1207.7240 (David F. Mota)

Galaxy Rotation Curves as a probe of Chameleon-Screened Scalar Fields    [PDF]

David F. Mota

I investigate non-minimally coupled scalar field models which present a screening mechanism that allow them to evade local gravity constraints, while at the same time drive the Universe acceleration. I compute both analytically and numerically the scalar field profile and the induced fifth force on the local matter distribution. To obtain the scalar field profiles I use decompositions of galaxy rotation curves into their luminous and their dark matter contributions and solve the scalar field equation of motion for underlying profiles. Taking the galaxy NGC 2841 as an example I derive an upper bound for the scalar field contribution to the rotation curves. Assuming an exponential self-interacting potential, I find the scalar field rotation curve is at least about six orders of magnitude smaller than the dark matter rotation curve. This is true even for coupling strengths several orders of magnitude larger than gravity and the parameters of the exponential self-interacting potential of order one and larger. Considerations on the stability of the chameleon field profile and of the thin-shell effect are also presented and discussed.

View original: http://arxiv.org/abs/1207.7240