Enhanced direct collapse due to Lyman <i>α</i> feedback

Johnson, Jarrett L.; Dijkstra, Mark

doi:10.1051/0004-6361/201630010

Cited by 23 publications

(19 citation statements)

References 74 publications

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“…Later Smith et al (2016Smith et al ( , 2017a performed self-consistent MCRT Lyα radiation hydrodynamics (RHD) calculations of galactic winds in the first galaxies, finding that direct collapse black holes (DCBHs), which form in primordial gas, foster an environment that is especially susceptible to Lyα feedback. It has subsequently been found that trapped Lyα cooling radiation potentially affects the initial collapse of these massive black hole seeds through chemical (Johnson & Dijkstra 2017) and thermal (Ge & Wise 2017) feedback. To address the limitations of 1D geometry, Smith et al (2017b) performed a post-processing radiative feedback analysis of a DCBH assembly environment, concluding that fully coupled 3D Lyα RHD will be crucial to consider in future DCBH simulations.…”

Section: Eddington Factormentioning

confidence: 99%

The physics of Lyman α escape from high-redshift galaxies

Smith

Bromm

et al. 2018

Monthly Notices of the Royal Astronomical Society

126

106

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Lyman α (Lyα) photons from ionizing sources and cooling radiation undergo a complex resonant scattering process that generates unique spectral signatures in high-redshift galaxies. We present a detailed Lyα radiative transfer study of a cosmological zoom-in simulation from the Feedback In Realistic Environments (FIRE) project. We focus on the time, spatial, and angular properties of the Lyα emission over a redshift range of z = 5-7, after escaping the galaxy and being transmitted through the intergalactic medium (IGM). Over this epoch, our target galaxy has an average stellar mass of M ≈ 5 × 10 8 M . We find that many of the interesting features of the Lyα line can be understood in terms of the galaxy's star formation history. The time variability, spatial morphology, and anisotropy of Lyα properties are consistent with current observations. For example, the rest frame equivalent width has a EW Lyα,0 > 20Å duty cycle of 62% with a non-negligible number of sightlines with > 100Å, associated with outflowing regions of a starburst with greater coincident UV continuum absorption, as these conditions generate redder, narrower (or single peaked) line profiles. The lowest equivalent widths correspond to cosmological filaments, which have little impact on UV continuum photons but efficiently trap Lyα and produce bluer, broader lines with less transmission through the IGM. We also show that in dense self-shielding, low-metallicity filaments and satellites Lyα radiation pressure can be dynamically important. Finally, despite a significant reduction in surface brightness with increasing redshift, Lyα detections and spectroscopy of high-z galaxies with the upcoming James Webb Space Telescope is feasible.

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Section: Eddington Factormentioning

confidence: 99%

The physics of Lyman α escape from high-redshift galaxies

Smith

Bromm

et al. 2018

Monthly Notices of the Royal Astronomical Society

126

106

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“…However, in realistic situations, the background radiation spectrum is expected to evolve, and hence both k H − and k H 2 will be changing with time. Moreover, trapping of Lyα photons emitted in an optically-thick accretion flow during the direct collapse can affect the gas cooling (e.g., Schleicher et al 2010;Ge & Wise 2017), and even photodetach most of H − (e.g., Johnson & Dijkstra 2017). Under these conditions, the ratio of k H − to k H 2 cannot be calculated simply.…”

Section: Introductionmentioning

confidence: 99%

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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“…They found a dense shell-like outflow structure, formed in response to the central ionizing source, and that Lyα radiation pressure may have a significant dynamical impact on gas surrounding DCBHs. Finally, it has also been suggested that trapped Lyα cooling radiation may enhance the formation of DCBHs by facilitating the photodetachment of H − ions, precursors to H 2 , during collapse (Agarwal & Khochfar 2015;Johnson & Dijkstra 2017). However, all Lyα feedback studies thus far have been limited to 1D geometries.…”

Section: Introductionmentioning

confidence: 99%

Radiative effects during the assembly of direct collapse black holes

Smith

Becerra

Hernquist

2017

Monthly Notices of the Royal Astronomical Society

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We perform a post-processing radiative feedback analysis on a 3D ab initio cosmological simulation of an atomic cooling halo under the direct collapse black hole (DCBH) scenario. We maintain the spatial resolution of the simulation by incorporating native ray-tracing on unstructured mesh data, including Monte Carlo Lyman α (Lyα) radiative transfer. DCBHs are born in gas-rich, metal-poor environments with the possibility of Compton-thick conditions, N H 10 24 cm −2 . Therefore, the surrounding gas is capable of experiencing the full impact of the bottled-up radiation pressure. In particular, we find that multiple scattering of Lyα photons provides an important source of mechanical feedback after the gas in the sub-parsec region becomes partially ionized, avoiding the bottleneck of destruction via the two-photon emission mechanism. We provide detailed discussion of the simulation environment, expansion of the ionization front, emission and escape of Lyα radiation, and Compton scattering. A sink particle prescription allows us to extract approximate limits on the post-formation evolution of the radiative feedback. Fully coupled Lyα radiation hydrodynamics will be crucial to consider in future DCBH simulations.

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Enhanced direct collapse due to Lyman α feedback

Cited by 23 publications

References 74 publications

The physics of Lyman α escape from high-redshift galaxies

The physics of Lyman α escape from high-redshift galaxies

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

Radiative effects during the assembly of direct collapse black holes

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