Poster Title: A New Approach to Characterizing the SEDs of AGNs from Deep Multi-Wavelength Observations
Abstract: We use data from the CDFN 2 Ms survey and related multi-wavelength observations to investigate the nature of the intrinsic SEDs of AGNs, how they may vary with redshift and luminosity, and how the data may be affected by obscuration and possible contributions from starbursts. Our goal is to find a simple, effective way to use multi-wavelength data to characterize the intrinsic SEDs of AGNs. We believe that shifting the observational data to the emitted frame of the AGN provides a direct way to visualize the effects of obscuration and possible changes in the underlying SED from object to object. This will assist our understanding of the evolution of AGNs and their contribution to the X-ray background. For the 270 point sources in the CDFN catalogue with spectroscopically known redshifts, we transformed the observed flux in each available wavelength band to the emitted flux at the source. In order to characterize the X-ray data we used the published values of gamma_effective. Plots of the SEDs in the emitted frame provide a very useful tool for visualizing effects such as the variation of X-ray slopes and changes in the optical to X-ray flux ratios as a function of redshift and luminosity. For example, we investigate 1) how the Elvis et al. reference SED for low-redshift AGNs compares with the new data, which span a much larger range of redshift and luminosity, 2) how a newly defined alpha_OX based on 2500AA and 8keV fluxes may be a better indicator of the intrinsic properties of AGNs than the traditional one, and 3) what our approach tells us about the nature of low-luminosity AGNs and the contribution of starbursts to the observed multi-wavelength SEDs.
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