Galaxy rotation curves in the f(R, T) gravity formalism

Abstract

Astronomical data have shown that the galaxy rotation curves are mostly flat in the far distance of the galactic cores, which could reveal the insufficiency of our knowledge about how gravity works in these regimes. In this paper we introduce a resolution of this issue from the $f(R,T)$ modified gravity formalism perspective. By investigating two classes of models with separable (minimal coupling model) and inseparable (non-minimal coupling model) parts of the Ricci scalar $R$ and trace of the energy-momentum tensor $T$, we find that only in the latter models it is possible to attain flat galaxy rotation curves. Remarkably, those are obtained with no need for dark matter, which can be seen as an $f(R,T)$ gravity advantage, since we still have not probed dark matter particles in laboratory.

Bulk viscous late acceleration under near equilibrium conditions in f(R, T) gravity with mixed dark matter

“…The f(R, T) gravity [48] is one such case, in which one generalizes Einstein's gravity by considering gravitational Lagrangian to be some arbitrary function of the Ricci scalar, R and the trace of the energy momentum tensor of the cosmic component, T. This assumed functional form implies minimal/non-minimal coupling between geometry of the spacetime and matter. Such a coupling between geometry and the trace of energy-momentum tensor can be induced by the imperfect nature of the fluid or through quantum effects and has been extensively investigated in both astrophysical and cosmological contexts [49][50][51][52][53][54]. One after effect of such a minimal/non-minimal coupling, is the appearance of extra terms in the conservation law.…”

Are f(R, Matter) theories really relevant to cosmology?

“…This approach has been used to claim that f (R, Matter) gravity can explain various cosmological and astrophysical observations. In the context of cosmology, those applications range from inflation [14][15][16][17][18][19] to dark matter [20][21][22] and dark energy [23][24][25].…”

Massive scalar field perturbations of black holes immersed in Chaplygin-like dark fluid

“…On the other hand, the large scale structure distributions in the whole Universe and the missing mass in individual galaxies leads to the existence of a new form of matter, termed dark matter (DM), which is assumed to have negligible pressure. The introduction of dark matter may explain the discrepancy between the predicted rotation curves of galaxies when only including luminous matter and the actual (observed) rotation curves which differ significantly [8][9][10]. Besides that, in a effort to explain the dark components of the Universe and to understand and describe the thermal history of the Universe in a unified way novel models that combine dark matter and dark energy were proposed.…”