---
_id: '17761'
abstract:
- lang: eng
  text: We explore the possibility of resolving an image of a damped Lyα (DLA) system
    in absorption against an extended, diffuse, background X-ray source. Typical columns
    of neutral hydrogen in DLA systems are high enough to block out up to ~30% of
    the soft X-ray flux at an observed photon energy of 0.5 keV, and we find that
    ~1% of the area of extended X-ray sources at z ≳ 1 have their 0.5 keV flux reduced
    by at least 20% because of intervening DLA systems. We discuss the observability
    of such absorption and find that ≳300 photons per angular resolution element are
    required in the 0.3-8 keV band for its detection and in order to distinguish it
    from intrinsic surface brightness fluctuations. For the surface brightness of
    the currently known high-redshift extended X-ray sources, this requires an integration
    time of a few megaseconds on Chandra, if the maps are smoothed spatially to ≈2''
    resolution. The exact required integration time depends on the DLA system's column
    density, metallicity, and, most strongly, its redshift. Current X-ray telescopes
    are likely to detect DLA systems with N < 10^22 cm^-2 only out to z ≈ 2.3. The
    availability of DLA systems with a suitably high column density for a silhouette
    detection is currently poorly known. We suggest that at low redshifts archival
    data of bright X-ray point sources may be useful in constraining the high-N end
    of the column density distribution. We briefly discuss an alternative strategy
    of searching for extended X-ray sources behind known DLA systems. Although with
    current X-ray telescopes the detections are challenging, they will be within the
    reach of a routine observation with a next generation X-ray telescope, such as
    the X-Ray Evolving Universe Spectrometer (XEUS) or Generation-X, and will deliver
    novel constraints on the nature of protogalaxies.
article_processing_charge: No
article_type: original
author:
- first_name: Mark
  full_name: Dijkstra, Mark
  last_name: Dijkstra
- first_name: Zoltán
  full_name: Haiman, Zoltán
  id: 7c006e8c-cc0d-11ee-8322-cb904ef76f36
  last_name: Haiman
- first_name: Caleb
  full_name: Scharf, Caleb
  last_name: Scharf
citation:
  ama: Dijkstra M, Haiman Z, Scharf C. On detecting the X‐ray silhouette of a damped
    Lyα system. <i>The Astrophysical Journal</i>. 2005;624(1):85-93. doi:<a href="https://doi.org/10.1086/428766">10.1086/428766</a>
  apa: Dijkstra, M., Haiman, Z., &#38; Scharf, C. (2005). On detecting the X‐ray silhouette
    of a damped Lyα system. <i>The Astrophysical Journal</i>. American Astronomical
    Society. <a href="https://doi.org/10.1086/428766">https://doi.org/10.1086/428766</a>
  chicago: Dijkstra, Mark, Zoltán Haiman, and Caleb Scharf. “On Detecting the X‐ray
    Silhouette of a Damped Lyα System.” <i>The Astrophysical Journal</i>. American
    Astronomical Society, 2005. <a href="https://doi.org/10.1086/428766">https://doi.org/10.1086/428766</a>.
  ieee: M. Dijkstra, Z. Haiman, and C. Scharf, “On detecting the X‐ray silhouette
    of a damped Lyα system,” <i>The Astrophysical Journal</i>, vol. 624, no. 1. American
    Astronomical Society, pp. 85–93, 2005.
  ista: Dijkstra M, Haiman Z, Scharf C. 2005. On detecting the X‐ray silhouette of
    a damped Lyα system. The Astrophysical Journal. 624(1), 85–93.
  mla: Dijkstra, Mark, et al. “On Detecting the X‐ray Silhouette of a Damped Lyα System.”
    <i>The Astrophysical Journal</i>, vol. 624, no. 1, American Astronomical Society,
    2005, pp. 85–93, doi:<a href="https://doi.org/10.1086/428766">10.1086/428766</a>.
  short: M. Dijkstra, Z. Haiman, C. Scharf, The Astrophysical Journal 624 (2005) 85–93.
date_created: 2024-09-06T09:48:59Z
date_published: 2005-05-01T00:00:00Z
date_updated: 2024-09-30T08:55:54Z
day: '01'
doi: 10.1086/428766
extern: '1'
intvolume: '       624'
issue: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.1086/428766
month: '05'
oa: 1
oa_version: Published Version
page: 85-93
publication: The Astrophysical Journal
publication_identifier:
  issn:
  - 0004-637X
  - 1538-4357
publication_status: published
publisher: American Astronomical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: On detecting the X‐ray silhouette of a damped Lyα system
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 624
year: '2005'
...