Nonconservative unimodular gravity: Gravitational waves

TL;DR

This paper investigates how gravitational waves evolve in nonconservative unimodular gravity, revealing potential observational differences from standard General Relativity due to the theory's unique geometric structure.

Contribution

It introduces the study of gravitational waves within nonconservative unimodular gravity, highlighting differences from General Relativity when energy-momentum conservation is not assumed.

Findings

Gravitational wave evolution differs from standard predictions.

Nonconservative unimodular gravity exhibits unique observational signatures.

Potential implications for gravitational wave detection and cosmology.

Abstract

Unimodular gravity is characterized by an extra condition with respect to General Relativity: the determinant of the metric is constant. This extra condition leads to a more restricted class of invariance by coordinate transformation. Even though, if the conservation of the energy-momentum tensor is imposed in unimodular gravity, the General Relativity theory is recovered with an additional integration constant which is associated to the cosmological term $\Lambda$. However, if the energy-momentum tensor does not conserve separately, a new geometric structure appears with potentially observational signatures. In this text, we consider the evolution of gravitational waves in the nonconservative unimodular gravity, showing how it differs from the usual signatures in the standard model.