OI and CaII observations in intermediate redshift quasars

Abstract

We present an unprecedented spectroscopic survey of the CaII triplet + OI for a sample of 14 luminous ($-$26 $\gtrsim$ M${}_V$ $\gtrsim$ $-$29), intermediate redshift (0.85 $\lesssim$ $z$ $\lesssim$ 1.65) quasars. The ISAAC spectrometer at ESO VLT allowed us to cover the CaII NIR spectral region redshifted into the H and K windows. We describe in detail our data analysis which enabled us to detect CaII triplet emission in all 14 sources (with the possible exception of HE0048-2804) and to retrieve accurate line widths and fluxes of the triplet and OI $\lambda$8446. The new measurements show trends consistent with previous lower $z$ observations, indicating that CaII and optical FeII emission are probably closely related. The ratio between the CaII triplet and the optical FeII blend at $\lambda$4570 $\mathring{A}$ is apparently systematically larger in our intermediate redshift sample relative to a low-$z$ control sample. Even if this result needs a larger sample for adequate interpretation, higher CaII/optical FeII should be associated with recent episodes of star formation in the intermediate redshift quasars and, at least in part, explain an apparent correlation of CaII triplet equivalent width with $z$ and $L$. The CaII triplet measures yield significant constraints on the emitting region density and ionization parameter, implying CaII triplet emission from log n${}_H$ $\gtrsim$ 11 [cm${}^{-3}$] and ionization parameter log $U$ $\lesssim$ 1.5. Line width and intensity ratios suggest properties consistent with emission from the outer part of a high density broad line region (a line emitting accretion disk?).

66 pages, 15 figures. Accepted for publication in Astrophysical Journal Supplement

References in corpus (12)

• CIV 1549 as an Eigenvector 1 Parameter for Active Galactic Nuclei
• Stellar populations of early-type galaxies in different environments II. Ages and metallicities
• The Near-Infrared Broad Emission Line Region of Active Galactic Nuclei -- I. The Observations
• Stellar populations of early-type galaxies in different environments I. Line-strength indices
• The mass-metallicity gradient relation of early-type galaxies
• VLT/ISAAC Spectra of the Hbeta Region in Intermediate-Redshift Quasars III. Hbeta Broad Line Profile Analysis and Inferences about BLR Structure
• Highly Accreting Quasars: Sample Definition and Possible Cosmological Implications
• Stellar populations of early-type galaxies in different environments III. Line-strength gradients
• VLT/ISAAC Spectra of the H-beta Region in Intermediate-Redshift Quasars II. Black Hole Mass and Eddington Ratio
• Observations of OI and CaII Emission Lines in Quasars: Implications for the Site of FeII Line Emission
• GTC Spectra of z ~ 2.3 Quasars: Comparison with Local Luminosity Analogues
• On the size of the Fe II emitting region in the AGN Akn 120

Cited by in corpus (6)

• A spectroscopic analysis of a sample of narrow-line Seyfert 1 galaxies selected from the Sloan Digital Sky Survey
• What does Civλ1549 tell us about the physical driver of the Eigenvector Quasar Sequence?
• Black hole mass estimates in quasars - A comparative analysis of high- and low-ionization lines
• Panchromatic Properties of the Extreme FeII Emitter PHL 1092
• High Metal Content of Highly Accreting Quasars: Analysis of an Extended Sample
• HE0359-3959: an extremely radiating quasar