Lisa M. Winter, Sylvain Veilleux, Barry McKernan, Tim Kallman
We present results from an analysis of the broad-band, 0.3-195 keV, X-ray
spectra of 48 Seyfert 1-1.5 sources detected in the very hard X-rays with the
Swift Burst Alert Telescope (BAT). This sample is selected in an all-sky survey
conducted in the 14-195 keV band. Therefore, our sources are largely unbiased
towards both obscuration and host galaxy properties. Our detailed and uniform
model fits to Suzaku/BAT and XMM-Newton/BAT spectra include the neutral
absorption, direct power-law, reflected emission, soft excess, warm absorption,
and narrow Fe K-alpha emission properties for the entire sample. We
significantly detect O VII and O VIII edges in 52% of our sample. The strength
of these detections are strongly correlated with the neutral column density
measured in the spectrum. Among the strongest detections, X-ray grating and UV
observations, where available, indicate outflowing material. The ionized column
densities of sources with O VII and O VIII detections are clustered in a narrow
range with N$_{\rm warm} \sim 10^{21}$\,cm$^{-2}$, while sources without strong
detections have column densities of ionized gas an order of magnitude lower.
Therefore, we note that sources without strong detections likely have warm
ionized outflows present but at low column densities that are not easily probed
with current X-ray observations. Sources with strong complex absorption have a
strong soft excess, which may or may not be due to difficulties in modeling the
complex spectra of these sources. Still, the detection of a flat Gamma ~ 1 and
a strong soft excess may allow us to infer the presence of strong absorption in
low signal-to-noise AGN spectra. Additionally, we include a useful correction
from the Swift BAT luminosity to bolometric luminosity, based on a comparison
of our spectral fitting results with published spectral energy distribution
fits from 33 of our sources.
View original:
http://arxiv.org/abs/1112.0540
No comments:
Post a Comment