The effect of pressure gradients on luminosity distance - redshift relations

Understand

Inhomogeneous cosmological models have had significant success in explaining cosmological observations without the need for dark energy.

• Generally, these models imply inhomogeneous matter distributions alter the observable relations that are taken for granted when assuming the Universe evolves according to the standard Friedmann equations.
• Moreover, it has recently been shown that both inhomogeneous matter and pressure distributions are required in both early and late stages of cosmological evolution.
• These associated pressure gradients are required in the early Universe to sufficiently describe void formation, whilst late-stage pressure gradients stop the appearance of anomalous singularities.