J/A+A/654/A93 Polar dust obscuration in broad-line AGN (Buat+, 2021)
Polar dust obscuration in broad-line active galaxies from the XMM-XXL field.
Buat V., Mountrichas G., Yang G., Boquien M., Roehlly Y., Burgarella D.,
Stalevski M., Ciesla L., Theule P.
<Astron. Astrophys. 654, A93 (2021)>
=2021A&A...654A..93B 2021A&A...654A..93B (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Interstellar medium ; Extinction
Keywords: galaxies: active - galaxies: nuclei - dust, extinction -
methods: data analysis
Abstract:
We study a sample of 1275 broad-line AGN in the XMM-XXL field, with
optical to infrared photometric data. These AGN are seen along their
polar direction and we expect a maximal impact of dust located around
the poles when it is present. We use X-CIGALE, which introduces a dust
component to account for obscuration along the polar directions,
modeled as a foreground screen, and an extinction curve that is chosen
as it steepens significantly at short wavelengths or is much grayer.
By comparing the results of different fits, we are able to define
subsamples of sources with positive statistical evidence in favor of
or against polar obscuration (if present) and described using the gray
or steep extinction curve.
We find a similar fraction of sources with positive evidence for and
against polar dust. Applying statistical corrections, we estimate that
half of our sample could contain polar dust and among them, 60%
exhibit a steep extinction curve and 40% a flat extinction curve;
although these latter percentages are found to depend on the adopted
extinction curves. The obscuration in the V-band is not found to
correlate with the X-ray column density, while AV/NH ratios span a
large range of values and higher dust temperatures are found with the
flat, rather than with the steep extinction curve. Ignoring this polar
dust component in the fit of the spectral energy distribution of these
composite systems leads to an overestimation of the stellar
contribution. A single fit with a polar dust component described with
an SMC extinction curve efficiently overcomes this issue but it fails
at identifying all the AGN with polar dust obscuration.
Description:
Table A.1:
Properties derived for each of the 1212 sources with good XCIGALE
fits. For each source SDSS-ID from SDSS-DR8, spectroscopic redshifts
from Menzel et al. (2016MNRAS.457..110M 2016MNRAS.457..110M, Cat. J/MNRAS/457/110) are
listed. When available, polar dust prescription is summarized: pd
(nopd) for sources for which polar dust (no polar dust) is needed,
when an extinction curve is preferred it is indicated as SMC or G04,
no indication means that nothing is concluded on the presence or not
of polar dust. Polar dust temperature, extinction in the V-band and
their 1 sigma uncertainties are given for sources with polar dust
described by an extinction curve. Secure measurements of star
formation rate and stellar mass, of sources found with or without
polar dust (pd/nopd), are also given with their 1 sigma uncertainties.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 92 1212 Properties derived for each of the 1212 sources
with good XCIGALE fits
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See also:
J/MNRAS/457/110 : Northern XMM-XXL field AGN catalog (Menzel+, 2016)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- objID SDSS objID from SDSS-DR8
21- 28 F8.6 --- z Spectroscopic redshift from Menzel et al.,
2016MNRAS.457..110M 2016MNRAS.457..110M, Cat. J/MNRAS/457/110
30- 33 A4 --- PolDust Polar dust prescription when it is
available (1)
35- 41 F7.2 K Tpd ? Polar dust temperature for sources with
polar dust and a determined extinction
curve
43- 48 F6.2 K e_Tpd ? Polar dust temperature error
50- 53 F4.2 mag AV ? V band attenuation due to polar dust for
sources with polar dust and a determined
extinction curve
55- 58 F4.2 mag e_AV ? V band attenuation error
60- 66 F7.2 Msun/yr SFR ? Star formation rate (2)
68- 74 F7.2 Msun/yr e_SFR ? Star formation rate error
76- 83 E8.3 Msun M* ? Stellar mass (2)
85- 92 E8.3 Msun e_M* ? Stellar mass error
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Note (1): Polar dust prescription from Section 3.3.1 as follows:
pd = is for sources for which polar dust is needed
nopd = is for sources for which no polar dust is needed
SMC = when an extinction curve is preferred, SMC extinction curve
G04 = when an extinction curve is preferred, G04 extinction curve
- = means that nothing is concluded on the presence or not of polar dust
Note (2): for sources found with or without polar dust and with a secure
measurement as defined in Section 3.2, no value is given for the other
sources.
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Acknowledgements:
Veronique Buat, veronique.buat(at)lam.fr
(End) Patricia Vannier [CDS] 11-Aug-2021