Evolution in the bias of faint radio sources to z ~ 2.2
  Quantifying how the baryonic matter traces the underlying dark matter
distribution is key to both understanding galaxy formation and our ability to
constrain the cosmological model. Using the cross-correlation function of radio
and near-infrared galaxies, we present a large-scale clustering analysis of
radio galaxies to z ~ 2.2. We measure the angular auto-correlation function of
Ks < 23.5 galaxies in the VIDEO-XMM3 field with photometric redshifts out to z
= 4 using VIDEO and CFHTLS photometry in the near-infrared and optical. We then
use the cross-correlation function of these sources with 766 radio sources at
S_1.4 > 90 {\mu}Jy to infer linear bias of radio galaxies in four redshift
bins. We find that the bias evolves from b = 0.57 +/- 0.06 at z ~ 0.3 to 8.55
+/- 3.11 at z ~ 2.2. Furthermore, we separate the radio sources into subsamples
to determine how the bias is dependent on the radio luminosity, and find a bias
which is significantly higher than predicted by the simulations of Wilman et
al., and consistent with the lower luminosity but more abundant FR-I population
having a similar bias to the highly luminous but rare FR-IIs. Our results are
suggestive of a higher mass, particularly for FR-I sources than assumed in
simulations, especially towards higher redshift.
