The Wind Dynamics of Super-Eddington Sources in FRADO

Naddaf, Mohammad-Hassan

doi:10.3390/dynamics2030015

Cited by 3 publications

(2 citation statements)

References 80 publications

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“…We first analyze in detail the model with a black hole mass of 10 8 M ⊙ , solar metallicity, and the flow luminosity corresponding to the Eddington accretion rate. The outflow rate (as in Equation ( 1)) calculated in Naddaf et al [38] for these parameters gives 10 −4 Ṁaccr or 3 × 10 −2 Ṁaccr (where Ṁaccr is the accretion rate of the source) for optically thin or optically thick wind launching, which corresponds to 2 × 10 −4 M ⊙ yr −1 or 6 × 10 −2 M ⊙ yr −1 , respectively. The resolution of the computations gives us directly 866,664 clouds (total mass of 9.7 × 10 −4 M ⊙ for the column density and density of 10 24 cm −2 and 10 12 cm −3 , respectively).…”

Section: Resultsmentioning

confidence: 99%

“…The range of densities is motivated by the most recent observational estimates (e.g., [35]), and by theoretical models of clumpiness based on radiation pressure confinement [36]. The normalization of the total number of clouds is now performed differently, rather following Naddaf and Czerny [37] and Naddaf et al [38], and we concentrate on solutions that show outflowing clouds supplementing the failed part of the wind. The number of clouds at each trajectory in the model itself represents the time spent in completing the path, but the cloud sampling density is arbitrary and each cloud in the computation has the meaning of the effective cloud.…”

Section: Cloud Parameters and The Outflow Net Fluxmentioning

confidence: 99%

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Covering Factor of the Dust-Driven Broad-Line Region Clouds

Naddaf,

Czerny

2024

Universe

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The origin of the broad-line region (BLR) clouds in active galactic nuclei is still under discussion. We develop a scenario in which the clouds in the outer, less ionized part of the BLR are launched by the radiation pressure acting on dust. Most of the outflow forms a failed wind, so we refer to it as failed radiatively accelerated dusty outflow (FRADO), but, for a certain parameter range, actual outflow also takes place. We aim to test the model predictions. In this paper, we present the calculation of the angular distribution of clouds and the net covering factor as this affects the fraction of radiation that can be intercepted and reprocessed in the form of the Hβ or Mg II emission line. The results reveal that the covering factor is intricately linked to the mass, accretion rate, and metallicity of the clouds. Notably, as these parameters increase, so does the covering factor, shedding light on the dynamic interplay between the central engine and the surrounding material in AGNs.

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Section: Resultsmentioning

confidence: 99%

Section: Cloud Parameters and The Outflow Net Fluxmentioning

confidence: 99%

Covering Factor of the Dust-Driven Broad-Line Region Clouds

Naddaf,

Czerny

2024

Universe

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Dust-driven wind as a model of broad absorption line quasars

Naddaf¹,

Martínez-Aldama²,

Marziani³

et al. 2023

A&A

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Context. We test the scenario according to which the broad absorption line (BAL) phenomenon in quasars (QSOs) is not a temporary stage of their life. In this scenario, the BAL effect acts only if the line of sight is within a spatially limited and collimated massive outflow cone covering only a fraction of the sky from the point of view of the nucleus. Aims. The aim is to understand the theoretical mechanism behind the massive outflow in BAL QSOs, which is important for modelling the impact of quasars on the star formation rate in the host galaxy, and, subsequently, on the galaxy evolution. Methods. We applied the specific theoretical model of dust-driven wind that was developed to explain broad emission lines. The model has considerable predictive power. The 2.5D version of the model called failed radiatively accelerated dusty outflow (FRADO) includes the formation of fast funnel-shaped outflow from the disk for a certain range of black hole masses, Eddington ratios, and metallicities. We now interpret BAL QSO as sources that are viewed along the outflowing stream. We calculated the probabilities of seeing the BAL phenomenon as functions of these global parameters, and we compared these probabilities to those seen in the observational data. We included considerations of the presence or absence of obscuring torus. Results. Comparing our theoretical results with observational data for a sample of QSOs consisting of two sub-populations of BAL and non-BAL QSOs, we found that in the model and in the data, the BAL phenomenon mostly occurs for sources with black hole masses higher than 108 M⊙. The effect increases with accretion rate, and high metallicities are also more likely in QSOs showing BAL features if a torus is taken into account. Conclusions. The consistency of the model with the data supports the interpretation of the BAL phenomenon as the result of the orientation of the source. It also supports the underlying theoretical model, although more consistency checks should be made in the future.

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Radio Scrutiny of the X-Ray-weak Tail of Low-mass Active Galactic Nuclei: A Novel Signature of High-Eddington Accretion?

Paul,

Plotkin,

Brandt

et al. 2024

ApJ

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The supermassive black holes (M BH ∼ 106–1010 M ⊙) that power luminous active galactic nuclei (AGNs), i.e., quasars, generally show a correlation between thermal disk emission in the ultraviolet (UV) and coronal emission in hard X-rays. In contrast, some “massive” black holes (mBHs; M BH ∼ 105–106 M ⊙) in low-mass galaxies present curious X-ray properties with coronal radiative output up to 100× weaker than expected. To examine this issue, we present a pilot study incorporating Very Large Array radio observations of a sample of 18 high-accretion-rate (Eddington ratios L bol/L Edd > 0.1), mBH-powered AGNs (M BH ∼ 106 M ⊙) with Chandra X-ray coverage. Empirical correlations previously revealed in samples of radio-quiet, high-Eddington AGNs indicate that the radio–X-ray luminosity ratio, L R/L X, is approximately constant. Through multiwavelength analysis, we instead find that the X-ray-weaker mBHs in our sample tend toward larger values of L R/L X even though they remain radio-quiet per their optical–UV properties. This trend results in a tentative but highly intriguing correlation between L R/L X and X-ray weakness, which we argue is consistent with a scenario in which X-rays may be preferentially obscured from our line of sight by a “slim” accretion disk. We compare this observation to weak emission-line quasars (AGNs with exceptionally weak broad-line emission and a significant X-ray-weak fraction) and conclude by suggesting that our results may offer a new observational signature for finding high-accretion-rate AGNs.

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The Wind Dynamics of Super-Eddington Sources in FRADO

Cited by 3 publications

References 80 publications

Covering Factor of the Dust-Driven Broad-Line Region Clouds

Covering Factor of the Dust-Driven Broad-Line Region Clouds

Dust-driven wind as a model of broad absorption line quasars

Radio Scrutiny of the X-Ray-weak Tail of Low-mass Active Galactic Nuclei: A Novel Signature of High-Eddington Accretion?

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