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arXiv · 1902.05543

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

Susanna Bisogni·Elisabeta Lusso·Alessandro Marconi·Guido Risaliti
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Abstract

We recently proposed the equivalent width (EW) of the narrow [OIII]5007Å 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 7th Data Release at redshift $z < 0.8$ and with full width at half-maximum values of broad emission lines (H$α$, H$β$, and MgII) larger than $2000$ km/s. 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[OIII]. We find that quasars with low EW[OIII] values (close to face-on position) have flatter near-infrared SEDs with respect to sources with high EW[OIII] values (almost edge-on). Moreover, quasars with high EW[OIII] values show a factor of $\sim 2$ lower emission in the UV to quasars with low EW[OIII] 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.

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Susanna Bisogni, Elisabeta Lusso, Alessandro Marconi, Guido Risaliti. 2019-02-14. Orientation effects on the near-infrared broad band emission of quasars. https://doi.org/10.1093/mnras%2Fstz495

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