Dark Photons in the Radio Sky: II. Resonant Conversions in the Intergalactic Medium

TL;DR

This paper evaluates how the Square Kilometre Array and 21-cm experiments can detect dark photons through resonant conversions in the intergalactic medium, potentially revealing new physics beyond the Standard Model.

Contribution

It provides a detailed analysis pipeline for SKA's sensitivity to dark photons via resonant conversions in the intergalactic medium, including the impact on temperature anisotropies.

Findings

SKA and 21-cm experiments can detect dark photons with masses between 5×10^{-15} and 5×10^{-12} eV.

Sensitivity to the kinetic mixing parameter ε can reach as low as 10^{-8}.

Potential for discovery of dark photons in the specified mass and mixing range.

Abstract

This is the second part in a pair of papers forecasting the sensitivity of the Square Kilometre Array (SKA) to dark photons, a highly motivated, simple extension of the Standard Model. Through a kinetic mixing term, visible photons from the cosmic microwave background can resonantly convert into dark photons, generating new temperature anisotropies in the sky. In this work, we detail the entire analysis pipeline that we use to compute SKA's sensitivity, focusing on resonant conversions that occur in the intergalactic medium. We also discuss the sensitivity of 21-cm experiments to dark photons. Our results show that both SKA in combination with galaxy surveys and 21-cm experiments could discover dark photons with masses between $5\times 10^{-15}$ and $5\times 10^{-12}$ eV, and kinetic mixing parameter $\epsilon$ as low as $10^{-8}$.