Spectra from a Magnetic Reconnection–heated Corona in Active Galactic Nuclei

Liu, B. F.; Mineshige, Shin; Ohsuga, Ken

doi:10.1086/368282

Cited by 75 publications

(109 citation statements)

References 33 publications

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“…Therefore, we conclude that the disk emission relative to the corona emission increases with increasingṁ. This is in agreement with some models of corona with a slab geometry (e.g., Czerny et al 1997;Janiuk & Czerny 2000;Merloni & Fabian 2002;Liu et al 2003), where the ox -ṁ correlation arises due to a dependency of the size of the corona onṁ.…”

Section: Dependence Of Ox Onṁsupporting

confidence: 91%

“…Some theoretical models have suggested that the fraction of bolometric luminosity emitted by the disk should depend onṁ, but be relatively insensitive to M BH (e.g., Czerny et al 2003;Liu et al 2003). Therefore, while a significant dependence of f D on M BH is not predicted by these disk/corona models, these models are still consistent with the interpretation that a M BH -ṁ correlation is driving the steeper ox -M BH correlation.…”

Section: Dependence Of Ox On M Bhmentioning

confidence: 63%

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Observational Constraints on the Dependence of Radio‐Quiet Quasar X‐Ray Emission on Black Hole Mass and Accretion Rate

Kelly

Bechtold

Trump

et al. 2008

ASTROPHYS J SUPPL S

126

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In this work we use a sample of 318 radio-quiet quasars (RQQs) to investigate the dependence of the ratio of optical/UV flux to X-ray flux, ox , and the X-ray photon index, À X , on black hole mass, UV relative to Eddington luminosity, and X-ray relative to Eddington luminosity. Our sample is drawn from the literature, with X-ray data from ROSAT and Chandra, and optical data mostly from the SDSS; 153 of these sources have estimates of À X from Chandra. We estimate M BH using standard estimates derived from the H, Mg ii, and C iv broad emission lines. Our sample spans a broad range in black hole mass (10 6 P M BH /M P 10 10 ), redshift (0 < z < 4:8), and luminosity (10 43 P kL k (2500 8)½ergs s À1 P 10 48 ). We find that ox increases with increasing M BH and L UV /L Edd and decreases with increasing L X /L Edd . In addition, we confirm the correlation seen in previous studies between À X and M BH and both L UV /L Edd and L X /L Edd ; however, we also find evidence that the dependence of À X of these quantities is not monotonic, changing sign at M BH $ 3 ; 10 8 M . We argue that the ox correlations imply that the fraction of bolometric luminosity emitted by the accretion disk, as compared to the corona, increases with increasing accretion rate relative to the Eddington rate,ṁ. In addition, we argue that the À X trends are caused by a dependence of X-ray spectral index onṁ. We discuss our results within the context of accretion models with Comptonizing corona and discuss the implications of the ox correlations for quasar feedback. To date, this is the largest study of the dependence of RQQ X-ray parameters on black hole mass and related quantities, and the first to attempt to correct for the large statistical uncertainty in the broad-line mass estimates.

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Section: Dependence Of Ox Onṁsupporting

confidence: 91%

Section: Dependence Of Ox On M Bhmentioning

confidence: 63%

Observational Constraints on the Dependence of Radio‐Quiet Quasar X‐Ray Emission on Black Hole Mass and Accretion Rate

Kelly

Bechtold

Trump

et al. 2008

ASTROPHYS J SUPPL S

126

View full text Add to dashboard Cite

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“…Specifically, for a corona in the form of a slab lying above the disk, nearly half the total coronal emission impinges on the optically thick disk and is reprocessed as blackbody radiation (Haardt & Maraschi 1991;Liu et al 2003). The luminosity associated with this irradiation is close to the observed luminosity.…”

Section: Discussionmentioning

confidence: 74%

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

Liu

Taam

Meyer-Hofmeister

et al. 2007

ApJ

Self Cite

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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“…It has been found that the temperature of the hot electrons in the corona is roughly around 10 9 K, which can successfully reproduce a power-law hard X-ray spectrum as observed (e.g., Liu et al 2003;Cao 2009). In this work, we consider a hot corona above a thin accretion disk, which is a reservoir supplying hot gas to feed the outflow driven by the magnetic field and radiation force of the disk.…”

Section: Boundary Conditionsmentioning

confidence: 86%

The Outflows Accelerated by the Magnetic Fields and Radiation Force of Accretion Disks

Cao¹

2014

ApJ

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The inner region of a luminous accretion disk is radiation-pressure-dominated. We estimate the surface temperature of a radiation-pressure-dominated accretion disk, Θ = c 2 s /r 2 Ω 2 K (H/r) 2 , which is significantly lower than that of a gas-pressure-dominated disk, Θ ∼ (H/r) 2 . This means that the outflow can be launched magnetically from the photosphere of the radiation-pressure-dominated disk only if the effective potential barrier along the magnetic field line is extremely shallow or no potential barrier is present. For the latter case, the slow sonic point in the outflow will probably be in the disk, which leads to a slow circular dense flow above the disk. This implies that hot gas (probably in the corona) is necessary for launching an outflow from the radiation-pressure-dominated disk, which provides a natural explanation for the observational evidence that the relativistic jets are related to hot plasma in some X-ray binaries and active galactic nuclei. We investigate the outflows accelerated from the hot corona above the disk by the magnetic field and radiation force of the accretion disk. We find that with the help of the radiation force, the mass loss rate in the outflow is high, which leads to a slow outflow. This may be why the jets in radio-loud narrow-line Seyfert galaxies are in general mildly relativistic compared with those in blazars.

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Spectra from a Magnetic Reconnection–heated Corona in Active Galactic Nuclei

Cited by 75 publications

References 33 publications

Observational Constraints on the Dependence of Radio‐Quiet Quasar X‐Ray Emission on Black Hole Mass and Accretion Rate

Observational Constraints on the Dependence of Radio‐Quiet Quasar X‐Ray Emission on Black Hole Mass and Accretion Rate

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

The Outflows Accelerated by the Magnetic Fields and Radiation Force of Accretion Disks

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