What Can We Learn about Compton-Thin AGN Tori from Their X-ray Spectra?

have developed a Monte Carlo code for simulation of X-ray spectra of active galactic nuclei (AGN) based on a model of a clumpy obscuring torus. Using this code, we investigate the diagnostic power of X-ray spectroscopy of obscured AGN with respect to the physical properties and orientation of the torus, namely: the average column density, (N-H), the line-of-sight column density, N-H , the abundance of iron, A(Fe) , the clumpiness (i.e., the average number of gas clouds along the line of sight), (N), and the viewing angle, alpha. In this first paper of a series, we consider the Compton-thin case, where both (N-H) and N-H do not exceed 10(24) cm(-2). To enable quantitative comparison of the simulated spectra, we introduce five measurable spectral characteristics: the low-energy hardness ratio (ratio of the continuum fluxes in the 7-11 and 2-7 keV energy bands), the high-energy hardness ratio (ratio of the continuum fluxes in the 10-100 and 2-10 keV energy bands), the depth of the iron K absorption edge, the equivalent width of the Fe K alpha line, and the fraction of the Fe K alpha flux contained in the Compton shoulder. We demonstrate that by means of X-ray spectroscopy it is possible to tightly constrain (N-H), N-H , and A(Fe) in the Compton-thin regime, while there is degeneracy between clumpiness and viewing direction.