Modified dispersion relations and a potential explanation of the EDGES anomaly

TL;DR

This paper investigates whether modified dispersion relations, arising from theories of quantum gravity, can explain the anomalously strong 21-cm absorption signal detected by EDGES, suggesting new physics beyond standard cosmology.

Contribution

It proposes a novel explanation for the EDGES anomaly using modified dispersion relations from quantum gravity theories, linking fundamental physics to cosmological observations.

Findings

Modified dispersion relations alter the CMB photon spectrum.

The proposed model can account for the enhanced 21-cm absorption.

Potential connection between quantum gravity effects and cosmological anomalies.

Abstract

The Experiment to Detect the Global Epoch of Reionisation Signature (EDGES) collaboration has recently reported an important result related to the absorption signal in the Cosmic Microwave Background radiation spectrum. This signal corresponds to the red-shifted 21-cm line at $z \simeq 17.2$, whose amplitude is about twice the expected value. This represents a deviation of approximately $3.8\sigma$ from the predictions of the standard model of cosmology, i.e. the $\Lambda$CDM model. This opens a window for testing new physics beyond both the standard model of particle physics and the $\Lambda$CDM model. In this work, we explore the possibility of explaining the EDGES anomaly in terms of modified dispersion relations. The latter are typically induced in unified theories and theories of quantum gravity, such as String/M-theories and Loop Quantum Gravity. These modified dispersion relations affect the density of states per unit volume and thus the thermal spectrum of the Cosmic Microwave Background photons. The temperature of the 21-cm brightness temperature is modified accordingly giving a potential explanation of the EDGES anomaly.