Galactic rotation curves of spiral galaxies and dark matter in $f(\mathcal{R},T)$ gravity theory

Abstract

Galactic rotation curve is a powerful indicator of the state of the gravitational field within a galaxy. Flatness of these curves implies the linear increase of mass to have constant velocity with the radial distance. In this paper, we focus on the possibility of explaining the flatness of observed rotation curves of spiral galaxies without postulating the existence of dark matter in the framework of f (R, T ) gravity where the gravitational Lagrangian is written by an arbitrary function of R, the Ricci scalar and of T , the trace of stress-energy tensor Tµν . We derive the gravitational field equations in this gravity theory for the static spherically symmetric spacetime and solve the equations for metric coefficients using a specific model that has minimal coupling between matter and geometry. The orbital motion of a massive test particle moving in a stable circular orbit is considered and the behaviour of tangential velocity in the halo region with the help of the considered model is studied. The linear variation with distance of the interaction mass generated due to matter-geometry coupling successfully explains the galactic dynamics without the existence of dark matter at large distances from the galactic core.

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

“…Here, we will check if f (R, T) gravity is able to fit the observations in the galactic regime with no need to impose the existence of a dark matter halo. It is worthy of mentioning that, recently, in [49] the problem of rotation curves has been discussed in f (R, T) gravity. 4 Finally, one finds some recent attempts in favor of the modified gravity explanation of the Galaxy rotation curves in [50][51][52][53][54][55][56][57].…”

Constraining dark matter with gravitational waves from supermassive black hole binaries using Cassini data

“…In this so-called modified gravity theory or modified Newtonian dynamics, Einstein's field equations or Newton's law of gravitation are modified to explain successfully the aforementioned observations 3 (cf. [10], [11]) and other phenomena [12].…”