2007/05/24 by Berkeley J. Zych, M. T. Murphy, Michael T. Murphy +6
Physics and Astronomy · #Absorption (acoustics) #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Emission spectrum #Extinction (optical mineralogy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Optics #Physics #Quasar #Redshift #Sky #Spectral line #Star formation #Velocity dispersion #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2007.12015.x
published as Mon.Not.Roy.Astron.Soc.379:1409-1422,2007 · Accepted for publication in MNRAS, 14 pages, 9 figures. Version with full resolution images available at http://www.ast.cam.ac.uk/~bjz/papers/Zych_etal_2007a.pdf
arxiv created 2007/05/24 · openalex publication_date 2007/07/21 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present new imaging and spectroscopic observations of the fields of five quasars with very strong intervening Ca ii absorption systems at redshifts zabs < 0.5 selected from the Sloan Digital Sky Survey. Recent studies of these very rare absorbers indicate that they may be related to damped Lyman α systems (DLAs). In all five cases, we identify a galaxy at the redshift of the Ca ii system with impact parameters up to ∼24 kpc. In four out of five cases the galaxies are luminous (L≃L*), metal-rich (Z≃ Z⊙), massive (velocity dispersion σ≃ 100 km s−1) spirals. Their star formation rates (SFRs), deduced from Hα emission, are high, in the range SFR = 0.3 –30 M⊙ yr−1. In our analysis, we paid particular attention to correcting the observed emission-line fluxes for stellar absorption and dust extinction. We show that these effects are important for a correct SFR estimate; the difficulties of incorporating such corrections in previous low-z studies of DLA-selected galaxies has probably led to an underestimate of the star formation activity in at least some DLA hosts. We discuss possible links between Ca ii-selected galaxies and DLAs and outline future observations which will help clarify the relationship between these different classes of quasar absorbers.