Constraining Curvature in Kantowski-Sachs Spacetimes with Late Time Anisotropy

The current standard model of cosmology postulates that any large-scale spatial curvature the Universe possesses is isotropic. However, it is possible for space to possess anisotropic curvature, and such spaces remain viable candidates for describing the large-scale spacetime structure of the Universe. Here we seek to constrain the anisotropic curvature of a Kantowski-Sachs universe, a model admitting an S² × E¹ spatial geometry. By solving the Einstein equations with small scale factor anisotropy, we model the expansion of this universe from last scattering onwards and examine the consequences of this anisotropic evolution on cosmological observables. We find that the anisotropic curvature of a Kantowski-Sachs universe is constrained by the quadrupole ampltiude of the cosmic microwave background.