# Testing Emergent Gravity with Isolated Dwarf Galaxies

## TL;DR

This paper tests the predictions of Emergent Gravity, a modified gravity theory, against observed rotation curves of isolated dwarf galaxies, extending the theory to axisymmetric systems and analyzing its accuracy.

## Contribution

It extends Emergent Gravity equations to axisymmetric systems and performs the first rotation curve test using a large sample of isolated dwarf galaxies.

## Key findings

- EG predicts velocities well around 100 km/s
- EG underpredicts velocities for larger dwarfs
- EG overpredicts velocities for smaller dwarfs

## Abstract

Verlinde (2016) has proposed a new modified theory of gravity, Emergent Gravity (EG), as an alternative to dark matter. EG reproduces the Tully-Fisher relationship with no free parameters and agrees with the velocity curves of most massive, spiral galaxies well. In its current form, the theory only applies to isolated, spherically symmetric systems in a dark energy-dominated Universe, and thus can only be tested fairly with such systems. This paper presents a framework for rotation curve tests of EG using isolated dwarf galaxies. Here I extend the EG equations to axisymmetric distributions for the first time. I also perform a preliminary test of the predictions from EG versus the maximum velocity measurements of 452 isolated dwarf galaxies. I find that EG predicts the maximum velocities of these systems somewhat well for galaxies with measured velocities around $100~\rm{km/s}$. EG severely underpredicts the maximum velocities for dwarf galaxies with measured velocities greater than this value and overpredicts for those with measured velocities less than this value. Rotation curves of these isolated dwarf galaxies would provide the definitive test of EG.