Star formation and accretion in the circumnuclear disks of active galaxies

Wutschik, Stephanie; Schleicher, Dominik R. G.; Palmer, Thomas

doi:10.1051/0004-6361/201321895

Cited by 16 publications

(38 citation statements)

References 86 publications

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“…Star formation in clumpy tori may play a major role in angular momentum transport in tori (e.g., Vollmer & Beckert (2003); Vollmer et al (2008)). Wutschik et al (2013) developed such a model to explain nearby AGNs, obtaining a star formation rate of ∼ 1 M yr −1 in tori. Our measurement implies that the star formation in the torus should not be at an enormous rate, if the star formation governs the gas inflow within the torus.…”

Section: Discussionmentioning

confidence: 99%

Compton Shoulder Diagnostics in Active Galactic Nuclei for Probing the Metallicity of the Obscuring Compton-thick Tori

Hikitani

Ohno

Fukazawa

et al. 2018

ApJ

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We analyzed the spectral shape of the Compton shoulder around the neutral Fe-K α line of the Compton-thick type II Seyfert nucleus of the Circinus galaxy. The characteristics of this Compton shoulder with respect to the reflected continuum and Fe-K α line core intensity are a powerful diagnostics tool for analyzing the structure of the molecular tori, which obscure the central engine. We applied our Monte-Carlo-based X-ray reflection spectral model to the Chandra High Energy Transmission Grating data and successfully constrained the various spectral parameters independently, using only the spectral data only around the Fe-K α emission line. The obtained column density and inclination angle are consistent with the previous observations and the Compton-thick type II Seyfert picture. In addition, we determined the metal abundance of the molecular torus for the case of the smooth and clumpy torus to be 1.75 +0.19 −0.17 and 1.74±0.16 solar abundance, respectively. Such slightly over-solar abundance can be useful information for discussing the star formation rate in the molecular tori of active galactic nuclei.

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Section: Discussionmentioning

confidence: 99%

Compton Shoulder Diagnostics in Active Galactic Nuclei for Probing the Metallicity of the Obscuring Compton-thick Tori

Hikitani

Ohno

Fukazawa

et al. 2018

ApJ

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“…Their formation mechanisms in the juvenile Universe remain unknown. The potential progenitors of SMBHs include the remnants of Pop III stars (Haiman & Loeb 2001;Haiman 2004;Tanaka & Haiman 2009;Whalen & Fryer 2012;Hirano et al 2014;Madau et al 2014), dense stellar cluster (Portegies Zwart et al 2004;Omukai et al 2008;Devecchi & Volonteri 2009) and direct collapse of a protogalactic gas cloud into so-called direct collapse black holes (DCBHs) (Oh & Haiman 2002 Dijkstra et al 2008;Djorgovski et al 2008;Shang et al 2010;Johnson et al 2010;Volonteri 2010;Schleicher et al 2010;Latif et al 2011;Volonteri & Bellovary 2012;Haiman 2012;Prieto et al 2013;Latif et al 2013a,d;Aykutalp et al 2013;Yue et al 2013;Latif et al 2013e;Wutschik et al 2013;Yue et al 2014;Inayoshi et al 2014;Visbal et al 2014).…”

Section: Introductionmentioning

confidence: 99%

A UV flux constraint on the formation of direct collapse black holes

Latif

Bovino

Borm

et al. 2014

Monthly Notices of the Royal Astronomical Society

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The ability of metal free gas to cool by molecular hydrogen in primordial halos is strongly associated with the strength of ultraviolet (UV) flux produced by the stellar populations in the first galaxies. Depending on the stellar spectrum, these UV photons can either dissociate H 2 molecules directly or indirectly by photo-detachment of H − as the latter provides the main pathway for H 2 formation in the early universe. In this study, we aim to determine the critical strength of the UV flux above which the formation of molecular hydrogen remains suppressed for a sample of five distinct halos at z > 10 by employing a higher order chemical solver and a Jeans resolution of 32 cells. We presume that such flux is emitted by PopII stars implying atmospheric temperatures of 10 4 K. We performed three-dimensional cosmological simulations and varied the strength of the UV flux below the Lyman limit in units of J 21 . Our findings show that the value of J crit 21 varies from halo to halo and is sensitive to the local thermal conditions of the gas. For the simulated halos it varies from 400-700 with the exception of one halo where J crit 21 ≥ 1500. This has important implications for the formation of direct collapse black holes and their estimated population at z > 6. It reduces the number density of direct collapse black holes by almost three orders of magnitude compared to the previous estimates.

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“…It is thus certainly viable that fragmentation occurs on some scale, which could potentially contribute to the formation of a starburst ring around the central object (Lodato & Natarajan 2006). In such a case, the further accretion may be regulated by the interplay of gravitational instabilities with stellar feedback (Kawakatu & Wada 2009;Wutschik et al 2013).…”

Section: Summary and Discussionmentioning

confidence: 99%

The chemical evolution of self-gravitating primordial disks

Schleicher

Bovino

Latif

et al. 2015

A&A

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Numerical simulations show the formation of self-gravitating primordial disks during the assembly of the first structures in the Universe, in particular, during the formation of Population III and supermassive stars. Their subsequent evolution is expected to be crucial in determining the mass scale of the first cosmological objects, which depends on the temperature of the gas and dominant cooling mechanism. Here, we derive a one-zone framework to explore the chemical evolution of these disks and show that viscous heating leads to the collisional dissociation of an initially molecular gas. The effect is relevant on scales of 10 AU (1000 AU) for a central mass of 10 M (10 4 M ) at an accretion rate of 10 −1 M yr −1 , and provides a substantial heat input to stabilize the disk. If the gas is initially atomic, it remains atomic during the further evolution and the effect of viscous heating is less significant. The additional thermal support is particularly relevant for the formation of very massive objects, such as the progenitors of the first supermassive black holes. The stabilizing impact of viscous heating thus alleviates the need for strong radiation background as a means of keeping the gas atomic.

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Star formation and accretion in the circumnuclear disks of active galaxies

Cited by 16 publications

References 86 publications

Compton Shoulder Diagnostics in Active Galactic Nuclei for Probing the Metallicity of the Obscuring Compton-thick Tori

Compton Shoulder Diagnostics in Active Galactic Nuclei for Probing the Metallicity of the Obscuring Compton-thick Tori

A UV flux constraint on the formation of direct collapse black holes

The chemical evolution of self-gravitating primordial disks

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