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Testing the completeness of the SDSS colour selection for ultramassive, slowly spinning black holes

Bertemes, C.; Trakhtenbrot, B.; Schawinski, K.; Done, C.; Elvis, M.

Testing the completeness of the SDSS colour selection for ultramassive, slowly spinning black holes Thumbnail


Authors

C. Bertemes

B. Trakhtenbrot

K. Schawinski

M. Elvis



Abstract

We investigate the sensitivity of the colour-based quasar selection algorithm of the Sloan Digital Sky Survey (SDSS) to several key physical parameters of supermassive black holes (SMBHs), focusing on BH spin (a*) at the high BH-mass regime (MBH ≥ 109 M⊙). We use a large grid of model spectral energy distribution (SED), assuming geometrically thin, optically thick accretion discs, and spanning a wide range of five physical parameters: BH mass MBH, BH spin a*, Eddington ratio L/LEdd, redshift z, and inclination angle inc. Based on the expected fluxes in the SDSS imaging ugriz bands, we find that ∼99.8 per cent of our models with MBH ≤ 109.5 M⊙ are selected as quasar candidates and thus would have been targeted for spectroscopic follow-up. However, in the extremely high-mass regime, ≥1010 M⊙, we identify a bias against slowly/retrograde spinning SMBHs. The fraction of SEDs that would have been selected as quasar candidates drops below ∼50 per cent for a* < 0 across 0.5 < z < 2. For particularly massive BHs, with MBH ≃ 3 × 1010 M⊙, this rate drops below ∼20 per cent, and can be yet lower for specific redshifts. We further find that the chances of identifying any hypothetical sources with MBH = 1011 M⊙ by colour selection would be extremely low at the level of ∼3 per cent. Our findings, along with several recent theoretical arguments and empirical findings, demonstrate that the current understanding of the SMBH population at the high MBH, and particularly the low- or retrograde-spinning regime, is highly incomplete.

Citation

Bertemes, C., Trakhtenbrot, B., Schawinski, K., Done, C., & Elvis, M. (2016). Testing the completeness of the SDSS colour selection for ultramassive, slowly spinning black holes. Monthly Notices of the Royal Astronomical Society, 463(4), 4041-4051. https://doi.org/10.1093/mnras/stw2207

Journal Article Type Article
Acceptance Date Aug 31, 2016
Online Publication Date Sep 2, 2016
Publication Date Sep 2, 2016
Deposit Date Jul 24, 2017
Publicly Available Date Mar 29, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 463
Issue 4
Pages 4041-4051
DOI https://doi.org/10.1093/mnras/stw2207
Publisher URL https:/doi.org/10.1093/mnras/stw2207

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2016. The Authors.
Published by Oxford University Press on behalf of the Royal Astronomical Society.





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