Systematic Study of AGN Clumpy Tori with Broadband X-Ray Spectroscopy: Updated Unified Picture of AGN Structure

Abstract

We present the results of a systematic, broadband X-ray spectral analysis of nearby active galactic nuclei (AGNs) with the X-ray clumpy torus model (XCLUMPY). By adding 16 AGNs newly analyzed in this paper, we study a total of 28 AGNs, including unabsorbed and absorbed AGNs taken from Ichikawa et al. and García-Bernete et al. This is the largest sample whose X-ray and infrared spectra are analyzed by the clumpy torus models XCLUMPY and CLUMPY, respectively. The relation between the Eddington ratio and the torus covering factor determined from the X-ray torus parameters of each object follows the trend found by Ricci et al. based on a statistical analysis. We confirm the results by Tanimoto et al. that (1) the torus angular widths determined by the infrared data are larger than those by the X-ray data and (2) the ratios of hydrogen column density to V-band extinction (N_H/A_V) along the line of sight in obscured AGNs are similar to the Galactic value, on average. Unobscured AGNs show apparently smaller line-of-sight N_H/A_V ratios than the Galactic one. Our findings can be well explained by an updated unified picture of AGN structure including a dusty torus, dusty polar outflows, and dust-free gas, where the inclination determines the X-ray and optical classifications and observed torus properties in the X-ray and infrared bands.