Spectroscopy of PKS 0528-250: New limits on CO absorption and emission

G. E. Jian, Jill Bechtold, Constance Walker, John H. Black

Research output: Contribution to journalArticle

Abstract

We have obtained a moderate-resolution spectrum of the quasar PKS 0528 -250 with the Red Channel Spectrograph on the Multiple Mirror Telescope in order to study a damped Lyα absorption-line system at z = 2.8115. We obtain a new upper limit for the CO column density for the z = 2.8108 velocity component in the z = 2.8115 damped Lyα system. The ionization of different species in this component rules out a quasar spectral energy distribution as the ionization field and implies an ultraviolet radiation field intensity a few times that of the Milky Way value. The estimated total number density is n(H) ∼ 20 cm-3. The physical size for the z = 2.8108 component implied by these models is about 40 pc. The ionization of different species also suggests a structure with a hot intercloud medium associated with a H i cloud in this component, that is, most low ionized ions are from the cold medium where photoionization and photodissociation dominates. The highly ionized species may be from the intercloud medium where collisional ionization dominates. We also present newly identified Ni H absorption lines in the z = 2.1408 and z = 2.8115 damped Lyα systems. The derived depletion of nickel by dust confirms previous results that the dust-to-gas ratio in these two damped Lya systems is about 10% of the Milky Way ratio. Millimeter-wavelength observations obtained at the NRAO 12 m telescope provide new upper limits on CO (3-2) emission in the z = 2.8115 damped Lyα system.

Original languageEnglish (US)
Pages (from-to)727-737
Number of pages11
JournalAstrophysical Journal
Volume486
Issue number2 PART I
DOIs
StatePublished - 1997

Fingerprint

ionization
spectroscopy
quasars
dust
telescopes
ultraviolet radiation
spectral energy distribution
photodissociation
radiation distribution
spectrographs
photoionization
nickel
depletion
mirrors
wavelength
ion
gases
gas
wavelengths
energy

Keywords

  • ISM: abundances
  • ISM: molecules
  • Quasars: absorption lines quasars: individual (PKS 0528-250)

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Spectroscopy of PKS 0528-250 : New limits on CO absorption and emission. / Jian, G. E.; Bechtold, Jill; Walker, Constance; Black, John H.

In: Astrophysical Journal, Vol. 486, No. 2 PART I, 1997, p. 727-737.

Research output: Contribution to journalArticle

Jian, G. E. ; Bechtold, Jill ; Walker, Constance ; Black, John H. / Spectroscopy of PKS 0528-250 : New limits on CO absorption and emission. In: Astrophysical Journal. 1997 ; Vol. 486, No. 2 PART I. pp. 727-737.
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