1999/04/19 by A. Ortiz‐Gil, A. Ortiz-Gil, Kenneth M. Lanzetta +6 · 2 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/307719
16 pages, 3 figures. Accepted for publication in ApJ
arxiv created 1999/04/19 · openalex publication_date 1999/09/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present new Goddard High Resolution Spectrograph observations of Lyα absorption lines associated with a group of galaxies toward the QSO 1545+2101. We have identified eight distinct Lyα absorption features in the spectrum of QSO 1545+2101 at a mean redshift of ⟨ z ⟩ = 0.2648 with a velocity dispersion of 163 km s -1 . A group of galaxies is detected in the vicinity of this QSO at a mean redshift of ⟨ z ⟩ = 0.2645 and velocity dispersion of 239 km s -1 . The identification of discrete absorption systems indicates that they arise in clouds of neutral hydrogen rather than in a diffuse intragroup medium. Our analysis suggests that the Lyα absorption lines are associated with individual galaxies in the group, although a one-to-one relationship between absorbers and galaxies is difficult to establish in such a dense environment.