Spherical collapse in DGP braneworld cosmology
  The DGP (Dvali, Gabadaze and Porrati) braneworld cosmology gives an
alternative to dark energy. In DGP cosmology the alleged cosmic acceleration is
generated by the modification of gravity theory. Nonlinear evolution of matter
density contrast in DGP braneworld cosmology is studied in the present work.
The semi-analytic approach of spherical collapse of matter overdensity is
adopted in the present context to study the nonliner evolution. Further, the
number count of galaxy clusters along the redshift is studied for the DGP
cosmology using Press-Schechter and Sheth-Tormen mass function formalisms. It
is observed that for same values of cosmological parameters, the DGP model
enhances the number of galaxy cluster compared to the standard $\Lambda$CDM
scenario.
