---
_id: '17782'
abstract:
- lang: eng
  text: Ultraviolet (UV) radiation from early astrophysical sources could have a large
    impact on subsequent star formation in nearby protogalaxies, and in general on
    the progress of cosmological reionization. Theoretical arguments based on the
    absence of metals in the early Universe suggest that the first stars were likely
    massive, bright, yet short-lived, with lifetimes of a few million years. Here
    we study the radiative feedback arising from such stars using hydrodynamical simulations
    with transient UV backgrounds (UVBs) and persistent Lyman–Werner backgrounds (LWBs)
    of varying intensity. We extend our prior work in Mesinger et al., by studying
    a more typical region whose protogalaxies form at lower redshifts, z∼ 13–20, in
    the epoch likely preceding the bulk of reionization. We confirm our previous results
    that feedback in the relic H ii regions resulting from such transient radiation
    is itself transient. Feedback effects dwindle away after ∼30 per cent of the Hubble
    time, and the same critical specific intensity of JUV∼ 0.1 × 10^−21 erg s^−1 cm^−2
    Hz^−1 sr^−1 separates positive and negative feedback regimes. This suggests that
    overall feedback is fairly insensitive to the large-scale environment, overdensity
    and redshift-dependent halo parameters, and can accurately be modelled in this
    regime with just the intensity of the impinging UVB. Additionally, we discover
    a second episode of eventual positive feedback in haloes which have not yet collapsed
    when their progenitor regions were exposed to the transient UVB. When exposed
    to the transient UVB, this gas suffers relatively little density depletion but
    a significant enhancement of the molecular hydrogen abundance, thus resulting
    in net positive feedback. This eventual positive feedback appears in all runs,
    regardless of the strength of the UVB. However, this feedback regime is very sensitive
    to the presence of Lyman–Werner radiation, and notable effects disappear under
    fairly modest background intensities of JLW≳ 10^−3× 10^−21 erg s^−1 cm^−2 Hz^−1
    sr^−1, assuming the region is optically thin for LW photons. Nevertheless, when
    exposed to the same LWB, haloes inside relic H ii regions always have a higher
    H2 abundance and shorter cooling times than haloes outside relic H ii regions,
    allowing gas to cool faster once it finally begins to collapse on to the halo.
    We conclude that UV radiative feedback in relic H ii regions, although a complicated
    process, seems unlikely to have a major impact on the progress of cosmological
    reionization, provided that present estimates of the lifetime and luminosity of
    a Population III star are accurate. More likely is that the build-up of the LWB
    ultimately governs the feedback strength until a persistent UV background can
    be established.
article_processing_charge: No
article_type: original
author:
- first_name: Andrei
  full_name: Mesinger, Andrei
  last_name: Mesinger
- first_name: Greg L.
  full_name: Bryan, Greg L.
  last_name: Bryan
- first_name: Zoltán
  full_name: Haiman, Zoltán
  id: 7c006e8c-cc0d-11ee-8322-cb904ef76f36
  last_name: Haiman
citation:
  ama: Mesinger A, Bryan GL, Haiman Z. Relic H ii regions and radiative feedback at
    high redshifts. <i>Monthly Notices of the Royal Astronomical Society</i>. 2009;399(3):1650-1662.
    doi:<a href="https://doi.org/10.1111/j.1365-2966.2009.15404.x">10.1111/j.1365-2966.2009.15404.x</a>
  apa: Mesinger, A., Bryan, G. L., &#38; Haiman, Z. (2009). Relic H ii regions and
    radiative feedback at high redshifts. <i>Monthly Notices of the Royal Astronomical
    Society</i>. Oxford University Press. <a href="https://doi.org/10.1111/j.1365-2966.2009.15404.x">https://doi.org/10.1111/j.1365-2966.2009.15404.x</a>
  chicago: Mesinger, Andrei, Greg L. Bryan, and Zoltán Haiman. “Relic H Ii Regions
    and Radiative Feedback at High Redshifts.” <i>Monthly Notices of the Royal Astronomical
    Society</i>. Oxford University Press, 2009. <a href="https://doi.org/10.1111/j.1365-2966.2009.15404.x">https://doi.org/10.1111/j.1365-2966.2009.15404.x</a>.
  ieee: A. Mesinger, G. L. Bryan, and Z. Haiman, “Relic H ii regions and radiative
    feedback at high redshifts,” <i>Monthly Notices of the Royal Astronomical Society</i>,
    vol. 399, no. 3. Oxford University Press, pp. 1650–1662, 2009.
  ista: Mesinger A, Bryan GL, Haiman Z. 2009. Relic H ii regions and radiative feedback
    at high redshifts. Monthly Notices of the Royal Astronomical Society. 399(3),
    1650–1662.
  mla: Mesinger, Andrei, et al. “Relic H Ii Regions and Radiative Feedback at High
    Redshifts.” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 399,
    no. 3, Oxford University Press, 2009, pp. 1650–62, doi:<a href="https://doi.org/10.1111/j.1365-2966.2009.15404.x">10.1111/j.1365-2966.2009.15404.x</a>.
  short: A. Mesinger, G.L. Bryan, Z. Haiman, Monthly Notices of the Royal Astronomical
    Society 399 (2009) 1650–1662.
date_created: 2024-09-06T10:16:16Z
date_published: 2009-10-15T00:00:00Z
date_updated: 2024-09-30T12:42:48Z
day: '15'
doi: 10.1111/j.1365-2966.2009.15404.x
extern: '1'
fulldoi: https://doi.org/10.1111/j.1365-2966.2009.15404.x
intvolume: '       399'
issue: '3'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.1111/j.1365-2966.2009.15404.x
month: '10'
oa: 1
oa_version: Published Version
page: 1650-1662
publication: Monthly Notices of the Royal Astronomical Society
publication_identifier:
  issn:
  - 0035-8711
  - 1365-2966
publication_status: published
publisher: Oxford University Press
quality_controlled: '1'
scopus_import: '1'
status: public
title: Relic H ii regions and radiative feedback at high redshifts
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 399
year: '2009'
...