X‐Ray Emission from Seyfert 2 Galaxies with Optical Polarized Broad Lines

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Abstract
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 1042 to 1043 ergs s-1. The observed X-ray emission is generally only about 1/10 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 percent 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 that Compton scattering dominates the hard X-ray spectrum, as opposed to a purely absorbed nuclear continuum, the efficiency can be less and is similar to that of ordinary Seyfert 2 galaxies. Since the difference between our sample and ordinary Seyfert 2 galaxies can be explained by the difference of viewing angle, the similar scattering efficiency suggests the existence of a scattering region that is larger than the putative dusty torus.
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