Fitting AGN/galaxy X-ray-to-radio SEDs with CIGALE and improvement of the code

TL;DR

This paper presents enhancements to the CIGALE code, specifically its X-ray extension X-CIGALE, improving modeling of AGN and galaxy spectral energy distributions across multiple wavelengths, validated on various astronomical samples.

Contribution

The authors identify weaknesses in X-CIGALE and implement improvements related to AGN X-ray anisotropy, X-ray binary emission, and radio emission, enhancing fit quality and physical interpretation.

Findings

AGN X-ray anisotropy is moderate and modeled as $L_X( heta) \\propto 1+\\cos \\theta$

Improvements lead to better fit quality and more accurate physical insights

The updated code is publicly released as CIGALE v2022.0

Abstract

Modern and future surveys effectively provide a panchromatic view for large numbers of extragalactic objects. Consistently modeling these multiwavelength survey data is a critical but challenging task for extragalactic studies. The Code Investigating GALaxy Emission (CIGALE) is an efficient PYTHON code for spectral energy distribution (SED) fitting of galaxies and active galactic nuclei (AGNs). Recently, a major extension of CIGALE (named X-CIGALE) has been developed to account for AGN/galaxy X-ray emission and improve AGN modeling at UV-to-IR wavelengths. Here, we apply X-CIGALE to different samples, including COSMOS spectroscopic type 2 AGNs, CDF-S X-ray detected normal galaxies, SDSS quasars, and COSMOS radio objects. From these tests, we identify several weaknesses of X-CIGALE and improve the code accordingly. These improvements are mainly related to AGN intrinsic X-ray anisotropy, X-ray binary emission, AGN accretion-disk SED shape, and AGN radio emission. These updates improve the fit quality and allow new interpretation of the results, based on which we discuss physical implications. For example, we find that AGN intrinsic X-ray anisotropy is moderate, and can be modeled as $L_X(\theta) \propto 1+\cos \theta$, where $\theta$ is the viewing angle measured from the AGN axis. We merge the new code into the major branch of CIGALE, and publicly release this new version as CIGALE v2022.0 on https://cigale.lam.fr