Amirhossein Samandar - Navigating Cosmic Topology's Effects on CMB Polarization скачать в хорошем качестве

Amirhossein Samandar - Navigating Cosmic Topology's Effects on CMB Polarization

Abstract: "The standard cosmological model, which assumes statistical isotropy and parity invariance, predicts the absence of correlations between even-parity and odd-parity observables of the cosmic microwave background (CMB). However, large-angle CMB temperature anomalies and recent findings of non-zero equal-\ell \EB correlations in CMB polarization challenge these expectations. These anomalies suggest possible deviations from statistical isotropy, parity violations, or both. Cosmic topology, which modifies only the boundary conditions of space without altering the fundamental physics, offers a framework that could explain these parity-breaking observations. Topology inherently breaks statistical isotropy, and can also break homogeneity and parity, providing a natural paradigm for explaining observations of parity-breaking observables without the need to add parity violation to the underlying microphysics. Our investigation delves into the harmonic space implications of topology for CMB correlations, using as an illustrative example \EB correlations generated by tensor perturbations under both parity-preserving and parity-violating scenarios. Consequently, these findings not only challenge the foundational assumptions of the standard cosmological model but also open new avenues for exploring the topological structure of the Universe through CMB observations."