The virial theorem in Eddington-Born-Infeld gravity

TL;DR

This paper explores Eddington-Born-Infeld gravity as an alternative to dark matter by deriving a modified virial theorem that accounts for a geometrical mass, potentially explaining galaxy cluster mass discrepancies.

Contribution

It derives a generalized virial theorem within EBI gravity, introducing a geometrical mass term that can explain galaxy cluster mass discrepancies without dark matter.

Findings

The geometrical mass accounts for the virial mass discrepancy.

Derived velocity dispersion relation for galaxies in clusters.

Provides a testable prediction for EBI gravity using astrophysical data.

Abstract

We consider the possibility that the Eddington-Born-Infeld (EBI) modified gravity provides an alternative explanation for the mass discrepancy in clusters of galaxies. For this purpose we derive the modified Einstein field equations, finding an additional "geometrical mass" term which provides an effective contribution to the gravitational binding energy. Using some approximations and assumptions for weak gravitational fields, and taking into account the collisionless relativistic Boltzmann equation, we derive a generalized version of the virial theorem in the framework of EBI gravity. We show that the "geometrical mass" term may account for the well known virial mass discrepancy in clusters of galaxies. We also derive the velocity dispersion relation for galaxies in the clusters, which could provide an efficient method for testing EBI gravity from astrophysical observations.