Suzaku View of the Swift/BAT Active Galactic Nuclei. III. Application of Numerical Torus Models to Two Nearly Compton Thick Active Galactic Nuclei (NGC 612 and NGC 3081)

Abstract

The broadband spectra of two Swift/BAT active galactic nuclei (AGNs) obtained from Suzaku follow-up observations are studied: NGC 612 and NGC 3081. Fitting with standard models, we find that both sources show similar spectra characterized by heavy absorption with N _H ~= 10²⁴ cm^-2, and the fraction of scattered light is f _scat = 0.5%-0.8%, and the solid angle of the reflection component is Ω/2π = 0.4-1.1. To investigate the geometry of the torus, we apply numerical spectral models utilizing Monte Carlo simulations by Ikeda et al. to the Suzaku spectra. We find that our data are well explained by this torus model, which has four geometrical parameters. The fit results suggest that NGC 612 has a torus half-opening angle of sime60°-70° and is observed from a nearly edge-on angle with a small amount of scattering gas, while NGC 3081 has a very small opening angle of sime15° and is observed on a face-on geometry, more like the deeply buried "new type" AGNs found by Ueda et al. We demonstrate the potential power of direct application of such numerical simulations to high-quality broadband spectra to unveil the inner structure of AGNs.