Global Electron Thermodynamics in Radiatively Inefficient Accretion Flows
In the collisionless plasmas of radiatively inefficient accretion flows, heating and acceleration of ions and electrons are not well understood. Recent studies in the gyrokinetic limit revealed the importance of incorporating both the compressive and Alfvénic cascades when calculating the partition...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acef12 |
| _version_ | 1797683378016747520 |
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| author | Kaushik Satapathy Dimitrios Psaltis Feryal Özel |
| author_facet | Kaushik Satapathy Dimitrios Psaltis Feryal Özel |
| author_sort | Kaushik Satapathy |
| collection | DOAJ |
| description | In the collisionless plasmas of radiatively inefficient accretion flows, heating and acceleration of ions and electrons are not well understood. Recent studies in the gyrokinetic limit revealed the importance of incorporating both the compressive and Alfvénic cascades when calculating the partition of dissipated energy between the plasma species. In this paper, we use a covariant analytic model of the accretion flow to explore the impact of compressive and Alfvénic heating, Coulomb collisions, compressional heating, and radiative cooling on the radial temperature profiles of ions and electrons. We show that, independent of the partition of heat between the plasma species, even a small fraction of turbulent energy dissipated to the electrons makes their temperature scale with a virial profile and the ion-to-electron temperature ratio smaller than in the case of pure Coulomb heating. In contrast, the presence of compressive cascades makes this ratio larger because compressive turbulent energy is channeled primarily into the ions. We calculate the ion-to-electron temperature in the inner accretion flow for a broad range of plasma properties, mass accretion rates, and black hole spins and show that it ranges between 5 ≲ T _i / T _e ≲ 40. We provide a physically motivated expression for this ratio that can be used to calculate observables from simulations of black hole accretion flows for a wide range of conditions. |
| first_indexed | 2024-03-12T00:13:33Z |
| format | Article |
| id | doaj.art-ed89d195f2d349ba841e839ad4fe2cda |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T00:13:33Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-ed89d195f2d349ba841e839ad4fe2cda2023-09-15T19:59:24ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195514710.3847/1538-4357/acef12Global Electron Thermodynamics in Radiatively Inefficient Accretion FlowsKaushik Satapathy0https://orcid.org/0000-0003-0433-3585Dimitrios Psaltis1https://orcid.org/0000-0003-1035-3240Feryal Özel2https://orcid.org/0000-0003-4413-1523Department of Physics, University of Arizona , 1118 E. Fourth Street, Tucson, AZ 85721, USA; School of Physics, Georgia Institute of Technology , 837 State St. NW, Atlanta, GA 30332, USASchool of Physics, Georgia Institute of Technology , 837 State St. NW, Atlanta, GA 30332, USASchool of Physics, Georgia Institute of Technology , 837 State St. NW, Atlanta, GA 30332, USAIn the collisionless plasmas of radiatively inefficient accretion flows, heating and acceleration of ions and electrons are not well understood. Recent studies in the gyrokinetic limit revealed the importance of incorporating both the compressive and Alfvénic cascades when calculating the partition of dissipated energy between the plasma species. In this paper, we use a covariant analytic model of the accretion flow to explore the impact of compressive and Alfvénic heating, Coulomb collisions, compressional heating, and radiative cooling on the radial temperature profiles of ions and electrons. We show that, independent of the partition of heat between the plasma species, even a small fraction of turbulent energy dissipated to the electrons makes their temperature scale with a virial profile and the ion-to-electron temperature ratio smaller than in the case of pure Coulomb heating. In contrast, the presence of compressive cascades makes this ratio larger because compressive turbulent energy is channeled primarily into the ions. We calculate the ion-to-electron temperature in the inner accretion flow for a broad range of plasma properties, mass accretion rates, and black hole spins and show that it ranges between 5 ≲ T _i / T _e ≲ 40. We provide a physically motivated expression for this ratio that can be used to calculate observables from simulations of black hole accretion flows for a wide range of conditions.https://doi.org/10.3847/1538-4357/acef12Black hole physicsAstrophysical black holesPlasma astrophysicsPlasma physics |
| spellingShingle | Kaushik Satapathy Dimitrios Psaltis Feryal Özel Global Electron Thermodynamics in Radiatively Inefficient Accretion Flows The Astrophysical Journal Black hole physics Astrophysical black holes Plasma astrophysics Plasma physics |
| title | Global Electron Thermodynamics in Radiatively Inefficient Accretion Flows |
| title_full | Global Electron Thermodynamics in Radiatively Inefficient Accretion Flows |
| title_fullStr | Global Electron Thermodynamics in Radiatively Inefficient Accretion Flows |
| title_full_unstemmed | Global Electron Thermodynamics in Radiatively Inefficient Accretion Flows |
| title_short | Global Electron Thermodynamics in Radiatively Inefficient Accretion Flows |
| title_sort | global electron thermodynamics in radiatively inefficient accretion flows |
| topic | Black hole physics Astrophysical black holes Plasma astrophysics Plasma physics |
| url | https://doi.org/10.3847/1538-4357/acef12 |
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