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EW[OIII] as an Orientation Indicator for Quasars: Implications for the Torus

Bisogni, Susanna; Marconi, Alessandro; Risaliti, Guido; Lusso, Elisabeta

EW[OIII] as an Orientation Indicator for Quasars: Implications for the Torus Thumbnail


Authors

Susanna Bisogni

Alessandro Marconi

Guido Risaliti



Abstract

We present an analysis of the average spectral properties of 12,000 SDSS quasars as a function of accretion disc inclination, as measured from the equivalent width of the [OIII] 5007Å line. The use of this indicator on a large sample of quasars from the SDSS DR7 has proven the presence of orientation effects on the features of UV/optical spectra, confirming the presence of outflows in the NLR gas and that the geometry of the BLR is disc-like. Relying on the goodness of this indicator, we are now using it to investigate other bands/components of AGN. Specifically, the study of the UV/optical/IR SED of the same sample provides information on the obscuring “torus.” The SED shows a decrease of the IR fraction moving from face-on to edge-on sources, in agreement with models where the torus is co-axial with the accretion disc. Moreover, the fact we are able to observe the broad emission lines also in sources in an edge-on position, suggests that the torus is rather clumpy than smooth as in the Unified Model. The behavior of the SED as a function of EW[OIII] is in agreement with the predictions of the clumpy torus models as well.

Citation

Bisogni, S., Marconi, A., Risaliti, G., & Lusso, E. (2017). EW[OIII] as an Orientation Indicator for Quasars: Implications for the Torus. Frontiers in Astronomy and Space Sciences, 4, Article 48. https://doi.org/10.3389/fspas.2017.00048

Journal Article Type Article
Acceptance Date Nov 6, 2017
Online Publication Date Nov 21, 2017
Publication Date Nov 21, 2017
Deposit Date Apr 13, 2018
Publicly Available Date Apr 13, 2018
Journal Frontiers in Astronomy and Space Sciences
Electronic ISSN 2296-987X
Publisher Frontiers Media
Peer Reviewed Peer Reviewed
Volume 4
Article Number 48
DOI https://doi.org/10.3389/fspas.2017.00048
Public URL https://durham-repository.worktribe.com/output/1361139

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
© 2017 Bisogni, Marconi, Risaliti and Lusso. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.






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