Are we living near the center of a local void?

Abstract

The properties of the cosmic microwave background (CMB) temperature and polarisation anisotropies measured by a static, off-centered observer located in a local spherically symmetric void, are described. In particular in this paper we compute, together with the standard 2- point angular correlation functions, the off-diagonal correlators, which are no more vanishing by symmetry. While the energy shift induced by the off-centered position of the observer can be suppressed by a proper choice of the observer velocity, a lensing-like effect on the CMB emission point remains. This latter effect is genuinely geometrical (e.g. non-degenerate with a boost) and reflects in the structure of the off-diagonal correlators. At lowest order in this effect, the temperature and polarisation correlation matrices have non-vanishing diagonal elements, as usual, and all the off-diagonal terms are excited. This particular signature of a local void model allows one, in principle, to disentangle geometrical effects from local kinematical ones in CMB observations.

49 pages, 8 figures

References in corpus (4)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results
• Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
• The Signature of Proper Motion in the Microwave Sky
• Aberration of the Cosmic Microwave Background

Cited by in corpus (8)

• Doppler boosting the stochastic gravitational wave background
• Two-point Correlation Functions in Inhomogeneous and Anisotropic Cosmologies
• CMB sky for an off-center observer in a local void I: framework for forecasts
• Aberration of gravitational waveforms by peculiar velocity
• Boosting gravitational waves: a review of kinematic effects on amplitude, polarization, frequency and energy density
• Cosmic voids and induced hyperbolicity. II. Sensitivity to void/wall scales
• Cosmic voids and induced hyperbolicity. III. tracing redshift dependence
• Light propagation in linearly perturbed $\Lambda$LTB models