Spherical collapse and the halo model in braneworld gravity
Abstract
We present a detailed study of the collapse of a spherical perturbation in DvaliGabadadzePorrati (DGP) braneworld gravity for the purpose of modeling simulation results for the halo mass function, bias, and matter power spectrum. The presence of evolving modifications to the gravitational force in the form of the scalar branebending mode leads to qualitative differences to the collapse in ordinary gravity. In particular, differences in the energetics of the collapse necessitate a new, generalized method for defining the virial radius which does not rely on strict energy conservation. These differences and techniques apply to smooth dark energy models with w≠1 as well. We also discuss the impact of the exterior of the perturbation on collapse quantities due to the lack of a Birkhoff theorem in DGP. The resulting predictions for the mass function, halo bias, and power spectrum are in good overall agreement with DGP Nbody simulations on both the selfaccelerating and normal branch. In particular, the impact of the Vainshtein mechanism as measured in the full simulations is matched well. The model and techniques introduced here can serve as practical tools for placing consistent constraints on braneworld models using observations of largescale structure.
 Publication:

Physical Review D
 Pub Date:
 March 2010
 DOI:
 10.1103/PhysRevD.81.063005
 arXiv:
 arXiv:0911.5178
 Bibcode:
 2010PhRvD..81f3005S
 Keywords:

 95.30.Sf;
 95.36.+x;
 98.80.k;
 98.80.Jk;
 Relativity and gravitation;
 Dark energy;
 Cosmology;
 Mathematical and relativistic aspects of cosmology;
 Astrophysics  Cosmology and Extragalactic Astrophysics
 EPrint:
 20 pages, 16 figures