spherical collapse

2008

collapse dynamics, cluster counts, tests of gravity

Spherical collapse of a halo is one of the few instances where the fully nonlinear, relativistic equations of motion can be solved. In particular, our group has worked on collapse in non-standard gravitational models and computed the influence of tidal shear fields, split up into shear and vorticity, on the collapse dynamics. The overdensity needed for spherical collapse allows the prediction of number densities of expected haloes in a cosmic volume, and constraints on cosmological parameters as well as on the gravitational interaction from that quantity.