Supermassive black hole formation at high redshifts via direct collapse in a cosmological context

Choi, Jun H.; Shlosman, Isaac; Begelman, Mitchell C.

doi:10.1093/mnras/stv694

Cited by 57 publications

(64 citation statements)

References 84 publications

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“…We use fully cosmological initial conditions (ICs) for our models and invoke zoom-in simulations (e.g. Choi et al 2015;Luo et al 2016;Shlosman et al 2016;Luo et al 2018;Ardaneh et al 2018).…”

Section: Initial Conditionsmentioning

confidence: 99%

“…Otherwise, the H 2 cooling can lead to fragmentation and formation of Pop III stars, thus preventing formation of a massive central black hole seed (Haiman et al 2000;Wise & Abel 2008;Begelman & Shlosman 2009;Regan & Haehnelt 2009;Greif et al 2011;Latif et al 2016;Regan & Downes 2018). Numerical simulations of an optically-thin collapse have confirmed that in the absence of a molecular cooling, the gas stays isothermal, at the atomic hydrogen cooling floor (Omukai 2001;Bromm & Loeb 2003;Shang et al 2010;Choi et al 2013Choi et al , 2015Latif et al 2013;Choi et al 2013;Latif et al 2016;Shlosman et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Their existence at high redshifts requires explanation and their evolution is a subject to a fine tuning. The most realistic method to form the SMBH seeds at present remains the direct collapse scenario, which involves the baryonic collapse within dark matter (DM) haloes to form the SMBH seeds of ∼ 10 4 − 10 6 M ⊙ (Rees 1984;Haehnelt & Rees 1993;Loeb & Rasio 1994;Bromm & Loeb 2003;Koushiappas et al 2004;Begelman et al 2006;Begelman et al 2008;Begelman & Shlosman 2009;Begelman 2010;Milosavljević et al 2009;Mayer et al 2010;Johnson et al 2011;Choi et al 2013Choi et al , 2015Latif et al 2013Latif et al , 2014bChon et al 2016;Luo et al 2016Luo et al , 2018Shlosman et al 2016;Ardaneh et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Direct collapse to supermassive black hole seeds: the critical conditions for suppression of H2 cooling

Luo

Shlosman

Nagamine

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Observations of high-redshift quasars imply the presence of supermassive black holes (SMBHs) already at z ∼ 7.5. An appealing and promising pathway to their formation is the direct collapse scenario of a primordial gas in atomic-cooling haloes at z ∼ 10 − 20, when the H 2 formation is inhibited by a strong background radiation field, whose intensity exceeds a critical value, J crit . To estimate J crit , idealized spectra have been assumed, with a fixed ratio of H 2 photo-dissociation rate k H 2 to the H − photodetachment rate k H − . This assumption, however, could be too narrow in scope as the nature of the background radiation field is not known precisely. In this work we show that the critical condition for suppressing the H 2 cooling in the collapsing gas could be described in a more general way by a combination of k H 2 and k H − parameters, without any additional assumptions about the shape of the underlying radiation spectrum. By performing a series of cosmological zoom-in simulations with an encompassing set of k H 2 and k H − , we examine the gas flow by following evolution of basic parameters of the accretion flow. We test under what conditions the gas evolution is dominated by H 2 and/or atomic cooling. We confirm the existence of a critical curve in the k H 2 − k H − plane, and provide an analytical fit to it. This curve depends on the conditions in the direct collapse, and reveals domains where the atomic cooling dominates over the molecular cooling. Furthermore, we have considered the effect of H 2 self-shielding on the critical curve, by adopting three methods for the effective column density approximation in H 2 . We find that the estimate of the characteristic length-scale for shielding can be improved by using λ Jeans25 , which is 0.25 times that of the local Jeans length.

