Volume 646, February 2021
|Number of page(s)||17|
|Published online||02 February 2021|
X-ray flux in SED modelling: An application of X-CIGALE in the XMM-XXL field
Instituto de Fisica de Cantabria (CSIC-Universidad de Cantabria), Avenida de los Castros, 39005 Santander, Spain
2 Aix Marseille Univ., CNRS, CNES, LAM, Marseille, France
3 Institut Universitaire de France (IUF), France
4 Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
5 George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
6 Centro de Astronomía (CITEVA), Universidad de Antofagasta, Avenida Angamos 601, Antofagasta, Chile
Accepted: 18 November 2020
X-CIGALE is built on the spectral energy distribution (SED) code of CIGALE and implements important new features: the code accounts for obscuring material in the poles of AGNs and has the ability to fit X-ray fluxes. In this work, we used ∼2500 spectroscopic X-ray AGNs from the XMM-XXL-north field and examined the improvements the new features bring to the SED modelling analysis. Based on our results, X-CIGALE successfully connects the X-ray with the UV luminosity in the whole range spanned by our sample (log LX(2−10 keV) = (42−46) erg s−1). The addition of the new features generally improves the efficiency of X-CIGALE in the estimation and characterisation of the AGN component. Classification as type 1 or type 2 based on their inclination angle is improved, especially at redshifts lower than 1. The statistical significance of AGN fraction, fracAGN, measurements is increased, in particular for luminous X-ray sources (LX > 1045 erg s−1). These conclusions hold under the condition that (mid-) IR photometry is available in the SED fitting process. The addition of polar dust increases the AGN fraction and the efficiency of the SED decomposition to detect AGNs among X-ray selected sources. X-CIGALE estimates a strong AGN (fracAGN > 0.3) in more than 90% of the IR-selected AGNs and 75% of X-ray-detected AGNs not selected by IR colour criteria. The latter drops to ∼50% when polar dust is not included. The ability of X-CIGALE to include X-ray information in the SED fitting process can be instrumental in the optimal exploitation of the wealth of data that current (eROSITA) and future (ATHENA) missions will provide us.
Key words: galaxies: active / X-rays: galaxies / methods: data analysis / methods: observational / X-rays: general
© ESO 2021
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