Temperature properties in magnetised and radiatively cooled two-temperature accretion flows onto a black hole

Abstract

Simplified assumptions about the thermodynamics of the electrons are normally employed in general-relativistic magnetohydrodynamic (GRMHD) simulations of accretion onto black holes. To counter this, we have developed a self-consistent approach to study magnetised and radiatively cooled two-temperature accretion flows around a Kerr black hole in two spatial dimensions. The approach includes several heating processes, radiative cooling, and a coupling between the electrons and the ions via Coulomb interaction. We test our approach by performing axisymmetric GRMHD simulations of magnetised tori accreting onto a Kerr black hole under various astrophysical scenarios. In this way, we find that the inclusion of the Coulomb interaction and the radiative cooling impacts the thermodynamical properties of both the ions and electrons, changing significantly the temperature distribution of the latter, and underlining the importance of a two-temperature approach when imaging these flows. In addition, we find that the accretion rate influences the bulk properties of the flow as well as the thermodynamics of the electrons and ions. Interestingly, we observe qualitatively distinct temperature properties for SANE and MAD accretion modes while maintaining the same accretion rates, which could help distinguishing MAD and SANE accretion flows via observations. Finally, we propose two new relations for the temperature ratios of the electrons, ions, and of the gas in terms of the plasma-$\beta$ parameter. The new relations represent a simple and effective approach to treat two-temperature accretion flows on supermassive black holes such as Sgr A* and M\,87*.

13 pages, 8 figures, accepted for publication at MNRAS

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Cited by in corpus (9)

• First M87 Event Horizon Telescope Results. IX. Detection of Near-horizon Circular Polarization
• Microphysical Plasma Relations from Special-relativistic Turbulence
• Two-Temperature GRMHD Simulations of Black Hole Accretion Flows with Multiple Magnetic Loops
• Survey of Radiative, Two-Temperature Magnetically Arrested Simulations of the Black Hole M87* I: Turbulent Electron Heating
• Illuminating Black Hole Shadow with Dark Matter Annihilation
• Non-thermal Synchrotron Emission and Polarization Signatures during Black Hole Flux Eruptions
• Radiative Cooling Effects on Plasmoid Formation in Black Hole Accretion Flows with Multiple Magnetic Loops
• Impacts of radiative cooling on the images of a black hole shadow and extended jets in two-temperature GRMHD simulations
• Parameter Inference of Black Hole Images using Deep Learning in Visibility Space