Galactic rotation dynamics in modified gravity

Abstract

In this thesis galactic rotation curves in f (T) gravity are investigated. Throughout this work T represents a torsional quantity. The study centers on the particular Lagrangian f (T) = T + aTn, where [n] = 1 is a real number and a is a small unknown constant. To achieve this, galactic rotation curves are treated as being composed from the contributions of two distinct features of galaxies, namely the disk and the bulge. This process is carried out for several values of the index n. The resulting curve is then compared with Milky Way profile data to constrain the value of n while fitting for the parameter a. On the galactic scale it is found that f(T) gravity departs from Einstein's standard general relativistic theory in an important way. For a small range of values of n we find good agreement with data without the need for exotic matter components to be introduced.