A polarimetry survey of bright soft X-ray selected ROSAT AGNs

We present the results of a polarimetric survey of 43 bright soft X-ray selected ROSAT AGN. About half the sample were classical Narrow-Line Seyfert 1 galaxies, with FWHM (H beta) < 2,000 km s(-1). We found none of the Narrow-Line Seyfert 1 galaxies to be polarized, supporting the suggestion from rapid X-ray variability and disk-like spectral energy distributions, that we are viewing a bare AGN nucleus. Three sources with FWHM (H beta) > 2,000 km s(-1) show a significant degree of polarization > 1%. For two of the polarized AGN we have measured a wavelength-dependence of the degree of polarization. The soft X-ray emission in these scattered light polarized sources can be explained by 'warm, ionized absorbers', which seem to be linked with outflows in AGN. We compare our results with those Goodrich (1989) found for an optically selected AGN sample.