Spherical Collapse in Chameleon Models
May, 2010Citations per year
Abstract: (arXiv)
We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In particular, we find that even though the chameleon effects can be potentially large at small scales, for a large enough initial size of the inhomogeneity the collapsing region possesses a thin shell that shields the modification of gravity induced by the chameleon field, recovering the standard gravity results. We analyse the behaviour of a collapsing shell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density for collapse depends on the initial comoving size of the inhomogeneity.Note:
- matches printed version
- chameleon
- field theory: scalar
- gravitation: model
- matter: nonrelativistic
- gravitation: collapse
- geodesic
- density: perturbation
- galaxy: formation
- space-time: Robertson-Walker
- numerical calculations
References(23)
Figures(5)