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

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$\alpha$, H$\beta$, 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.

Accepted for publication in MNRAS (8 pages, 4 figures and 2 tables)

References in corpus (10)

• A Catalog of Quasar Properties from SDSS DR7
• AGN Dusty Tori: I. Handling of Clumpy Media
• The diversity of quasars unified by accretion and orientation
• The close environments of accreting massive black holes are shaped by radiative feedback
• Dust covering factor, silicate emission and star formation in luminous QSOs
• Measuring the Fraction of Obscured Quasars by the Infrared Luminosity of Unobscured Quasars
• The WISSH quasars Project: II. Giant star nurseries in hyper-luminous quasars
• Orientation effects on spectral emission features of quasars
• Probing the Active Galactic Nuclei Unified Model Torus Properties in Seyfert Galaxies
• A mid-infrared statistical investigation of clumpy torus model predictions

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• The mid-infrared variability of the SDSS optical quasars
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• Ensemble Mapping the Inner Structure of Luminous Quasars