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Testing AGN outflow and accretion models with CIV and HeII emission line demographics in z=2 quasars

Testing AGN outflow and accretion models with CIV and HeII emission line demographics in z=2 quasars
Testing AGN outflow and accretion models with CIV and HeII emission line demographics in z=2 quasars

Using ≈190 000 spectra from the 17th data release of the Sloan Digital Sky Survey (SDSS), 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/LLEdd ≤ 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 5000 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.

astro-ph.CO, astro-ph.GA, astro-ph.HE, quasars: emission lines
1365-2966
646–666
Temple, Matthew J.
7bbe5840-3c09-445a-81f7-e090d01ff411
Matthews, James H.
8aa37525-32b9-460c-bb83-01c89269ac31
Hewett, Paul C.
a4763f70-9f9a-4a4e-85ed-10694a66e5c9
Rankine, Amy L.
88010438-646c-44d2-95a3-2d9ada0a07eb
Richards, Gordon T.
0192698b-f415-4a89-9ea5-cd5f74a87755
Banerji, Manda
ce0a04bf-70a4-4b64-9027-b1a01def7325
Ferland, Gary J.
56f5a96c-2c17-46d7-b69e-4425427785c5
Knigge, Christian
ac320eec-631a-426e-b2db-717c8bf7857e
Stepney, Matthew
b769a5cf-0fda-4c4c-8e9d-e29c63e4f62a
Temple, Matthew J.
7bbe5840-3c09-445a-81f7-e090d01ff411
Matthews, James H.
8aa37525-32b9-460c-bb83-01c89269ac31
Hewett, Paul C.
a4763f70-9f9a-4a4e-85ed-10694a66e5c9
Rankine, Amy L.
88010438-646c-44d2-95a3-2d9ada0a07eb
Richards, Gordon T.
0192698b-f415-4a89-9ea5-cd5f74a87755
Banerji, Manda
ce0a04bf-70a4-4b64-9027-b1a01def7325
Ferland, Gary J.
56f5a96c-2c17-46d7-b69e-4425427785c5
Knigge, Christian
ac320eec-631a-426e-b2db-717c8bf7857e
Stepney, Matthew
b769a5cf-0fda-4c4c-8e9d-e29c63e4f62a

Temple, Matthew J., Matthews, James H., Hewett, Paul C., Rankine, Amy L., Richards, Gordon T., Banerji, Manda, Ferland, Gary J., Knigge, Christian and Stepney, Matthew (2023) Testing AGN outflow and accretion models with CIV and HeII emission line demographics in z=2 quasars. Monthly Notices of the Royal Astronomical Society, 523 (1), 646–666. (doi:10.1093/mnras/stad1448).

Record type: Article

Abstract

Using ≈190 000 spectra from the 17th data release of the Sloan Digital Sky Survey (SDSS), 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/LLEdd ≤ 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 5000 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.

Text
2301.02675v1 - Accepted Manuscript
Available under License Creative Commons Attribution.
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Accepted/In Press date: 5 May 2023
e-pub ahead of print date: 15 May 2023
Published date: 23 May 2023
Additional Information: Funding Information: Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is www.sdss.org . Funding Information: MJT acknowledges support from a FONDECYT postdoctoral fellowship (3220516). JHM acknowledges funding from the Royal Society. ALR acknowledges support from UKRI (MR/T020989/1). This work made use of astropy (Astropy Collaboration , , ), matplotlib (Hunter ), and numpy (Harris et al. ). Publisher Copyright: © 2023 The Author(s).
Keywords: astro-ph.CO, astro-ph.GA, astro-ph.HE, quasars: emission lines

Identifiers

Local EPrints ID: 474396
URI: http://eprints.soton.ac.uk/id/eprint/474396
ISSN: 1365-2966
PURE UUID: 8de4b0c7-5f1c-4a14-9c34-640142513fe0
ORCID for Manda Banerji: ORCID iD orcid.org/0000-0002-0639-5141

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Date deposited: 21 Feb 2023 17:47
Last modified: 17 Mar 2024 04:01

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Contributors

Author: Matthew J. Temple
Author: James H. Matthews
Author: Paul C. Hewett
Author: Amy L. Rankine
Author: Gordon T. Richards
Author: Manda Banerji ORCID iD
Author: Gary J. Ferland
Author: Matthew Stepney

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