Super-Eddington growth of black holes in the early universe: effects of disc radiation spectra

Takeo, Eishun; Inayoshi, Kohei; Ohsuga, Ken; Takahashi, Hiroyuki R.; Mineshige, Shin

doi:10.1093/mnras/stz1899

Cited by 28 publications

(27 citation statements)

References 120 publications

(156 reference statements)

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“…We also note that the size of an ionized region depends on spectra of radiation. Takeo et al (2019) re-evaluated the transition criteria, taking into account more realistic radiation spectra associated with the properties of nuclear accretion discs that depend on the BH mass and accretion rate. They found that the required density is lowered for less massive BHs because the mean photon energy becomes too high to ionize and heat the ambient gas.…”

Section: Introductionmentioning

confidence: 99%

Hyper-Eddington accretion flows onto black holes accompanied by powerful outflows

Takeo,

Inayoshi,

Mineshige

2020

Preprint

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We perform two-dimensional radiation hydrodynamical simulations of accretion flows onto black holes (BHs) at the nuclei of protogalaxies, and study the impact of mechanical and radiative feedback on rapid growth of BHs. The outflows deposit mass, momentum and energy into the surrounding medium and prevent mass accretion onto the BH, resulting in the reduction of radiative output. We find that when the BH is embedded in a dense gas core, ionizing radiation attenuated by inefficient BH feeding owing to mechanical feedback hardly affects the gas dynamics at the BH gravitational sphere of influence, from which intense inflows of neutral gas occur at rates substantially exceeding the Eddington limit without impeded by photoionization and heating. Since mechanical power of outflows driven by the rapidly accreting BH is sufficiently strong, bipolar outflows completely evacuate the surrounding gas in the polar region but mass inflows through the equatorial region maintain the BH accretion rate as high as ∼ 300 − 10 3 M Edd , which is reduced by one order of magnitude from those with radiative feedback alone. Furthermore, we find that the critical gas density required for rapid accretion is lower by a factor of ∼ 3 nearly independently of BH mass, when mechanical feedback is considered. By studying the dependence on outflow model parameters (e.g., opening angle, mass-loading degree into outflows, velocity), we conclude that contrary to naive expectation, the existence of stronger outflow leads to the transition to rapid accretion phases more efficiently. Rapidly growing BHs inject mechanical power with ∼ 0.1 − 1% of the radiative luminosity into their host galaxy scales, which is used for cosmological simulations.

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Section: Introductionmentioning

confidence: 99%

Hyper-Eddington accretion flows onto black holes accompanied by powerful outflows

Takeo,

Inayoshi,

Mineshige

2020

Preprint

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“…This higher limit is motivated by both observational and theoretical results (see e.g. Takeo et al 2019;Jiang et al 2017). Theoretical models show that such high accretion rates can be indeed frequent, especially at high redshift (see e.g.…”

Section: Accretionmentioning

confidence: 92%

The Rise of Active Galactic Nuclei in the GAlaxy Evolution and Assembly semi-analytic model

Fontanot,

De Lucia,

Hirschmann

et al. 2020

Preprint

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We present a new implementation of the GAlaxy Evolution and Assembly (GAEA) semianalytic model, that features an improved modelling of the process of cold gas accretion onto supermassive black hole (SMBHs), derived from both analytic arguments and high-resolution simulations. We consider different scenarios for the loss of angular momentum required for the available cold gas to be accreted onto the central SMBHs, and we compare different combinations of triggering mechanisms, including galaxy mergers and disk instabilities in star forming discs. We compare our predictions with the luminosity function (LF) observed for Active Galactic Nuclei (AGN) and we confirm that a non-instantaneous accretion timescale (either in the form of a low-angular momentum reservoir or as an assumed light curve evolution) is needed in order to reproduce the measured evolution of the AGN-LF and the so-called AGN-downsizing trend. Moreover, we also study the impact of AGN feedback, in the form of AGN-driven outflows, on the SF properties of model galaxies, using prescriptions derived both from empirical studies or from numerical experiments. We show that AGN-driven outflows are effective in suppressing the residual star formation rate in massive galaxies (> 10 11 M ⊙ ) without changing their overall assembly history. Finally, we study the Eddington ratio distribution as a function of SMBH mass, showing that only objects more massive than 10 8 M ⊙ are already in a self-regulated state as inferred from observations.

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“…As a consequence, photoionisation feedback can not operate efficiently and is unable to halt the inflowing gas, potentially leading to hyper-Eddington accretion (Inayoshi et al 2016). Moreover, the effect of photoionisation feedback may be further reduced for realistic accretion disc spectra, compared to the case of the single power-law spectrum usually assumed in most works (Takeo et al 2019).…”

Section: Physical Implicationsmentioning

confidence: 99%

Supercritical dusty BH growth in the early Universe

Ishibashi

2021

Preprint

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Supermassive black holes (with M BH ∼ 10 9 M ) are observed in the first Gyr of the Universe, and their host galaxies are found to contain unexpectedly large amounts of dust and metals. In light of the two empirical facts, we explore the possibility of supercritical accretion and early black hole growth occurring in dusty environments. We generalise the concept of photon trapping to the case of dusty gas and analyse the physical conditions leading to 'dust photon trapping'. Considering the parameter space dependence, we obtain that the dust photon trapping regime can be more easily realised for larger black hole masses, higher ambient gas densities, and lower gas temperatures. The trapping of photons within the accretion flow implies obscured active galactic nuclei (AGNs), while it may allow a rapid black hole mass build-up at early times. We discuss the potential role of such dust photon trapping in the supercritical growth of massive black holes in the early Universe.

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Super-Eddington growth of black holes in the early universe: effects of disc radiation spectra

Cited by 28 publications

References 120 publications

Hyper-Eddington accretion flows onto black holes accompanied by powerful outflows

Hyper-Eddington accretion flows onto black holes accompanied by powerful outflows

The Rise of Active Galactic Nuclei in the GAlaxy Evolution and Assembly semi-analytic model

Supercritical dusty BH growth in the early Universe

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