Galactic Rotation Dynamics in f(T) gravity

TL;DR

This paper explores how a specific $f(T)$ gravity model can explain galactic rotation curves without dark matter, fitting data from multiple galaxies and constraining model parameters.

Contribution

It introduces a particular $f(T)$ gravity model with a power-law term and demonstrates its ability to fit galactic rotation data without exotic matter.

Findings

$f(T)$ gravity can match galactic rotation curves without dark matter.

The model constrains the power-law index $n$ based on Milky Way data.

Good fits are achieved for specific $n$ values across different galaxy types.

Abstract

We investigate galactic rotation curves in $f(T)$ gravity, where $T$ represents a torsional quantity. Our study centers on the particular Lagrangian $f(T)=T+\alpha{T^n}$, where $|n|\neq 1$ and $\alpha$ is a small unknown constant. To do this we treat galactic rotation curves as being composed from 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 the index $n$ while fitting for the parameter $\alpha$. These values are then further tested on three other galaxies with different morphologies. On the galactic scale we find that $f(T)$ gravity departs from standard Newtonian 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.