A Hard Look at Local, Optically Selected, Obscured Seyfert Galaxies*
Elias Kammoun, J. M. Mïller, Michael Koss, Kyuseok Oh, Abderahmen Zoghbi, R. F. Mushotzky, D. Barret, Ehud Behar, W. N. Brandt, Laura Brenneman, J. S. Kaastra, A. Lohfink, Daniel Proga, Daniel Stern
Abstract
Abstract We study the X-ray spectra of a sample of 19 obscured, optically selected Seyfert galaxies (Sy 1.8, 1.9, and 2) in the local universe ( d ≤ 175 Mpc), drawn from the CfA Seyfert sample. Our analysis is driven by the high sensitivity of NuSTAR in the hard X-rays, coupled with soft X-ray spectra using XMM-Newton, Chandra, Suzaku, and Swift/XRT. We also analyze the optical spectra of these sources in order to obtain accurate mass estimates and Eddington fractions. We employ four different models to analyze the X-ray spectra of these sources, which all provide consistent results. We find that 79%–90% of the sources are heavily obscured with line-of-sight column density N H > 10 23 cm −2 . We also find a Compton-thick ( N H > 10 24 cm −2 ) fraction of 37%–53%. These results are consistent with previous estimates based on multiwavelength analyses. We find that the fraction of reprocessed to intrinsic emission is positively correlated with N H and negatively correlated with the intrinsic, unabsorbed X-ray luminosity (in agreement with the Iwasawa–Taniguchi effect). Our results support the hypothesis that radiation pressure regulates the distribution of the circumnuclear material.