CMB sky for an off-center observer in a local void I: framework for forecasts

Understand

The Universe is not perfectly homogeneous, the large scale structure forms overdense regions and voids.

• In this paper, we consider the possibility that we occupy a special position in our Universe, close to the center of a local underdense region that we model as an LTB void embedded in a homogeneous and isotropic Universe.
• The CMB sky measured by an off-center observer in this void is not statistically isotropic.
• In addition to the non-stochastic CMB anisotropies due to the geometry of the model, we also observe a lensing-like distortion of the CMB anisotropies.