Simultaneous effect of Modified Gravity and Primordial Non-Gaussianity
  in Large Scale Structure Observations
  In this work we study the simultaneous effect of primordial non-Gaussianity
and the modification of the gravity in $f(R)$ framework on large scale
structure observations. We show that non-Gaussianity and modified gravity
introduce a scale dependent bias and growth rate functions. The deviation from
$\Lambda$CDM in the case of primordial non-Gaussian models is in large scales,
while the growth rate deviates from $\Lambda$CDM in small scales for modified
gravity theories. We show that the redshift space distortion can be used to
distinguish positive and negative $f_{NL}$ in standard background, while in
$f(R)$ theories they are not easily distinguishable. The galaxy power spectrum
is generally enhanced in presence of non-Gaussianity and modified gravity. We
also obtain the scale dependence of this enhancement. Finally we define galaxy
growth rate and galaxy growth rate bias as new observational parameters to
constrain cosmology.
