MG-II ABSORPTION IN A SAMPLE OF 56 STEEP-SPECTRUM QUASARS

We present an analysis of the statistical properties of Mg II absorber s found in the spectra of 56 intrinsically faint, steep-spectrum radio quasars. We observe for the first time a significant excess of associ ated Mg II absorbers over the number expected from cosmologically dist ributed absorbers. This result is in contrast to previous Mg II survey s in which the QSOs were optically selected. This distinction is simil ar to the result for associated C IV absorbers, in which intrinsically faint, steep-spectrum quasars show excess associated absorption and i ntrinsically bright QSOs (both radio-loud and radio-quiet) do not show an excess. From our spectra a statistically complete list of absorpti on lines is derived, and we find 29 Mg II absorbers, 18 of which have not been previously reported. We also determine several characteristie s of the quasar emission lines in our spectra. The Mg ii absorber dist ribution as a function of redshift and equivalent width is calculated both for our sample alone and from our sample combined with spectra fr om other surveys. For the redshift distribution n(z) = n(1 + z)gamma, we obtain, using the combined sample, the values gamma = 1.11 +/- 0.46 for W(min) = 0.6 angstrom and gamma = 2.47 +/- 0.68 for W(min) = 1.0 angstrom. We find that the distribution of strong absorbers is inconsi stent with no evolution at a confidence level between 2.2 and 2.9 sigm a, depending on the deceleration parameter q0. The deviation from no e volution is similar to what had been previously reported.