VLT/ISAAC spectra of the Hβ region in intermediate redshift quasars ^*,**

¹ Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487, USA e-mail: giacomo@merlot.astr.ua.edu
² Osservatorio Astronomico di Bologna, INAF, via Ranzani 1, 40127 Bologna, Italy e-mail: giovanna.stirpe@bo.astro.it
³ Osservatorio Astronomico di Padova, INAF, Vicolo dell' Osservatorio 5, 35122 Padova, Italy e-mail: [marziani; zamanov; calvani]@pd.astro.it
⁴ Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK e-mail: rz@astro.livjm.ac.uk
⁵ Osservatorio Astronomico di Brera, INAF, via Brera 28, 20121 Milano, Italy e-mail: braito@brera.mi.astro.it

Received: 19 December 2003
Accepted: 4 May 2004

Abstract

We present high S/N spectra of the Hβ region in 17 intermediate redshift () quasars. The spectra represent first results of our campaign to test the redshift/luminosity robustness of the so-called Eigenvector 1 (E1) parameter space as developed for low redshift AGN in Sulentic et al. (2000, ApJ, 536, L5). The new quasars span the luminosity range while most of our low redshift sample involve sources in the range . The high redshift sources show E1 parameter values and domain occupation that are similar to our low redshift sample supporting earlier findings that E1 parameters are uncorrelated with source luminosity. Elementary accretion theory can account for a systematic increase of the minimum observed Hβ profile width with source luminosity. Narrow line Seyfert 1 sources with M_B= -28 show FWHM(Hβ) as much as 2000 km s^-1 broader than those with M_B= -22. A possible change in the higher redshift/luminosity sources involves systematically weaker [OIII]4959,5007 narrow line emission.