Suzaku Follow-up of Heavily Obscured Active Galactic Nuclei Detected in Swift/BAT Survey: NGC 1106, UGC 03752, and NGC 2788A

TL;DR

This study analyzes the broadband X-ray spectra of three heavily obscured AGNs using Suzaku and Swift/BAT data, applying different torus models to understand their obscuration and geometry.

Contribution

First broadband spectral analysis of these three obscured AGNs with comparison of torus models, highlighting the importance of clumpy torus structures.

Findings

NGC 1106 and NGC 2788A are confirmed as Compton-thick AGNs.

Ikeda torus model provides better spectral fits than MYTorus.

Presence of unabsorbed reflection suggests clumpy torus structures.

Abstract

We present the broadband (0.5-100 keV) spectra of three heavily obscured Active Galactic Nuclei (AGNs), NGC 1106, UGC 03752, and NGC 2788A, observed with Suzaku and Swift/Burst Alert Telescope (BAT). The targets are selected from the Swift/BAT 70-month catalog on the basis of high hardness ratio between above and below 10 keV, and their X-ray spectra are reported here for the first time. We apply three models, a conventional model utilizing an analytic reflection code and two Monte-Carlo based torus models with a doughnut-like geometry (MYTorus) and with a nearly spherical geometry (Ikeda torus). The three models can successfully reproduce the spectra, while the Ikeda torus model gives better description than the MYTorus model in all targets. We identify that NGC 1106 and NGC 2788A as Compton-thick AGNs. We point out that the common presence of unabsorbed reflection components below 7.1 keV in obscured AGNs, as observed from UGC 03752, is evidence for clumpy tori. This implies that detailed studies utilizing clumpy torus models are required to reach correct interpretation of the X-ray spectra of AGNs.