| Authors : | Dhrubojyoti Sengupta (1,2), Prof. Cristian Viganli (1,2), Dr. Stefano Marchesi (2,3), Prof. Francesca Pozzi (1,2)
(1) Department of Physics and Astronomy (DIFA), University of Bologna, Bologna, Italy
(2) INAF- Observatory of Astrophysics and Space Science (OAS), Bologna, Italy
(3) Department of Physics and Astronomy, Clemson University, Clemson, USA |
| Abstract : | Most of the Cosmic X-ray Background (CXB) radiation from 1 keV to 100 keV is the result of AGN emission. Contribution of unobscured AGN to the CXB is almost completely resolved into point-like sources at E<10 keV, while the detection of obscured AGN, which are responsible for a significant fraction (~40% at the peak) of the CXB emission, is found to be challenging. On the observational side, the obscured Compton-Thick (CT, i.e. those with column density >10^24 cm^-2) AGN fraction ~5-10% in the local universe is much lower than expected from CXB population synthesis models ~20-50%. Therefore, to fill the gap between observations and model predictions, an almost complete census of obscured AGN is needed at different wavelengths. It is commonly accepted that the nuclear obscuration in an AGN-galaxy (at least at low redshift) is caused by the circum-nuclear material of molecular and dusty clouds called ''torus", but its geometrical, physical, and chemical properties are far from being accurately known. On that path, I will present a comprehensive and systematic analysis of few obscured AGN candidates in the local Universe (z < 0.05) through X-ray spectral analysis with Chandra and XMM-Newton at E<10 keV, coupled with NuSTAR data at E>10 keV. The purpose is to examine the properties (i.e., obscuration, covering factor) of the torus from an X-ray point of view over the required broad (~0.5-50 keV) energy range, using physically motivated torus models like- MyTorus, borus02, UxClumpy. Thereafter, I will briefly mention about how we will use multi-component models to analyse the AGN spectral energy distribution (SED) in mid-IR band and finally produce a self-consistent multi-wavelength analysis, i.e. a joint analysis of mid-IR SED-derived view of the obscuring torus with the X-ray perspective. |
