On the dynamics of clouds in the broad-line region of AGNs with an ADAF atmosphere

Khajenabi, Fazeleh

doi:10.1093/mnras/stu2193

Cited by 11 publications

(19 citation statements)

References 27 publications

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“…The Eddington ratio is denoted by l = La/L edd where La and L edd are the luminosity of the central source and the Eddington luminosity, respectively. In the absence of drag force, the above equations reduce to the main equations of the previous studies (e.g., Plewa et al 2013;Khajenabi 2015). We note that in our model each cloud is in pressure equilibrium with the ambient gas.…”

Section: General Formulationmentioning

confidence: 55%

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On the orbital motion of cold clouds in broad-line regions

Shadmehri

2015

Mon. Not. R. Astron. Soc.

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We study orbit of a pressure-confined cloud in the broad-line region (BLR) of active galactic nuclei (AGNs) when the combined effects of the central gravity and anisotropic radiation pressure and the drag force are considered. Physical properties of the intercloud gas such as its pressure and dynamic viscosity are defined as power-law functions of the radial distance. For a drag force proportional to the relative velocity of a cloud and the background gas, a detailed analysis of the orbits is performed for different values of the input parameters. We also present analytical solutions for a situation where the intercloud pressure is uniform and the viscosity is proportional to the inverse square of the radial distance. Our analytical and numerical solutions demonstrate decay of the orbits because of considering the drag force so that a cloud will eventually fall onto the central region after so called time-of-flight. We found that time-of-flight of a BLR cloud is proportional to the inverse of the dimensionless drag coefficient. We discuss if time-of-flight becomes shorter than the life time of the whole system, then existence of mechanisms for continually forming BLR clouds is needed.

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Section: General Formulationmentioning

confidence: 55%

“…BLR clouds are subject to the anisotropic radiation pressure of a central source as has been pointed out by Liu & Zhang (2011). Recently, a few authors studied orbit of BLR clouds under combined effects of the central gravity and anisotropic radiation pressure (Krause et al 2011;Plewa et al 2013;Khajenabi 2015). For pressure-confined…”

Section: Introductionmentioning

confidence: 99%

On the orbital motion of cold clouds in broad-line regions

Shadmehri

2015

Mon. Not. R. Astron. Soc.

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“…Recently, Khajenabi (2015) investigated orbital motion of spherical, pressure-confined clouds in the BLR of AGNs, and found that a disk-like configuration is more plausible for the distribution of the BLR clouds. For a pressure-confined cloud, rc(r) ∝ P −1/3 gas , where Pgas is the intercloud gas pressure and Pgas ∝ r −5/2 (Khajenabi 2015). Therefore, the cloud has a radius profile of rc(r) ∝ r 5/6 .…”

Section: Discussionmentioning

confidence: 99%

Revisiting correlations between broad-line and jet emission variations for AGNs: 3C 120 and 3C 273

Liu

Bai

Feng

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We restudy the issue of cross-correlations between broad-line and jet emission variations, and aim to locate the position of radio (and gamma-ray) emitting region in jet of active galactic nuclei (AGNs). Considering the radial profiles of the radius and number density of clouds in a spherical broad-line region (BLR), we derive new formulae connecting jet emitting position R jet to time lag τ ob between broad-line and jet emission variations, and BLR radius. Also, formulae are derived for a disk-like BLR and a spherical shell BLR. The model-independent FR/RSS method is used to estimate τ ob . For 3C 120, positive lags of about 0.3 yr are found between the 15 GHz emission and the Hβ, Hγ and He II λ4686 lines, including broad-line data in a newly published paper, indicating the line variations lead the 15 GHz ones. Each of the broad-line light curves corresponds to a radio outburst. R jet =1.1-1.5 parsec (pc) are obtained for 3C 120. For 3C 273, a common feature of negative time lags is found in the cross-correlation functions between light curves of radio emission and the Balmer lines, and as well Lyα λ1216 and C iv λ1549 lines. R jet = 1.0-2.6 pc are obtained for 3C 273. The estimated R jet are comparable for 3C 120 and 3C 273, and the gamma-ray emitting positions will be within ∼ 1-3 pc from the central engines.Comparisons show that the cloud number density and radius radial distributions and the BLR structures only have negligible effects on R jet .

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“…Radiation forces act on gas motions and make the f S dependent on Eddington ratio [e.g. (Netzer and Marziani, 2010;Khajenabi, 2015)]. The effect can be as large as a factor ≈ 2 and, perhaps more importantly, the efficiency of radiation forces is dependent on the gas column density, leading to the preferential expulsion of gas of lower column density (Netzer and Marziani, 2010).…”

Section: The Virial Factor: Orientation and Radiation Effectsmentioning

confidence: 99%

Past, Present, and Future of the Scaling Relations of Galaxies and Active Galactic Nuclei

D’Onofrio

Marziani

Chiosi

2021

Front. Astron. Space Sci.

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We review the properties of the established Scaling Relations (SRs) of galaxies and active galactic nuclei (AGN), focusing on their origin and expected evolution back in time, providing a short history of the most important progresses obtained up to now and discussing the possible future studies. We also try to connect the observed SRs with the physical mechanisms behind them, examining to what extent current models reproduce the observational data. The emerging picture clarifies the complexity intrinsic to the galaxy formation and evolution process as well as the basic uncertainties still affecting our knowledge of the AGN phenomenon. At the same time, however, it suggests that the detailed analysis of the SRs can profitably contribute to our understanding of galaxies and AGN.

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On the dynamics of clouds in the broad-line region of AGNs with an ADAF atmosphere

Cited by 11 publications

References 27 publications

On the orbital motion of cold clouds in broad-line regions

On the orbital motion of cold clouds in broad-line regions

Revisiting correlations between broad-line and jet emission variations for AGNs: 3C 120 and 3C 273

Past, Present, and Future of the Scaling Relations of Galaxies and Active Galactic Nuclei

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