Small scale structure formation in chameleon cosmology

• Published in: Physics letters. B Vol. 633; no. 4-5; pp. 441 - 446
• Main Authors: Brax, Ph, van de Bruck, C., Davis, A.C., Green, A.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 16-02-2006; Elsevier Science
• Subjects: Exact sciences and technology; Nuclear physics; Physics; The physics of elementary particles and fields; Damping; Collapse; Dark matter; Density perturbation; Small scale structure; Cosmology; Models; Scalar fields
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2005.12.055

Chameleon fields are scalar fields whose mass depends on the ambient matter density. We investigate the effects of these fields on the growth of density perturbations on sub-galactic scales and the formation of the first dark matter halos. Density perturbations on comoving scales R<1 pc go non-linear and collapse to form structure much earlier than in standard ΛCDM cosmology. The resulting mini-halos are hence more dense and resilient to disruption. We therefore expect (provided that the density perturbations on these scales have not been erased by damping processes) that the dark matter distribution on small scales would be more clumpy in chameleon cosmology than in the ΛCDM model.