Journal Article

The host galaxies of strong Ca <span class="smallCaps">ii</span> quasar absorption systems at <i>z</i> < 0.5

Berkeley J. Zych, Michael T. Murphy, Max Pettini, Paul C. Hewett, Emma V. Ryan-Weber and Sara L. Ellison

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 379, issue 4, pages 1409-1422
Published in print August 2007 | ISSN: 0035-8711
Published online July 2007 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1111/j.1365-2966.2007.12015.x
The host galaxies of strong Ca ii quasar absorption systems at z < 0.5

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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 (LL*), 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.

Keywords: galaxies: abundances; galaxies: ISM; quasars: absorption lines

Journal Article.  11275 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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