---
_id: '17690'
abstract:
- lang: eng
  text: The ability of primordial gas to cool in proto-galactic haloes exposed to
    Lyman-Werner (LW) radiation is critically dependent on the self-shielding of H_2.
    We perform radiative transfer calculations of LW line photons, post-processing
    outputs from three-dimensional adaptive mesh refinement (AMR) simulations of haloes
    with T_vir > 10^4 K at redshifts around z=10. We calculate the optically thick
    photodissociation rate numerically, including the effects of density, temperature,
    and velocity gradients in the gas, as well as line overlap and shielding of H_2
    by HI, over a large number of sight-lines. In low-density regions (n<10^4 cm^-3)
    the dissociation rates exceed those obtained using most previous approximations
    by more than an order of magnitude; the correction is smaller at higher densities.
    We trace the origin of the deviations primarily to inaccuracies of (i) the most
    common fitting formula (Draine & Bertoldi 1996) for the suppression of the dissociation
    rate and (ii) estimates for the effective shielding column density from local
    properties of the gas. The combined effects of gas temperature and velocity gradients
    are comparatively less important, typically altering the spherically averaged
    rate only by a factor of less than two. We present a simple modification to the
    DB96 fitting formula for the optically thick rate which improves agreement with
    our numerical results to within approx. 15 per cent, and can be adopted in future
    simulations. We find that estimates for the effective shielding column can be
    improved by using the local Sobolev length. Our correction to the H_2 self-shielding
    reduces the critical LW flux to suppress H_2-cooling in T_vir>10^4 K haloes by
    an order of magnitude; this increases the number of such haloes in which supermassive
    (approx. M=10^5 M_sun) black holes may have formed.
alternative_title:
- H 2 self-shielding in 3D simulations
article_processing_charge: No
article_type: original
author:
- first_name: J.
  full_name: Wolcott-Green, J.
  last_name: Wolcott-Green
- first_name: Zoltán
  full_name: Haiman, Zoltán
  id: 7c006e8c-cc0d-11ee-8322-cb904ef76f36
  last_name: Haiman
- first_name: G. L.
  full_name: Bryan, G. L.
  last_name: Bryan
citation:
  ama: 'Wolcott-Green J, Haiman Z, Bryan GL. Photodissociation of H2 in protogalaxies:
    Modelling self-shielding in three-dimensional simulations. <i>Monthly Notices
    of the Royal Astronomical Society</i>. 2011;418(2):838-852. doi:<a href="https://doi.org/10.1111/j.1365-2966.2011.19538.x">10.1111/j.1365-2966.2011.19538.x</a>'
  apa: 'Wolcott-Green, J., Haiman, Z., &#38; Bryan, G. L. (2011). Photodissociation
    of H2 in protogalaxies: Modelling self-shielding in three-dimensional simulations.
    <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press.
    <a href="https://doi.org/10.1111/j.1365-2966.2011.19538.x">https://doi.org/10.1111/j.1365-2966.2011.19538.x</a>'
  chicago: 'Wolcott-Green, J., Zoltán Haiman, and G. L. Bryan. “Photodissociation
    of H2 in Protogalaxies: Modelling Self-Shielding in Three-Dimensional Simulations.”
    <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press,
    2011. <a href="https://doi.org/10.1111/j.1365-2966.2011.19538.x">https://doi.org/10.1111/j.1365-2966.2011.19538.x</a>.'
  ieee: 'J. Wolcott-Green, Z. Haiman, and G. L. Bryan, “Photodissociation of H2 in
    protogalaxies: Modelling self-shielding in three-dimensional simulations,” <i>Monthly
    Notices of the Royal Astronomical Society</i>, vol. 418, no. 2. Oxford University
    Press, pp. 838–852, 2011.'
  ista: 'Wolcott-Green J, Haiman Z, Bryan GL. 2011. Photodissociation of H2 in protogalaxies:
    Modelling self-shielding in three-dimensional simulations. Monthly Notices of
    the Royal Astronomical Society. 418(2), 838–852.'
  mla: 'Wolcott-Green, J., et al. “Photodissociation of H2 in Protogalaxies: Modelling
    Self-Shielding in Three-Dimensional Simulations.” <i>Monthly Notices of the Royal
    Astronomical Society</i>, vol. 418, no. 2, Oxford University Press, 2011, pp.
    838–52, doi:<a href="https://doi.org/10.1111/j.1365-2966.2011.19538.x">10.1111/j.1365-2966.2011.19538.x</a>.'
  short: J. Wolcott-Green, Z. Haiman, G.L. Bryan, Monthly Notices of the Royal Astronomical
    Society 418 (2011) 838–852.
date_created: 2024-09-06T08:37:08Z
date_published: 2011-11-16T00:00:00Z
date_updated: 2024-09-25T09:53:37Z
day: '16'
doi: 10.1111/j.1365-2966.2011.19538.x
extern: '1'
fulldoi: https://doi.org/10.1111/j.1365-2966.2011.19538.x
intvolume: '       418'
issue: '2'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.1111/j.1365-2966.2011.19538.x
month: '11'
oa: 1
oa_version: Published Version
page: 838-852
publication: Monthly Notices of the Royal Astronomical Society
publication_identifier:
  issn:
  - 0035-8711
publication_status: published
publisher: Oxford University Press
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Photodissociation of H2 in protogalaxies: Modelling self-shielding in three-dimensional
  simulations'
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 418
year: '2011'
...