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.