Orientation effects on the near-infrared broad-band emission of quasars

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

Abstract

We recently proposed the equivalent width (EW) of the narrow [O III]5007 Å emission line as an orientation indicator for active galactic nuclei. We tested this method on about 12 300 optically selected broad-line quasars from the SDSS seventh Data Release at redshift z < 0.8 and with full width at half-maximum values of broad emission lines (H α, H β, and Mg II) larger than 2000 km s−1. We now examine their spectral energy distributions (SEDs) using broad-band photometry from the near-infrared to the ultraviolet to look for variations in the overall shape as a function of the EW[O III]. We find that quasars with low EW[O III] values (close to face-on position) have flatter near-infrared SEDs with respect to sources with high EW[O III] values (almost edge-on). Moreover, quasars with high EW[O III] values show a factor of ∼2 lower emission in the UV to quasars with low EW[O III] values. Our findings indicate that the torus is clumpy and, on average, co-axial with the accretion disc and broad-line region, in agreement with the most recent theoretical models for the obscuring torus.

Citation

Bisogni, S., Lusso, E., Marconi, A., & Risaliti, G. (2019). Orientation effects on the near-infrared broad-band emission of quasars. Monthly Notices of the Royal Astronomical Society, 485(1), 1405-1411. https://doi.org/10.1093/mnras/stz495

• Journal Article Type: Article
• Acceptance Date: Feb 14, 2019
• Online Publication Date: Feb 17, 2019
• Publication Date: May 31, 2019
• Deposit Date: May 29, 2019
• Publicly Available Date: May 29, 2019
• 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: 485
• Issue: 1
• Pages: 1405-1411
• DOI: https://doi.org/10.1093/mnras/stz495
• Public URL: https://durham-repository.worktribe.com/output/1300761