# Compact objects in unimodular gravity

## TL;DR

This paper explores how unimodular gravity, which allows for non-conservation of energy-momentum, affects stellar structures, black hole limits, and gravitational collapse, revealing potential observable deviations from standard gravity.

## Contribution

It provides new insights into stellar and black hole solutions in unimodular gravity and examines the implications of energy-momentum non-conservation on astrophysical phenomena.

## Key findings

- Constant density objects can be as compact as Schwarzschild black holes.
- Modifications in polytropic objects due to non-conservation are significant and observable.
- Revisits the Reissner-Nordström solution within unimodular gravity.

## Abstract

Unimodular gravity provides a theoretical framework that allows for non-conservation of energy-momentum, with possible implications for the cosmological constant problem. It is then important to study the predictions of unimodular gravity in other gravitational regimes. In this work we study stellar dynamics under the assumption of non-conserved energy-momentum. We find that constant density objects can be as compact as Schwarzschild black holes. For polytropic objects, we find modifications due to the non-conservation of energy-momentum that lead to sizeable effects that could be constrained with observational data. Additionally, we revisit and clarify the Reissner-Nordstr\"om solution in unimodular gravity. We also study gravitational collapse and discuss possible implications for the growth of structure.