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Beloborodov, V. L.; Rodionov, A. P.; Вититнова, М. Б.; Zalesskaya, M. A.; Крыжановский, С. А.; Tyukavkina, N. A.; Kaverina, N. A.

doi:10.1023/a:1012333402436

Cited by 3 publications

(4 citation statements)

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“…Czerny & Elvis (1987) have shown that the models which account for the electron scattering of the accretion disk photons are better than the simple 'sum of blackbodies' model. Similar thermal Comptonization models have been worked out by Lightman & Zdziarski (1987); Coppi (1992); Haardt (1993); Coppi (1999) and Beloborodov (1999) among others.…”

Section: Comptonisation By ∼ 150 Ev Plasmamentioning

confidence: 61%

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The influence of soft spectral components on the structure and stability of warm absorbers in active galactic nuclei

Chakravorty¹,

Misra²,

Elvis³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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The radiation from the central regions of active galactic nuclei, including that from the accretion disc surrounding the black hole, is likely to peak in the extreme-ultraviolet ∼13-100 eV. However, due to Galactic absorption, we are limited to constrain the physical properties, i.e. the black hole mass and the accretion rate, from what observations we have below ∼10 eV or above ∼100 eV. In this paper, we predict the thermal and ionization states of warm absorbers as a function of the shape of the unobservable continuum. In particular we model an accretion disc at kT in ∼ 10 eV and a soft excess at kT se ∼ 150 eV. The warm absorber, which is the highly ionized gas along the line of sight to the continuum, shows signatures in the ∼0.3-2 keV energy range consisting of numerous absorption lines and edges of various ions, some of the prominent ones being H-and He-like oxygen, neon, magnesium and silicon. We find that the properties of the warm absorber are significantly influenced by the changes in the temperature of the accretion disc, as well as by the strength of the soft excess, as they affect the optical depth particularly for iron and oxygen. These trends may help develop a method of characterizing the shape of the unobservable continuum and the occurrence of warm absorbers.

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Section: Comptonisation By ∼ 150 Ev Plasmamentioning

confidence: 61%

“…by the Compton y-parameter (Rybicki & Lightman 1986). Beloborodov (1999) had shown that there is a simple relation Γc ≈ 9 4 y −2/9 between the power-law index and the Compton y-parameter. Thus, in our model, Γc, used as an input, gives a measure of the extent of Compton reprocessing; i.e.…”

Section: Comptonisation By ∼ 150 Ev Plasmamentioning

confidence: 99%

The influence of soft spectral components on the structure and stability of warm absorbers in active galactic nuclei

Chakravorty¹,

Misra²,

Elvis³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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“…The hydrodynamic equations of a relativistic disk express conservation of baryon number, energy, and momentum (angular and radial) in Kerr spacetime (see Beloborodov 1999 for a review). Hereafter we use Boyer-Lindquist coordinates x α = (t, r, θ, φ) with the corresponding Kerr metric g αβ , which has two parameters: the black hole mass M and its dimensionless spin parameter 0 < a < 1 (see e.g.…”

Section: One-dimensional Relativistic Hydrodynamicsmentioning

confidence: 99%

Neutrino‐cooled Accretion Disks around Spinning Black Holes

Chen

Beloborodov

2007

ApJ

334

458

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We calculate the structure of accretion disks around Kerr black holes for accretion ratesṀ = 0.001−10M ⊙ s −1 . Such high-Ṁ disks are plausible candidates for the central engine of gamma-ray bursts. Our disk model is fully relativistic and treats accurately microphysics of the accreting matter: neutrino emissivity, opacity, electron degeneracy, and nuclear composition. The neutrino-cooled disk forms above a critical accretion rateṀ ign that depends on the black hole spin. The disk has the "ignition" radius r ign where neutrino flux rises dramatically, cooling becomes efficient, and the proton-to-nucleon ratio Y e drops. Other characteristic radii are r α where most of α-particles are disintegrated, r ν where the disk becomes ν-opaque, and r tr where neutrinos get trapped and advected into the black hole. We find r α , r ign , r ν , r tr and show their dependence onṀ . We discuss the qualitative picture of accretion and present sample numerical models of the disk structure. All neutrino-cooled disks regulate themselves to a characteristic state such that: (1) electrons are mildly degenerate, (2) Y e ∼ 0.1, and (3) neutrons dominate the pressure in the disk.

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“…Many authors think that the quasars and Seyfert galaxies have an accretion disk; set θ(0 ≤ θ ≤ π/2) the angle between the axis of the disk and the line of sight to the Earth. The physics of the disks is very complex [23]; the star and the disk can produce X rays whose absorption by the disk [17,18,19] is observed for θ ≈ π/2.…”

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confidence: 99%

Propagation of light in low-pressure ionized and atomic hydrogen: application to astrophysics

Moret-Bailly

2003

IEEE Trans. Plasma Sci.

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Impulsive Stimulated Raman Scattering"(ISRS) uses ultra-short laser pulses to shift light frequencies; the frequency shift depends on the power of the laser pulses because this power is very large. The relative frequency shifts of "Coherent Raman Effect on Incoherent Light"(CREIL) described in this paper are independent on the intensity of the ordinary incoherent light that it uses, and, in a first approximation, on the frequency of the light. Since CREIL does not blur images or alter the spectral pattern, CREIL effect may be confused with Doppler frequency shifts. ISRS and CREIL are parametric effects that do not excite matter, they transfer energy from "hot beams"to "cold beams". These transfers correspond to spectral shifts; in CREIL thermal radiation is blue-shifted, that is heated.CREIL requires low pressure gases acting as catalysts. These gases must have Raman transitions in the radio frequencies range: for example H + 2 or excited atomic hydrogen in a magnetic field. The spectral lines resulting from a simultaneous absorption (or emission) and CREIL have a width at least equal to the frequency shift, so that the lines of a complex spectrum may be weakened and mixed, becoming nearly invisible.In interstellar space, molecular hydrogen is ionised, but since H + 2 is quickly destroyed by collisions it persists only at pressures low enough to provide CREIL; the redshift widens the weak absorption lines of H + 2 which becomes undetectable. It contributes to the "cosmological redshift"and amplification of the microwave 2.7K background radiation.Using only well established physics and normal astronomical objects, CREIL provides a plausible explanation for the enigmatic spectra of the quasars.

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Cited by 3 publications

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The influence of soft spectral components on the structure and stability of warm absorbers in active galactic nuclei

The influence of soft spectral components on the structure and stability of warm absorbers in active galactic nuclei

Neutrino‐cooled Accretion Disks around Spinning Black Holes

Propagation of light in low-pressure ionized and atomic hydrogen: application to astrophysics

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