Anticipating a New-Physics Signal in Upcoming 21-cm Power Spectrum Observations

TL;DR

This paper predicts a distinctive 21-cm power spectrum signal caused by dark matter-baryon interactions in a two-component dark sector, which could be detected by upcoming experiments to test new physics beyond standard cosmology.

Contribution

It introduces a novel model with a millicharged dark matter component that produces a detectable 21-cm power spectrum signal with acoustic oscillations.

Findings

Signal can be up to 1000 times larger than in ΛCDM

Produces distinctive acoustic oscillations in the 21-cm power spectrum

Near-future experiments can test this dark matter model

Abstract

Dark matter-baryon interactions can cool the baryonic fluid, which has been shown to modify the cosmological 21-cm global signal. We show that in a two-component dark sector with an interacting millicharged component, dark matter-baryon scattering can produce a 21-cm power spectrum signal with acoustic oscillations. The signal can be up to three orders of magnitude larger than expected in $\Lambda$CDM cosmology, given realistic astrophysical models. This model provides a new-physics target for near-future experiments such as HERA or NenuFAR, which can potentially discover or strongly constrain the dark matter explanation of the putative EDGES anomaly.