Anticipating a new physics signal in upcoming 21-cm power spectrum observations
Rennan Barkana, Anastasia Fialkov, Hongwan Liu, Nadav Joseph Outmezguine
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 3 orders of magnitude larger than expected in $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ 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.