Two-body relaxation in relativistic thermal plasmas

Stepney, Susan

doi:10.1093/mnras/202.2.467

Cited by 87 publications

(62 citation statements)

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“…The energy transfer from ions to electrons is given by Stepney (1983) and is approximated for a two-temperature advectiondominated hot flow (Liu et al 2002) as…”

Section: Corona Dominated By Conductive Coolingmentioning

confidence: 99%

The Existence of Inner Cool Disks in the Low/Hard State of Accreting Black Holes

Liu

Taam

Meyer-Hofmeister

et al. 2007

ApJ

113

153

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The condensation of matter from a corona to a cool, optically thick inner disk is investigated for black hole X-ray transient systems in the low/ hard state. A description of a simple model for the exchange of energy and mass between corona and disk originating from thermal conduction is presented, taking into account the effect of Compton cooling of the corona by photons from the underlying disk. It is found that a weak, condensation-fed inner disk can be present in the low/hard state of black hole transient systems for a range of luminosities that depends on the magnitude of the viscosity parameter. For $ 0.1Y0.4, an inner disk can exist for luminosities in the range $(0.001Y0.02) L Edd . The model is applied to the X-ray observations of the black hole candidate sources GX 339À4 and SWIFT J1753.5À0127 in their low/ hard state. It is found that Compton cooling is important in the condensation process, leading to the maintenance of cool inner disks in both systems. As the results of the evaporation/condensation model are independent of the black hole mass, it is suggested that such inner cool disks may contribute to the optical and ultraviolet emission of low-luminosity active galactic nuclei.

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“…The energy transfer from ions to electrons is given by Stepney (1983) and is approximated for a two-temperature advectiondominated hot flow (Liu et al 2002) as…”

Section: Corona Dominated By Conductive Coolingmentioning

confidence: 99%

The Existence of Inner Cool Disks in the Low/Hard State of Accreting Black Holes

Liu

Taam

Meyer-Hofmeister

et al. 2007

ApJ

113

153

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“…Particle acceleration in the current sheet in the reconnection regions can lead to highly non-thermal particle distributions but, if the time scale of energy exchange through Coulomb collisions is shorter than the cooling timescale, thermalization of the electron distribution is achieved. The relaxation timescale for the electrons is given by (Spitzer 1967;Stepney 1983) (18) where ln Λ is the Coulomb logarithm. For the typical densities and temperatures of the problem at hand the value ln Λ = 13 is used.…”

Section: Thermalization Of the Electronsmentioning

confidence: 99%

Prompt emission spectra from the photosphere of a GRB

Giannios

2007

AIP Conference Proceedings

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Abstract. I explore the observational appearance of the photosphere of an ultrarelativistic flow with internal dissipation of energy ("dissipative" GRB model). As a case study, I use the magnetic reconnection model (AC model) that makes robust predictions on the energy dissipation rates at different radii in the flow. With analytical and numerical tools for the radiative transfer problem, I show that the flow develops a hot photosphere where inverse Compton scattering leads to highly non-thermal spectrum. For a wide range of luminosities and baryon loadings of the flow, this spectrum is very close to the observed prompt GRB emission. Its luminosity ranges from ∼ 3 to 20% of that of the total energy input.

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“…For a sufficiently low electron temperature, electrons and ions become thermally coupled. The rate of collisional energy transfer from ions to electrons given by Stepney (1983), is approximated (Liu et al 2002) as where T e , T i are the electron and ion temperatures, and n e , n i are the electron and ion number densities. This energy transfer increases with decreasing electron temperature.…”

Section: The Two-temperature Adaf-type Corona In the Inner Regionmentioning

confidence: 99%

Coronae above accretion disks around black holes: the effect of Compton cooling

Meyer-Hofmeister

Liu

Meyer

2012

A&A

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Context. The geometry of the accretion flow around stellar mass and supermassive black holes depends on the accretion rate. Broad iron emission lines originating from the irradiation of cool matter can indicate that there is an inner disk below a hot coronal flow. Aims. These emission lines have been detected in X-ray binaries. Observations with the Chandra X-ray Observatory, XMM Newton, and Suzaku have confirmed the presence of these emission lines also in a large fraction of Seyfert-1 active galactic nuclei (AGN). We investigate the accretion flow geometry for which broad iron emission lines can arise in hard and soft spectral states. Methods. We study an ADAF-type coronal flow, where the ions are viscously heated and electrons receive their heat only by collisions from the ions and are Compton cooled by photons from an underlying cool disk. Results. For a strong mass flow in the disk and the resulting strong Compton cooling only a very weak coronal flow is possible. This limitation allows the formation of ADAF-type coronae above weak inner disks in the hard state, but almost rules them out in the soft state. Conclusions. The observed hard X-ray luminosity in the soft state, of up to 10% or more of the total flux, indicates that there is a heating process that directly accelerates the electrons. This might point to the action of magnetic flares of disk magnetic fields reaching into the corona. Such flares have also been proposed by observations of the spectra of X-ray black hole binaries without a thermal cut-off around 200 keV.

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Two-body relaxation in relativistic thermal plasmas

Cited by 87 publications

References 0 publications

The Existence of Inner Cool Disks in the Low/Hard State of Accreting Black Holes

The Existence of Inner Cool Disks in the Low/Hard State of Accreting Black Holes

Prompt emission spectra from the photosphere of a GRB

Coronae above accretion disks around black holes: the effect of Compton cooling

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