Relativistic accretion disk reflection in AGN X-ray spectra at z=0.5--4:
  a study of four \textit{Chandra} deep fields
  We confirm that the spectra are best fit by a model containing two Compton
reflection components, one from distant material, and the other displaying
relativistic broadening, most likely from the inner accretion disk. The degree
of relativistic broadening indicates a preference for high black hole spin, but
the reflection is weaker than that expected for a flat disk illuminated by a
point source. We investigate the Compton reflection signatures as a function of
luminosity, redshift and obscuration, confirming an X-ray Baldwin effect for
both the narrow and broad components of the iron line. Anti-correlations are
also seen with redshift and obscuring column density, but are difficult to
disentangle from the Baldwin effect. Our methodology is able to extract
information from multiple spectra with low signal-to-noise ratio, and can be
applied to future data sets such as eROSITA. We show using simulations,
however, that it is necessary to apply an appropriate signal-to-noise ratio cut
to the samples to ensure the spectra add useful information.