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Section: Initial Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direct collapse to supermassive black hole seeds: the critical conditions for suppression of H2 cooling

Luo

Shlosman

Nagamine

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Runaway collapse of this gas can lead to the formation of a seed BH in the nuclear regions that can retain up to 90% of the Jeans mass (see e.g. Begelman et al 2006;Regan & Haehnelt 2009;Latif et al 2013;Choi et al 2014). Most relevant to the final assembly of DCBHs are then the chemical pathways that involve the formation and destruction of molecular hydrogen in their host haloes.…”

Section: Introductionmentioning

confidence: 99%

New constraints on direct collapse black hole formation in the early Universe

Agarwal

Smith

Glover

et al. 2016

Mon. Not. R. Astron. Soc.

107

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Direct collapse black holes (DCBH) have been proposed as a solution to the challenge of assembling supermassive black holes by z > 6 to explain the bright quasars observed at this epoch. The formation of a DCBH seed with M BH ∼ 10 4−5 M ⊙ requires a pristine atomiccooling halo to be illuminated by an external radiation field that is sufficiently strong to entirely suppress H 2 cooling in the halo. Many previous studies have attempted to constrain the critical specific intensity that is likely required to suppress H 2 cooling, denoted as J crit . However, these studies have typically assumed that the incident external radiation field can be modeled with a black-body spectrum. Under this assumption, it is possible to derive a unique value for J crit that depends only on the temperature of the black-body. In this study we consider a more realistic spectral energy distribution (SED) for the external source of radiation that depends entirely on its star formation history and age. The rate of destruction of the species responsible for suppressing molecular hydrogen cooling depends on the detailed shape of the SED. Therefore the value of J crit is tied to the shape of the incident SED of the neighbouring galaxy. We fit a parametric form to the rates of destruction of H 2 and H − that permit direct collapse. Owing to this, we find that J crit is not a fixed threshold but can lie anywhere in the range J crit ∼ 0.5-10 3 , depending on the details of the source stellar population.

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“…Numerous numerical experiments have been performed to study the direct collapse scenario and show that in the presence of an intense LW flux the formation of molecular hydrogen remains suppressed and the collapse occurs isothermally with T ∼ 8000 K (Bromm & Loeb 2003;Wise et al 2008;Regan & Haehnelt 2009;Latif et al 2013a;Prieto et al 2013;Choi et al 2015;Becerra et al 2015). Moreover, these simulations demonstrate that fragmentation occurs occasionally but large inflow rates of about 0.1−1 M ⊙ /yr are available to grow massive objects in these conditions.…”

Section: Introductionmentioning

confidence: 99%

Witnessing the birth of a supermassive protostar

Latif

Schleicher²,

Hartwig

2016

Mon. Not. R. Astron. Soc.

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The detection of z > 6 quasars reveals the existence of supermassive black holes of a few 10 9 M ⊙ . One of the potential pathways to explain their formation in the infant universe is the so-called direct collapse model which provides massive seeds of 10 5 − 10 6 M ⊙ . An isothermal direct collapse mandates that halos should be of a primordial composition and the formation of molecular hydrogen remains suppressed in the presence of a strong Lyman Werner flux. In this study, we perform high resolution cosmological simulations for two massive primordial halos employing a detailed chemical model which includes H − cooling as well as realistic opacities for both the bound-free H − emission and the Rayleigh scattering of hydrogen atoms. We are able to resolve the collapse up to unprecedentedly high densities of ∼ 10 −3 g/cm 3 and to scales of about 10 −4 AU. Our results show that the gas cools down to ∼ 5000 K in the presence of H − cooling, and induces fragmentation at scales of about 8000 AU in one of the two simulated halos, which may lead to the formation of a binary. In addition, fragmentation also occurs on the AU scale in one of the halos but the clumps are expected to merge on short time scales. Our results confirm that H − cooling does not prevent the formation of a supermassive star and the trapping of cooling radiation stabilises the collapse on small scales.

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Supermassive black hole formation at high redshifts via direct collapse in a cosmological context

Cited by 57 publications

References 84 publications

Direct collapse to supermassive black hole seeds: the critical conditions for suppression of H2 cooling

Direct collapse to supermassive black hole seeds: the critical conditions for suppression of H2 cooling

New constraints on direct collapse black hole formation in the early Universe

Witnessing the birth of a supermassive protostar

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