Polar dust obscuration in broad-line active galaxies from the XMM-XXL field

Autor: Denis Burgarella, Médéric Boquien, Patrice Theulé, Yannick Roehlly, Laure Ciesla, Marko Stalevski, V. Buat, Guang Yang, G. Mountrichas
Přispěvatelé: Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Laboratory of Image Science and Technology [Nanjing] (LIST), Southeast University [Jiangsu]-School of Computer Science and Engineering, Southeast University [Jiangsu], Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Aix-Marseille Université, Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Ministry of Education, Science and Technological Development (Serbia), Republic of Serbia
Rok vydání: 2021
Předmět:
GALACTIC NUCLEI
Active galactic nucleus
Infrared
Astrophysics::High Energy Astrophysical Phenomena
galaxies: active
Extinction (astronomy)
nuclei [galaxies]
FOS: Physical sciences
Astrophysics::Cosmology and Extragalactic Astrophysics
Astrophysics
01 natural sciences
0103 physical sciences
data analysis [methods]
ABSORPTION
010303 astronomy & astrophysics
TYPE-1
Astrophysics::Galaxy Astrophysics
Line (formation)
High Energy Astrophysical Phenomena (astro-ph.HE)
Physics
HERSCHEL
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
RAY-SELECTED AGN
extinction
010308 nuclear & particles physics
Spectral density
Astronomy and Astrophysics
Astrophysics - Astrophysics of Galaxies
methods: data analysis
Wavelength
SPECTRAL ENERGY-DISTRIBUTION
QUASARS
Physics and Astronomy
[SDU]Sciences of the Universe [physics]
Space and Planetary Science
Astrophysics of Galaxies (astro-ph.GA)
active [galaxies]
X-RAY
Spectral energy distribution
Polar
COVERING FACTOR
Astrophysics::Earth and Planetary Astrophysics
dust
galaxies: nuclei
Astrophysics - High Energy Astrophysical Phenomena
EMISSION
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Zdroj: Astronomy and Astrophysics-A&A
Astronomy and Astrophysics-A&A, EDP Sciences, 2021, 654, pp.A93. ⟨10.1051/0004-6361/202141797⟩
ASTRONOMY & ASTROPHYSICS
Astronomy and Astrophysics-A&A, 2021, 654, pp.A93. ⟨10.1051/0004-6361/202141797⟩
Digital.CSIC. Repositorio Institucional del CSIC
instname
ISSN: 1432-0746
0004-6361
Popis: [Aims]: Dust is observed in the polar regions of nearby active galactic nuclei (AGN) and it is known to contribute substantially to their mid-IR emission and to the obscuration of their UV to optical emission. We aim to carry out a statistical test to check whether this component is a common feature based on an analysis of the integrated spectral energy distributions of these composite sources.
[Methods]: We selected 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 used 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.
[Results]: 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.
The project has received funding from Excellence Initiative of Aix-Marseille University – AMIDEX, a French ‘Investissements d’Avenir’ programme. GM acknowledges support by the Agencia Estatal de Investigacíon, Unidad de Excelencia María de Maeztu, ref. MDM-2017-0765. M.S. acknowledges support by the Ministry of Education, Science and Technological Development of the Republic of Serbia through the contract no. 451-03- 9/2021-14/200002 and by the Science Fund of the Republic of Serbia, PROMIS 6060916, BOWIE.
Databáze: OpenAIRE
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