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Highly accreting quasars: The SDSS low-redshift catalog
- Source :
- Digital.CSIC. Repositorio Institucional del CSIC, instname
- Publication Year :
- 2018
- Publisher :
- arXiv, 2018.
-
Abstract
- Context. The most highly accreting quasars are of special interest in studies of the physics of active galactic nuclei (AGNs) and host galaxy evolution. Quasars accreting at high rates (L=LEdd_ 1) hold promise for use as >standard candles>: Distance indicators detectable at very high redshift. However, their observational properties are still largely unknown. Aims. We seek to identify a significant number of extreme accretors. A large sample can clarify the main properties of quasars radiating near L=LEdd_ 1 (in this paper they are designated as extreme Population A quasars or simply as extreme accretors) in the Hβ spectral range for redshift .0:8. Methods. We use selection criteria derived from four-dimensional Eigenvector 1 (4DE1) studies to identify and analyze spectra for a sample of 334 candidate sources identified from the SDSS DR7 database. The source spectra were chosen to show a ratio RFeII between the FeII emission blend at Λ4570 and Hβ, RFeII > 1. Composite spectra were analyzed for systematic trends as a function of Feii strength, line width, and [Oiii] strength. We introduced tighter constraints on the signal-to-noise ratio (S/N) and RFeII values that allowed us to isolate sources most likely to be extreme accretors. Results. We provide a database of detailed measurements. Analysis of the data allows us to confirm that Hβ shows a Lorentzian function with a full width at half maximum (FWHM) of Hβ ≤ 4000 km s. We find no evidence for a discontinuity at 2000 km s in the 4DE1, which could mean that the sources below this FWHM value do not belong to a different AGN class. Systematic [Oiii] blue shifts, as well as a blueshifted component in Hβ are revealed. We interpret the blueshifts as related to the signature of outflowing gas from the quasar central engine. The FWHM of Hβ is still affected by the blueshifted emission; however, the effect is non-negligible if the FWHM Hβ is used as a >virial broadening estimator> (VBE).We emphasize a strong effect of the viewing angle on Hβ broadening, deriving a correction for those sources that shows major disagreement between virial and concordance cosmology luminosity values. Conclusions. The relatively large scatter between concordance cosmology and virial luminosity estimates can be reduced (by an order of magnitude) if a correction for orientation effects is included in the FWHM Hβ value; outflow and sample definition yield relatively minor effects.© ESO 2018.<br />D. Dultzin and A. Negrete acknowledge support form grant IN108716 PAPIIT UNAM and CONACyT project CB-221398. P.M. and M.D.O. acknowledge funding from the INAF PRIN-SKA 2017 program 1.05.01.88.04. M. L. Martínez-Aldama acknowledges a CONACyT postdoctoral fellowship. A. del Olmo, M. L. Martínez-Aldama and J. W. Sulen-tic acknowledge financial support from the Spanish Ministry for Economy and Competitiveness through grants AYA2013-42227-P and AYA2016-76682-C3-1-P. J. This research is part of projects 176003 “Gravitation and the large scale structure of the Universe” and 176001 “Astrophysical spectroscopy of extragalactic objects” supported by the Ministry of Education and Science of the Republic of Serbia.
- Subjects :
- Active galactic nucleus
active [Galaxies]
Astrophysics::High Energy Astrophysical Phenomena
Population
FOS: Physical sciences
Context (language use)
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
01 natural sciences
Luminosity
emission lines [Quasars]
Galaxies: distances and redshifts
0103 physical sciences
distances and redshifts [Galaxies]
Galaxy formation and evolution
010306 general physics
education
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
Galaxies: nuclei
Physics
education.field_of_study
Quasars: emission lines
Cosmic distance ladder
general [Quasars]
Astronomy and Astrophysics
Quasar
Galaxies: active
Catalogues
Astrophysics - Astrophysics of Galaxies
Redshift
Quasars: general
Space and Planetary Science
nuclei [Galaxies]
Astrophysics of Galaxies (astro-ph.GA)
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- Digital.CSIC. Repositorio Institucional del CSIC, instname
- Accession number :
- edsair.doi.dedup.....c8b708e28eb2ff5a6a95b7bcb3fd2a5a
- Full Text :
- https://doi.org/10.48550/arxiv.1809.08310