Ellipsoidal universe in the brane world

TL;DR

This paper explores the evolution of an ellipsoidal universe within brane world cosmology, analyzing how anisotropy from magnetic fields and brane-induced gravity influence eccentricity decay and its implications for cosmic microwave background anomalies.

Contribution

It derives coupled evolution equations for eccentricity and scale factor in brane world scenarios, including effects of magnetic fields and brane-induced gravity, extending previous four-dimensional models.

Findings

Eccentricity decays faster in the bulk than in 4D models.

Magnetic fields influence the anisotropy evolution.

Eccentricity may help explain the CMB quadrupole anomaly.

Abstract

We study a scenario of the ellipsoidal universe in the brane world cosmology with a cosmological constant in the bulk . From the five-dimensional Einstein equations we derive the evolution equations for the eccentricity and the scale factor of the universe, which are coupled to each other. It is found that if the anisotropy of our universe is originated from a uniform magnetic field inside the brane, the eccentricity decays faster in the bulk in comparison with a four-dimensional ellipsoidal universe. We also investigate the ellipsoidal universe in the brane-induced gravity and find the evolution equation for the eccentricity which has a contribution determined by the four- and five-dimensional Newton's constants. The role of the eccentricity is discussed in explaining the quadrupole problem of the cosmic microwave background.