The near-infrared SED of blue quasars: what drives the evolution of the dusty torus?

Abstract

A fundamental ingredient in the unified model of active galactic nuclei (AGN) is the obscuring torus, whose innermost, hottest region dominates the near infrared (NIR) emission. Characterising the change in the torus properties and its interplay with the main AGN emission is key for our understanding of AGN physics, evolution and classification. Its covering factor ($CF$) is largely responsible for the classification of AGN on the basis of the detection of broad emission lines. It is still not clear whether the torus properties evolve over time and how they relate with the accretion parameters of the nucleus. In this work, we aim at investigating the evolution of the NIR properties with the redshift ($z$) and the bolometric luminosity ($L_{\mathrm{bol}}$) of the AGN. To this end, we assembled a large dataset of $\sim$36,000 Type 1 AGN between $0.5<z<2.9$ and $45.0<\log (L_{\mathrm{bol}}/(erg/s))<48.0$ with UV, optical and near-infrared photometry. We produced average spectral energy distributions (SED) in different bins of the $z-L_{\mathrm{bol}}$ parameter space to estimate how the NIR SED evolves according to these parameters. We find that the NIR luminosity decreases for increasing $L_{\mathrm{bol}}$ at any redshift. At the same, time the shape of the NIR SED in our sample is consistent with a non-evolution with $z$. As a consequence, all the explored proxies for the $CF$ exhibit significant anti-correlations with $L_{\mathrm{bol}}$, but not with $z$. Additionally, the $CF$ also shows a shallower anti-correlation with the Eddington ratio (${\lambda }_{\mathrm{Edd}}$), yet current systematic uncertainties, as well as the limited dynamical range, do not allow us to precisely constrain the role of the Eddington ratio. Lastly, we derived the covering factor from the ratio between the NIR and optical luminosity and we employed it to set a lower limit for the X-ray obscuration at different redshifts.

22 pages, 15 figures

References in corpus (56)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• A Catalog of Quasar Properties from SDSS DR7
• A luminous quasar at a redshift of z = 7.085
• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• Initial Performance of the NEOWISE Reactivation Mission
• Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations
• AGN Dusty Tori: I. Handling of Clumpy Media
• BAT AGN Spectroscopic Survey - V. X-ray properties of the Swift/BAT 70-month AGN catalog
• Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy
• Absorption Properties and Evolution of Active Galactic Nuclei
• Universal bolometric corrections for AGN over 7 luminosity decades
• Physical properties of 15 quasars at $z\gtrsim 6.5$
• Obscuration-dependent evolution of Active Galactic Nuclei
• Black hole feedback in the luminous quasar PDS 456
• Dust covering factor, silicate emission and star formation in luminous QSOs
• The first ultraviolet quasar stacked spectrum at z=2.4 from WFC3
• A Catalog of Quasar Properties from Sloan Digital Sky Survey Data Release 16
• Mean Spectral Energy Distributions and Bolometric Corrections for Luminous Quasars
• Quasars as standard candles III. Validation of a new sample for cosmological studies
• The Evolution of Obscuration in AGN
• The effect of radiation pressure on dusty absorbing gas around AGN
• Measuring the Fraction of Obscured Quasars by the Infrared Luminosity of Unobscured Quasars
• HST-COS Observations of AGN. II. Extended Survey of Ultraviolet Composite Spectra from 159 Active Galactic Nuclei
• Dust-free quasars in the early Universe
• Supermassive Black Holes at High Redshift are Expected to be Obscured by their Massive Host Galaxies' Inter Stellar Medium
• On the difference of torus geometry between hidden and non-hidden broad line active galactic nuclei
• Radiation pressure and absorption in AGN: results from a complete unbiased sample from Swift
• Iron K$\alpha$ emission in type-I and type-II Active Galactic Nuclei
• The Size Evolution of Star-forming Galaxies Since z~7 Using ZFOURGE
• Luminosity and Redshift Dependence of the Covering Factor of AGNs viewed with WISE and SDSS
• The quenching of galaxies, bulges, and disks since cosmic noon: A machine learning approach for identifying causality in astronomical data
• Quasars as standard candles II: The non linear relation between UV and X-ray emission at high redshifts
• The most luminous blue quasars at $3.0<z<3.3$. I. A tale of two X-ray populations
• The Intrinsic Far-infrared Continua of Type-1 Quasars
• On the cosmic evolution of AGN obscuration and the X-ray luminosity function: XMM-Newton and Chandra spectral analysis of the 31.3 deg${}^2$ Stripe 82X
• The Galaxy Activity, Torus and Outflow Survey (GATOS): II. Torus and polar dust emission in nearby Seyfert galaxies
• Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies
• Infrared spectra and photometry of complete samples of PG and 2MASS quasars
• How does the Polar Dust affect the Correlation between Dust Covering Factor and Eddington Ratio in Type 1 Quasars Selected from the Sloan Digital Sky Survey Data Release 16?
• Metallicity in Quasar Broad Line Regions at Redshift $\sim$ 6
• BASS XXIX: The near-infrared view of the BLR: the effects of obscuration in BLR characterisation
• Torus and polar dust dependence on AGN properties
• A mid-infrared statistical investigation of clumpy torus model predictions
• The Molecular-Gas Main Sequence and Schmidt-Kennicutt relation are fundamental, the Star-Forming Main Sequence is a (useful) byproduct
• A universal average spectral energy distribution for quasars from optical to extreme ultraviolet
• The WISSH quasars project XI. The mean Spectral Energy Distribution and Bolometric Corrections of the most luminous quasars
• Ray-tracing simulations and spectral models of X-ray radiation in dusty media
• X-ray properties and obscured fraction of AGN in the J1030 Chandra field
• Starbursts and dusty tori in distant 3CR radio galaxies
• An empirical relation to estimate host galaxy stellar light from AGN spectra
• Mg II and Fe II fluxes of luminous quasars at z ~ 2.7 and evaluation of the Baldwin effect in the flux-to-abundance conversion method for quasars
• No redshift evolution in the rest-frame UV emission line properties of quasars from z=1.5 to z=4.0
• Quasars as standard candles VI: spectroscopic validation of the cosmological sample
• Probing the roles of orientation and multi-scale gas distributions in shaping the obscuration of Active Galactic Nuclei through cosmic time
• Quasars as Standard Candles V. Evaluation of a $\le$ 0.06 dex intrinsic dispersion in the LX-LUV relation
• Ensemble Mapping the Inner Structure of Luminous Quasars

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• A big red dot at cosmic noon
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