X-Ray Spectral Properties of Seven Heavily Obscured Seyfert 2 Galaxies

Abstract

We present the combined Chandra and Swift -BAT spectral analysis of seven Seyfert 2 galaxies selected from the Swift -BAT 100 month catalog. We selected nearby ( z  ≤ 0.03) sources lacking a ROSAT counterpart that never previously been observed with Chandra in the 0.3–10 keV energy range, and targeted these objects with 10 ks Chandra ACIS-S observations. The X-ray spectral fitting over the 0.3–150 keV energy range allows us to determine that all the objects are significantly obscured, with N H  ≥ 10 23 cm −2 at a >99% confidence level. Moreover, one to three sources are candidate Compton-thick Active Galactic Nuclei (CT-AGNs; i.e., N H  ≥ 10 24 cm −2 ). We also test the recent spectral curvature method developed by Koss et al. to find candidate CT-AGNs, finding a good agreement between our results and their predictions. Because the selection criteria we adopted were effective in detecting highly obscured AGNs, further observations of these and other Seyfert 2 galaxies selected from the Swift -BAT 100 month catalog will allow us to create a statistically significant sample of highly obscured AGNs, therefore providing a better understanding of the physics of the obscuration processes.