The bulge-disk decomposition of AGN host galaxies
  We present the results from a study of the morphologies of moderate
luminosity X-ray selected AGN host galaxies in comparison to a carefully
mass-matched control sample at 0.5 < z < 3 in the CANDELS GOODS-S field. We
apply a multi-wavelength morphological decomposition analysis to these two
samples and report on the differences between the morphologies as fitted from
single Sersic and multiple Sersic models, and models which include an
additional nuclear point-source component. Thus, we are able to compare the
widely adopted single Sersic fits from previous studies to the results from a
full morphological decomposition, and address the issue of how biased the
inferred properties of AGN hosts are by a potential nuclear contribution from
the AGN itself. We find that the AGN hosts are mixed systems which have higher
bulge fractions than the control sample in our highest redshift bins at the
>99.7% confidence level, according to all model fits even those which adopt a
point-source component. This serves to alleviate concerns that previous, purely
single Sersic, analyses of AGN hosts could have been spuriously biased towards
higher bulge fractions. This dataset allows us to further probe the physical
nature of these point-source components; we find no strong correlation between
the point-source component and AGN activity, and that these point-source
components are best modelled physically by nuclear starbursts. Our analysis of
the bulge and disk fractions of these AGN hosts in comparison to a mass-matched
control sample reveals a similar morphological evolutionary track for both the
active and non-active populations, providing further evidence in favour of a
model where AGN activity is triggered by secular processes.
