A New Hope for AGN SED Fitting: X-Ray Spectral Analysis of 12MGS AGN with the C2PO-Torus Model

Carys J. E. Gilbert; Lucia Marchetti; Luigi Barchiesi; Mattia Vaccari; Cristian Vignali; Stefano Marchesi; Francesca Pozzi; Francesco Salvestrini; Anna Feltre; Malebo Moloko; Carlotta Gruppioni

arXiv · 2609.38350

A New Hope for AGN SED Fitting: X-Ray Spectral Analysis of 12MGS AGN with the C2PO-Torus Model

Carys J. E. Gilbert·Lucia Marchetti·Luigi Barchiesi·Mattia Vaccari·Cristian Vignali·Stefano Marchesi·Francesca Pozzi·Francesco Salvestrini·Anna Feltre·Malebo Moloko·Carlotta Gruppioni

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Abstract

In this paper, we present the results of comprehensive, broadband X-ray spectral analysis of a subsample of 43 mid-Infrared (IR) selected star-forming active galactic nuclei (AGN). We analysed archival NuSTAR, Chandra, and XMM-Newton data, and present the first pointed X-ray observation of IRASF03450+0055. We introduce a new physically-based X-ray spectral model, C2PO-Torus, based on a two-phase clumpy torus geometry. It is designed to provide constraints on physical parameters of the torus that can be directly linked to the parameters of the AGN model SKIRTOR. This model will allow us to exploit the synergies between the X-ray and IR regimes, place stronger constraints on the torus properties, and improve spectral energy distribution (SED) fitting by providing priors for the SKIRTOR parameters. We compare the results from the C2PO-Torus fitting to those obtained from traditional models, finding that it is an extremely effective tool for fitting a wide variety of X-ray spectra. We observe that our sample closely follows the established L_[OIII] - L_X AGN relation, while presenting an IR and Radio excess with respect to the L_X - L_12micron and L_X - L_1.4GHz AGN relations at low luminosities. We believe that this excess is due to contamination from star formation related emission. We anticipate that the C2PO-Torus model will aid substantially in completing full-spectrum SED fitting of this sample, allowing us to properly disentangle the different emission components of these objects, which are local analogues of AGN at Cosmic Noon.

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Carys J. E. Gilbert, Lucia Marchetti, Luigi Barchiesi, Mattia Vaccari, Cristian Vignali, Stefano Marchesi, Francesca Pozzi, Francesco Salvestrini, Anna Feltre, Malebo Moloko, Carlotta Gruppioni. 2026-09-29. A New Hope for AGN SED Fitting: X-Ray Spectral Analysis of 12MGS AGN with the C2PO-Torus Model. https://arxiv.org/abs/2609.38350

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