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Spherical collapse in chameleon models

Spherical collapse in chameleon models We study the gravitational collapse of an overdensity of nonrelativistic matter under theaction of gravity and a chameleon scalar field. We show that the spherical collapse model is modified bythe 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 inhomogeneitythe collapsing region possesses a thin shell that shields the modification of gravity induced by thechameleon field, recovering the standard gravity results. We analysethe behaviour of a collapsingshell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density forcollapse in principle depends on the initial comoving size of the inhomogeneity. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Cosmology and Astroparticle Physics IOP Publishing

Spherical collapse in chameleon models

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References (36)

Copyright
Copyright © IOP Publishing Ltd
eISSN
1475-7516
DOI
10.1088/1475-7516/2010/08/033
Publisher site
See Article on Publisher Site

Abstract

We study the gravitational collapse of an overdensity of nonrelativistic matter under theaction of gravity and a chameleon scalar field. We show that the spherical collapse model is modified bythe 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 inhomogeneitythe collapsing region possesses a thin shell that shields the modification of gravity induced by thechameleon field, recovering the standard gravity results. We analysethe behaviour of a collapsingshell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density forcollapse in principle depends on the initial comoving size of the inhomogeneity.

Journal

Journal of Cosmology and Astroparticle PhysicsIOP Publishing

Published: Aug 1, 2010

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