H I 21 cm observations of the PG 1216+069 sub-damped Lyα absorber field at z = 0.00632

F. H. Briggs, D. G. Barnes

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Abstract

The Westerbork Synthesis Radio Telescope finds a weak 21 cm line emission feature at the coordinates (R.A., decl., velocity) of the sub-damped Lyα (DLA) absorber observed at zabs = 0.00632 in the spectrum of PG 1216+069. The emission feature, WSRT J121921+0639, lies within 30″ of the quasar sight line, is detected at a 99.8% (3 σ) confidence level, has MH I between 5 and 15 × 106 M, and has a velocity spread between 20 and 60 km s-1. Other H I emitters in the field include VCC 297 at a projected distance of 86 h75 -1 kpc and a previously unreported H I cloud, WSRT J121919+0624, at 112 h75 -1 kpc with MH I ∼ 3 × 10 8 M. The optically identified foreground galaxy that is closest to the quasar sight line appears to be VCC 339 (∼L*/25) at 29 h75 -1 kpc with a velocity offset of 292 km s -1. A low surface brightness galaxy with the H I mass of the sub-DLA absorber WSRT J121921+0639 would likely have mB ∼ 17, and its diffuse optical emission would need to compete with the light of both the background QSO and a brighter foreground star ∼10″ from the QSO sight line.

Original languageEnglish
JournalThe Astrophysical Journal
Volume640
Issue number2 II
DOIs
Publication statusPublished - 1 Apr 2006
Externally publishedYes

Keywords

  • Cosmology: observations
  • Galaxies: formation
  • Galaxies: individual (VCC 297, VCC 327, VCC 339)
  • Intergalactic medium
  • Quasars: absorption lines
  • Radio lines: galaxies

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