Seventeenth Marcel Grossmann Meeting

Assessing the significance of CMB anomalies with cosmological gravitational waves

9 Jul 2024, 17:30

30m

Tosti (Aurum)

Invited talk in a parallel session Current Status of the H_0 and growth tensions: theoretical models and model-independent constraints Current status of the H_0 and growth tensions: theoretical models and model-independent constraints

Speaker

Giacomo Galloni (University of Ferrara)

Description

Since the very first observations, the Cosmic Microwave Background (CMB) has revealed on large scales unexpected features known as anomalies, which challenge the standard $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }$CDM) cosmological model. One of these is the hemispherical power asymmetry, i.e. a difference in the average power on the two hemispheres centered around (l, b) = (221, −20), which shows a relatively high level of significance. Another is the lack-of-correlation, where the measured two-point angular correlation function of CMB temperature anisotropies is compatible with zero, differently from the predictions of the standard model. These anomalies could indicate a deviation from the standard model, unknown systematics, or simply a rare realization of the model itself. In this talk, I will investigate the physical origin of these anomalies, leveraging the potential information provided by the cosmological gravitational wave background (CGWB) detectable by future gravitational wave (GW) interferometers. In particular, I will analyze both constrained and unconstrained realizations of the CGWB to study the extent of information that GWs can offer. Indeed, the CGWB represents a unique window to explore the early universe and I will show that it can be used in combination with CMB data to shed light on the CMB anomalies.

Proceedings

Paper

MG17_Galloni_proceeding.pdf