C iv wind properties of the SDSS-V X-ray selected quasars: strong optical-to-UV emission is key regardless of X-ray strength
Year: 2026
Type: article
Abstract: ABSTRACT We present an investigation of the rest-frame optical/UV and X-ray properties for a sample of 3027 X-ray selected quasars between $1.5 \le z \le 3.5$ detected in the deepest Spectrum Roentgen Gamma/eROSITA data available and observed by the fifth iteration of the Sloan Digital Sky Survey (SDSS-V). We parametrize the C iv $\lambda 1549$ emission line to infer the strength of accretion disc winds and perform X-ray spectral fitting. The X-ray spectral properties – namely, the 2 keV monochromatic luminosity ($L_{2\, \text{keV}}$) and spectral slope – are not strongly correlated with wind strength. Despite this result, the X-ray selected sample is shifted towards lower C iv blueshifts and higher equivalent widths than the optically selected sample observed in previous SDSS surveys, and matching in optical luminosity, redshift, and Eddington ratio does not reduce these differences. We estimate the far-UV luminosity using the He ii $\lambda 1640$ line luminosity and define the slopes between this and the 2500 Å monochromatic luminosity ($L_{2500}$) and $L_{2\, \text{keV}}$ ($\alpha _\text{ouv}$ and $\alpha _\text{uvx}$, respectively) in a similar manner to the familiar $\alpha _\text{ox}$ parameter, which tracks the spectral slope between $L_{2500}$ and $L_{2\, \text{keV}}$. The quantity $\alpha _\text{ouv}$ is more strongly correlated with wind strength in our sample than $\alpha _\text{ox}$. We show that the correlation between $\alpha _\text{ox}$ and wind strength is driven by the relationship between the optical luminosity and wind strength. Our results are consistent with a radiation line-driven wind, whereby the ionizing far-UV photons must not over-ionize the gas. The hard X-ray photons are few enough in number to have a negligible effect on the ionization state of the material.
Authors: Amy L Rankine, David Homan, James Aird, Pranavi Hiremath, Scott F Anderson, Roberto J Assef, Franz E Bauer, W N Brandt, Marcella Brusa, Johannes Buchner, Maria Chira, Yaherlyn Díaz, Patrick B Hall, Anton M Koekemoer, Mirko Krumpe, Georg Lamer, Teng Liu, Sean Morrison, Blessing Musiimenta, C A Negrete, Qingling Ni, Paola Rodríguez Hidalgo, Mara Salvato, Donald P Schneider, Yue Shen, Matthew J Temple, Dusán Tubín-Arenas, Dominika Wylezalek
Institutions: Royal Observatory, University of Edinburgh, University of Cambridge, Leibniz Institute for Astrophysics Potsdam, University of Washington, Universidad Diego Portales, University of Tarapacá, Pennsylvania State University, Astronomical Observatory of Rome, Osservatorio di Astrofisica e Scienza dello Spazio, National Institute for Astrophysics, University of Bologna, Max Planck Institute for Extraterrestrial Physics, National Observatory of Athens, Universidad Técnica Federico Santa María, York University, Space Telescope Science Institute, University of Science and Technology of China, University of Illinois Urbana-Champaign, Universidad Nacional Autónoma de México, University of Washington Bothell, National Center for Supercomputing Applications, Durham University, Heidelberg University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: National Science Foundation, Smithsonian Institution, National Aeronautics and Space Administration, Alfred P. Sloan Foundation, Yale University, Carnegie Institution of Washington, University of Pennsylvania, Ohio State University, California Institute of Technology, Harvard University, University of Utah, Johns Hopkins University, Pennsylvania State University, University of Virginia, New Mexico State University, Space Telescope Science Institute, UK Research and Innovation, Flatiron Health, Leverhulme Trust, École Polytechnique Fédérale de Lausanne, Eberhard Karls Universität Tübingen, University of Toronto, Max-Planck-Gesellschaft, Universität Hamburg, Universidad Nacional Autónoma de México, Yunnan University, Nanjing University, Rheinische Friedrich-Wilhelms-Universität Bonn, China National Textile and Apparel Council, Leibniz-Institut für Astrophysik Potsdam, Hellenic Foundation for Research and Innovation, Agencia Nacional de Investigación y Desarrollo, Max-Planck-Institut für Astronomie, University of Illinois at Urbana-Champaign, University of Colorado Boulder, Smithsonian Astrophysical Observatory, Science and Technology Facilities Council, Leibniz-Gemeinschaft, Russian Academy of Sciences, National Astronomical Observatories, Chinese Academy of Sciences, Fondo Nacional de Desarrollo Científico y Tecnológico
Awards: INSTITUTO MILENIO DE ASTROFISICA, AGNS THROUGH COSMIC TIME HOT DUST OBSCURED GALAXIES AND THE RUBIN LSST, G2428672771, G2598184080, Understanding the Stellar Mass and Environmental Dependences of Cosmic Black-Hole Growth, UNVEILING THE PHYSICAL PROPERTIES OF THE CIRCUMNUCLEAR ENVIRONMENT IN ACTIVE GALACTIC NUCLEI, G2724668986, G342036044, G352144559, G5834573078, G5907811558, EXTREME SPECTRAL VARIABILITY IN ACTIVE GALACTIC NUCLEI - PAVING THE WAY FOR LSST, G7256012066, G73167186, Astronomy at Durham 2023-2026, G7933045695, SPECTRO-TEMPORAL STUDIES OF AGN POPULATIONS, G8728198371, CENTRO DE ASTROFISICA Y TECNOLOGIAS AFINES (CATA)
OpenAlex ID: W7154998143