Structure Growth and the CMB in Modified Gravity (MOG)
  An important piece of evidence for dark matter is the need to explain the
growth of structure from the time of horizon entry and radiation-matter
equality to the formation of stars and galaxies. This cannot be explained by
using general relativity without dark matter. So far, dark matter particles
have not been detected in laboratory measurements or at the LHC. We demonstrate
that enhanced structure growth can happen in a modified gravity theory (MOG).
The vector field and particle introduced in the theory to explain galaxy and
cluster dynamics plays an important role in generating the required structure
growth. The particle called the phion (a light hidden photon) is neutral and is
a dominant, pressureless component in the MOG Friedmann equations, before the
time of decoupling. The dominant energy density of the phion particle in the
early universe, generates an explanation for the growth of density
perturbations. The angular acoustical power spectrum due to baryon-photon
pressure waves is in agreement with the Planck 2013 data. As the universe
expands and large scale structures are formed, the density of baryons dominates
and the rotation curves of galaxies and the dynamics of clusters are explained
in MOG, when the phion particle in the present universe is ultra-light. The
matter power spectrum determined by the theory is in agreement with current
galaxy redshift surveys.
