Mg II absorbing galaxies

Halos or disks?

Jane Camilla Charlton, Christopher W. Churchill

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

We challenge the conventional view that the majority of Mg II/Lyman limit absorbers are extended halos of galaxies comprised of "clouds" with near-unity covering factor. The gaseous disks of spiral galaxies are known to extend to large radii and likely contribute a significant cross section for absorption. We perform a Monte Carlo survey of QSO fields in which the model galaxies have Mg II absorbing "clouds" in a spherical halo or in a randomly oriented disk. For both geometries, models that recover the observed properties of Mg u absorbers have only a 70%-80% covering factor. Therefore, regardless of absorber geometry, a survey of randomly selected QSO fields should yield a nonnegligible number of nonabsorbing galaxies at small impact parameters. Very few have been observed (Steidel). However, selection effects are important, and once the observational procedures are applied to our model fields, we find that this result is expected. Since both spherical halo and disk models can be made consistent with survey results, we present tests for discerning the geometric distribution of absorbing gas from Hubble Space Telescope images and high-resolution spectra.

Original languageEnglish (US)
Pages (from-to)631-645
Number of pages15
JournalAstrophysical Journal
Volume465
Issue number2 PART I
DOIs
StatePublished - Jan 1 1996

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halos
galaxies
absorbers
quasars
coverings
geometry
image resolution
spiral galaxies
Hubble Space Telescope
unity
cross section
radii
high resolution
cross sections
gases
gas

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Charlton, Jane Camilla ; Churchill, Christopher W. / Mg II absorbing galaxies : Halos or disks?. In: Astrophysical Journal. 1996 ; Vol. 465, No. 2 PART I. pp. 631-645.
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Mg II absorbing galaxies : Halos or disks? / Charlton, Jane Camilla; Churchill, Christopher W.

In: Astrophysical Journal, Vol. 465, No. 2 PART I, 01.01.1996, p. 631-645.

Research output: Contribution to journalArticle

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AU - Churchill, Christopher W.

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