2004/03/22 by R. J. Wilman, M. J. Jarvis, H. J. A. Röttgering +2 · 35 citations
Physics and Astronomy · #Absorption (acoustics) #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Intergalactic medium #Intergalactic travel #Intracluster medium #Optics #Physics #Quasar #Radio galaxy #Redshift #Spectral line #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2004.07857.x
published in Monthly Notices of the Royal Astronomical Society 351(3), 1109-1119 (Oxford University Press) · 11 pages, 5 figures; to appear in MNRAS
arxiv created 2004/03/22 · openalex publication_date 2004/06/23 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present VLT-UVES echelle spectra of the Lya emission and absorption in five radio galaxies at redshifts z= 2.55-4.1. Together with data from our pilot study, we have a sample of seven such systems with radio source sizes ∼1-90 kpc with which to address the origin of the absorbing gas. Echelle resolution again reveals that some systems with NH i > 1018 cm-2 in lower-resolution data in fact consist of several weaker absorbers with NH i < 1015 cm-2. We identify two groups of H i absorbers: strong absorbers with NH i 1018-1020 cm-2 and weaker systems with NH i 1013-1015 cm-2. There is none at intermediate NH i. The strong absorbers may be a byproduct of massive galaxy formation or could instead represent material cooling behind the expanding bow shock of the radio jet, as simulated by Krause. New observations are required to discriminate between these possibilities. We argue that the weaker absorbers with NH i 1013-1015 cm-2 are part of the Lya forest, as their rate of incidence is within a factor of 2-4 of that in the intergalactic medium at large. Such column densities are consistent with models of a multiphase proto-intracluster medium at z > 2.