Testing AGN outflow and accretion models with C  iv and He  ii emission line demographics in z ≈ 2 quasars

Matthew J Temple; James H Matthews; Paul C Hewett; Amy L Rankine; Gordon T Richards; Manda Banerji; Gary J Ferland; Christian Knigge; Matthew Stepney

doi:10.1093/mnras/stad1448

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Testing AGN outflow and accretion models with C iv and He ii emission line demographics in z ≈ 2 quasars

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Testing AGN outflow and accretion models with C iv and He ii emission line demographics in z ≈ 2 quasars

Matthew J Temple, James H Matthews, Paul C Hewett, Amy L Rankine, Gordon T Richards, Manda Banerji, Gary J Ferland, Christian Knigge and Matthew Stepney

Monthly notices of the Royal Astronomical Society

15 May 2023

DOI: https://doi.org/10.1093/mnras/stad1448

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Abstract

Abstract Using ≈190,000 spectra from the seventeenth data release of the Sloan Digital Sky Survey, we investigate the ultraviolet emission line properties in z ≈ 2 quasars. Specifically, we quantify how the shape of C iv λ1549 and the equivalent width (EW) of He ii λ1640 depend on the black hole mass and Eddington ratio inferred from Mg ii λ2800. Above L/LEdd ≳ 0.2, there is a strong mass dependence in both C iv blueshift and He ii EW. Large C iv blueshifts are observed only in regions with both high mass and high accretion rate. Including X-ray measurements for a subsample of 5,000 objects, we interpret our observations in the context of AGN accretion and outflow mechanisms. The observed trends in He ii and 2 keV strength are broadly consistent with theoretical qsosed models of AGN spectral energy distributions (SEDs) for low spin black holes, where the ionizing SED depends on the accretion disc temperature and the strength of the soft excess. High spin models are not consistent with observations, suggesting SDSS quasars at z ≈ 2 may in general have low spins. We find a dramatic switch in behaviour at L/LEdd ≲ 0.1: the ultraviolet emission properties show much weaker trends, and no longer agree with qsosed predictions, hinting at changes in the structure of the broad line region. Overall the observed emission line trends are generally consistent with predictions for radiation line driving where quasar outflows are governed by the SED, which itself results from the accretion flow and hence depends on both the SMBH mass and accretion rate.

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Details

Title: Testing AGN outflow and accretion models with C iv and He ii emission line demographics in z ≈ 2 quasars
Creators: Matthew J Temple (Corresponding Author) - Universidad Diego Portales
James H Matthews - University of Oxford
Paul C Hewett - University of Cambridge
Amy L Rankine - Royal Observatory
Gordon T Richards - Drexel University
Manda Banerji - University of Southampton
Gary J Ferland - University of Kentucky
Christian Knigge - University of Southampton
Matthew Stepney - University of Southampton
Publication Details: Monthly notices of the Royal Astronomical Society
Publisher: Oxford University Press
Resource Type: Journal article
Language: English
Academic Unit: Physics
Web of Science ID: WOS:000995754400024
Scopus ID: 2-s2.0-85161627940
Other Identifier: 991020547432504721

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Collaboration types: Domestic collaboration; International collaboration
Web of Science research areas: Astronomy & Astrophysics