Energization in Compressing Plasmoids during Magnetic Reconnection
• Apar-T: code, validation, and physical interpretation of particle-in-cell results
• The energetics of relativistic magnetic reconnection: ion-electron repartition and particle distribution hardness
• Comptonization by Reconnection Plasmoids in Black Hole Coronae I: Magnetically Dominated Pair Plasma
• Emission of magnetar bursts and precursors of neutron star mergers
• Electron and Proton Heating in Transrelativistic Guide Field Reconnection
• Exploring the acceleration mechanisms for particle injection and power-law formation during trans-relativistic magnetic reconnection
• Evolution of the accretion disk-corona during bright hard-to-soft state transition: A reflection spectroscopic study with GX 339-4
• Production and persistence of extreme two-temperature plasmas in radiative relativistic turbulence
• PICsar: A 2.5D Axisymmetric, Relativistic, Electromagnetic, Particle in Cell Code with a Radiation Absorbing Boundary
• The Mechanism of Electron Injection and Acceleration in Trans-Relativistic Reconnection
• Non-ideal fields solve the injection problem in relativistic reconnection

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