J/A+A/697/A223 NIR SED of blue quasars (Trefoloni+, 2025)
The near-infrared spectral energy distribution of blue quasars:
Determining what drives the evolution of the dusty torus.
Trefoloni B., Gilli R., Lusso E., Marconi A., Mazzolari G., Nardini E.,
Risaliti G., Signorini M.
<Astron. Astrophys. 697, A223 (2025)>
=2025A&A...697A.223T 2025A&A...697A.223T (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Energy distributions ; Infrared
Keywords: galaxies: active - galaxies: nuclei - quasars: general -
quasars: supermassive black holes -
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 primary 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
(Lbol) in a sample of AGN. To this end, we assembled a large dataset
of ∼36000 type 1 AGN between 0.5<z<2.9 and
45.0<log(Lbol/(erg/s))<48.0 with UV, optical, and near-infrared
photometry. We produced average spectral energy distributions (SED) in
different bins of the $z-Lbol parameter space to estimate how the
NIR SED evolves according to these parameters. We find that the NIR
luminosity decreases for increasing Lbol 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 Lbol, but not with
z. Additionally, the CF also shows a shallower anti-correlation with
the Eddington ratio (lambdaEdd), yet the 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.
Description:
We gathered a large photometric dataset containing ∼36000 blue quasars
to analyse separately the evolution of the NIR properties of these
type 1 AGN with the redshift and the bolometric luminosity.
All the SEDs are normalised by their integrated luminosity between
1000Å and 1um.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
mast_sed.dat 24 128 Average SED obtained from our sample,
shown in Fig. 9
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Byte-by-byte Description of file: mast_sed.dat
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Bytes Format Units Label Explanations
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1- 5 F5.3 [0.1nm] loglambda log of wavelength
7- 12 F6.3 [10-7W] loglLl Average log of λLλ
14- 18 F5.3 [10-7W] e_loglLl Uncertainty on average log of
λLλ
20- 24 I5 --- Nobj Number of objects contributing to the
spectral channel
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Acknowledgements:
Bartolomeo Trefoloni, bartolomeo.trefoloni(at)unifi.it
(End) Patricia Vannier [CDS] 12-Feb-2025