142 research outputs found
A note on viability of nonminimally coupled theory
Consistency conditions for nonminimally coupled theories have been
derived by requiring the absence of tachyons and instabilities in the scalar
fluctuations. This note confirms these results and clarifies a subtlety
regarding different definitions of sound speeds.Comment: 4 pages. -added acknowledgemen
On galaxy rotation curves from a continuum mechanics approach to modified gravity
We consider a modification of General Relativity motivated by the treatment
of anisotropies in Continuum Mechanics. The Newtonian limit of the theory is
formulated and applied to galactic rotation curves. By assuming that the
additional structure of spacetime behaves like a Newtonian gravitational
potential for small deviations from isotropy, we are able to recover the
Navarro-Frenk-White profile of dark matter halos by a suitable identification
of constants. We consider the Burkert profile in the context of our model and
also discuss rotation curves more generally.Comment: 8 pages; v2 11 pages, heavily revised version, new title; v3 13 pages
final versio
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