Rennan Barkana

Abstract It is thought that the Universe went through an early period known as the Dark Ages, during which primeval density fluctuations grew to form the first luminous objects, marking the beginning of cosmic dawn around 100 million years after the Big Bang. The 21-cm line of hydrogen atoms is the most promising probe of these epochs, with extensive observational efforts underway.

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 ΛCDM cosmology, given realistic astrophysical models.

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