---
res:
  bibo_abstract:
  - High-redshift quasars (z >~ 6) drive ionization fronts into the intergalactic
    medium (IGM). If the thickness of the front can be measured, it can provide a
    novel constraint on the ionizing spectral energy distribution (SED). Here we follow
    the propagation of an I-front into a uniform IGM, and compute its thickness for
    a range of possible quasar spectra and ages. We also explore the effects of uniform
    and non-uniform ionizing backgrounds. We find that even for hard spectra, the
    fronts are initially thin, with a thickness much smaller than the mean free path
    of ionizing photons, but the thickness increases as the front approaches equilibrium
    in 10^8 - 10^9 years, and can eventually significantly exceed simple estimates
    based on the mean free path. With a high intrinsic hydrogen column density obscuring
    the source (log(N_H/cm^-2) >~ 19.2) or a hard power-law spectrum combined with
    some obscuration (e.g. dlog(F_\nu)/dlog(\nu) >~ -1.2 at log(N_H/cm^-2) >~ 18.0),
    the thickness of the front exceeds ~1 physical Mpc and may be measurable from
    the morphology of its redshifted 21cm signal. We find that the highly ionized
    inner part of the front, which may be probed by Lyman line absorption spectra,
    remains sharp for bright quasars unless a large obscuring column (log(N_H/cm^-2)
    >~ 19.2) removes most of their ionizing photons up to ~40 eV. For obscured sources
    with log(N_H/cm^-2) >~ 19.8, embedded in a significantly neutral IGM, the black
    Lyman-alpha trough (where the neutral fraction is ~10^-3) underestimates the size
    of the HII region by a factor of >~4.@eng
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: R. H.
      foaf_name: Kramer, R. H.
      foaf_surname: Kramer
  - foaf_Person:
      foaf_givenName: Zoltán
      foaf_name: Haiman, Zoltán
      foaf_surname: Haiman
      foaf_workInfoHomepage: http://www.librecat.org/personId=7c006e8c-cc0d-11ee-8322-cb904ef76f36
  bibo_doi: 10.1111/j.1365-2966.2008.12945.x
  bibo_issue: '3'
  bibo_volume: 385
  dct_date: 2008^xs_gYear
  dct_isPartOf:
  - http://id.crossref.org/issn/0035-8711
  - http://id.crossref.org/issn/1365-2966
  dct_language: eng
  dct_publisher: Oxford University Press@
  dct_title: The thickness of high-redshift quasar ionization fronts as a constraint
    on the ionizing spectral energy distribution@
...