X-ray emission from Seyfert 2 galaxies with optical polarized broad lines

We analyze the 0.5−10 keV spectra of six Seyfert 2 galaxies observed with the X-ray satellite ASCA: Mrk 3, Mrk 348, Mrk 1210, Mrk 477, NGC 7212, and Was 49b. These galaxies were selected based on their possession of optical polarized broad lines. In the 2−10 keV band, their spectra are heavily absorbed, with 2−10 keV absorption-corrected X-ray luminosities ranging from 10 to 10 ergs s−1. The observed X-ray emission is generally only about one tenth that predicted based on their known infrared and Hβ luminosities. This apparent X-ray weakness can be understood if a considerable fraction of the nuclear activity is completely blocked from view by thick matter along our line of sight to the nucleus. All of these galaxies possess significant soft X-ray emission whose origin appears to be scattered light from their nuclear emission. Based on this hypothesis, we estimate a typical scattering efficiency for X-rays to be about 10%. This efficiency is larger than the few % found for ordinary Seyfert 2 galaxies with no report of optical polarized broad lines. A large scattering efficiency is best explained by an apparent weakness of the hard X-ray luminosity rather than unusually strong scattered light in the soft band. When we estimate the scattering efficiency using the intrinsic luminosity derived assuming 1CREST: Japan Science and Technology Corporation (JST), 4-1-8 Honmachi, Kawaguchi, Saitama 332 2present address: Department of Fundamental Material Science, Faculty of Science, Ehime University, Matsuyama, 790-8577, Japan