A Hard Look at Local, Optically Selected, Obscured Seyfert Galaxies

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 > 10²³ cm^-2. We also find a Compton-thick (N_H > 10²⁴ 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. ^* Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 099.A-0403.