A measure of cosmological distance using the Ca ¯ IV Baldwin effect in quasars

Abstract

We use the anticorrelation between the equivalent width (EW) of the Ca ¯IV 1549 emission line and the continuum luminosity in the quasars rest frame (Baldwin effect) to measure their luminosity distance as well as estimate cosmological parameters. We obtain a sample of 471 Type I quasars with the UV-optical spectra and EW (Ca ¯IV) measurements in the redshift range of 2.3'