Extreme quasars as distance indicators in cosmology

Abstract

Quasars accreting matter at very high rates (known as extreme Population A [xA] quasars, possibly associated with super-Eddington accreting massive black holes) may provide a new class of distance indicators covering cosmic epochs from present day up to less than 1 Gyr from the Big Bang. At a more fundamental level, xA quasars are of special interest in studies of the physics of AGNs and host galaxy evolution. However, their observational properties are largely unknown. xA quasars can be identified in relatively large numbers from major optical surveys over a broad range of redshifts, thanks to selection criteria defined from the systematic changes along the quasars main sequence. It has been possible to build a sample of about 250 quasars at low and intermediate redshift, and larger samples can be easily selected from the latest data releases of the Sloan Digital Sky Survey. A large sample can clarify the main properties of xA quasars which are expected - unlike the general population of quasars - to radiate at an extreme, well defined Eddington ratio with small scatter. As a result of the small scatter in Eddington ratio shown by xA quasars, we propose a method to derive the main cosmological parameters based on redshift-independent "virial luminosity" estimates from measurements of emission line widths, roughly equivalent to the luminosity estimates based from line width in early and late type galaxies. A major issue related to the cosmological application of the xA quasar luminosity estimates from line widths is the identification of proper emission lines whose broadening is predominantly virial over a wide range of redshift and luminosity. We report on preliminary developments using the AlIII 1860 intermediate ionization line and the Hydrogen Balmer line H-beta as virial broadening estimators, and we briefly discuss the perspective of the method based on xA quasars.

21 pages, 3 figures

References in corpus (19)

• A Catalog of Quasar Properties from SDSS DR7
• The diversity of quasars unified by accretion and orientation
• CIV 1549 as an Eigenvector 1 Parameter for Active Galactic Nuclei
• Correcting CIV-Based Virial Black Hole Masses
• The Radius-Luminosity Relationship Depends on Optical Spectra in Active Galactic Nuclei
• Supermassive black holes with high accretion rates in active galactic nuclei: II. the most luminous standard candles in the Universe
• Modeling reverberation mapping data I: improved geometric and dynamical models and comparison with cross-correlation results
• Self-shadowing Effects of Slim Accretion Disks in Active Galactic Nuclei: Diverse Appearance of the Broad-line Region
• A spectroscopic analysis of a sample of narrow-line Seyfert 1 galaxies selected from the Sloan Digital Sky Survey
• VLT/ISAAC Spectra of the Hbeta Region in Intermediate-Redshift Quasars III. Hbeta Broad Line Profile Analysis and Inferences about BLR Structure
• New Insights on the QSO Radio-Loud/Radio-Quiet Dichotomy: SDSS Spectra in the Context of the 4D Eigenvector1 Parameter Space
• Highly Accreting Quasars: Sample Definition and Possible Cosmological Implications
• A new cosmological distance measure using AGN X-ray variability
• What does Civλ1549 tell us about the physical driver of the Eigenvector Quasar Sequence?
• Dissecting the quasar main sequence: insight from host galaxy properties
• The phylogeny of quasars and the ontogeny of their central black holes
• Black hole mass estimates in quasars - A comparative analysis of high- and low-ionization lines
• A New Approach to Constrain Black Hole Spins in Active Galaxies Using Optical Reverberation Mapping
• HE0359-3959: an extremely radiating quasar

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