Thermal equilibria of optically thin, magnetically supported, two-temperature, black hole accretion disks

H. Oda, Mami Machida, K. E. Nakamura, R. Matsumoto

Research output: Contribution to journalArticle

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Abstract

We obtained thermal equilibrium solutions for optically thin, two-temperature black hole accretion disks incorporating magnetic fields. The main objective of this study is to explain the bright/hard state observed during the bright/slow transition of galactic black hole candidates. We assume that the energy transfer from ions to electrons occurs via Coulomb collisions. Bremsstrahlung, synchrotron, and inverse Compton scattering are considered as the radiative cooling processes. In order to complete the set of basic equations, we specify the magnetic flux advection rate instead of β = p gas/p mag. We find magnetically supported (low-β), thermally stable solutions. In these solutions, the total amount of the heating via the dissipation of turbulent magnetic fields goes into electrons and balances the radiative cooling. The low-β solutions extend to high mass accretion rates (≳ α2MEdd) and the electron temperature is moderately cool (T e ∼ 108-10 9.5 K). High luminosities (≳0.1L Edd) and moderately high energy cutoffs in the X-ray spectrum (50-200 keV) observed in the bright/hard state can be explained by the low-β solutions.

Original languageEnglish
Pages (from-to)639-652
Number of pages14
JournalAstrophysical Journal
Volume712
Issue number1
DOIs
Publication statusPublished - Jan 1 2010
Externally publishedYes

Fingerprint

accretion disks
accretion
electron
magnetic field
cooling
Coulomb collisions
temperature
advection
magnetic fields
bremsstrahlung
energy
magnetic flux
dissipation
synchrotrons
electrons
cut-off
collision
energy transfer
luminosity
scattering

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Astronomy and Astrophysics
  • Nuclear and High Energy Physics

Cite this

Thermal equilibria of optically thin, magnetically supported, two-temperature, black hole accretion disks. / Oda, H.; Machida, Mami; Nakamura, K. E.; Matsumoto, R.

In: Astrophysical Journal, Vol. 712, No. 1, 01.01.2010, p. 639-652.

Research output: Contribution to journalArticle

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