Cosmological observations in a modified theory of gravity (MOG)

TL;DR

This paper explores the potential of a modified gravity theory (MOG) to explain cosmological observations without dark matter, showing promising results in modeling matter distribution and cosmic microwave background features.

Contribution

It demonstrates that MOG can model cosmological phenomena like matter power spectrum and CMB acoustic peaks, providing an alternative to dark matter-based models.

Findings

MOG agrees with observed matter power spectrum at present

Oscillations in MOG's power spectrum are not suppressed without dark matter

MOG can potentially model the CMB acoustic spectrum peak

Abstract

Our modified gravity theory (MOG) is a gravitational theory without exotic dark matter, based on an action principle. MOG has been used successfully to model astrophysical phenomena such as galaxy rotation curves, galaxy cluster masses, and lensing. MOG may also be able to account for cosmological observations. We assume that the MOG point source solution can be used to describe extended distributions of matter via an appropriately modified Poisson equation. We use this result to model perturbation growth in MOG and find that it agrees well with the observed matter power spectrum at present. As the resolution of the power spectrum improves with increasing survey size, however, significant differences emerge between the predictions of MOG and the standard LCDM model, as in the absence of exotic dark matter, oscillations of the power spectrum in MOG are not suppressed. We can also use MOG to model the acoustic power spectrum of the cosmic microwave background. A suitably adapted semi-analytical model offers a first indication that MOG may pass this test, and correctly model the peak of the acoustic spectrum.