ETHOS ‐ an effective theory of structure formation: Impact of dark acoustic oscillations on cosmic dawn

Abstract

Upcoming data of the 21-cm hydrogen line during cosmic dawn (z ∼ 10-30) will revolutionize our understanding of the astrophysics of the first galaxies. Here we present a case study on how to exploit those same measurements to learn about the nature of dark matter (DM) at small scales. Focusing on the effective theory of structure formation (ETHOS) paradigm, we run a suite of simulations covering a broad range of DM microphysics, connecting the output of N-body simulations to dedicated 21-cm simulations to predict the evolution of the 21-cm signal across the entire cosmic dawn. We find that observatories targeting both the global signal and the 21-cm power spectrum are sensitive to all ETHOS models we study, and can distinguish them from CDM if the suppression wave number is smaller than k ≈ 300 h=Mpc, even when accounting for feedback with a phenomenological model. This is an order of magnitude smaller comoving scales than currently constrained by other datasets, including the Lyman-α forest. Moreover, if a prospective 21-cm detection confirmed a deficiency of power at small scales, we show that ETHOS models with strong dark acoustic oscillations can be discriminated from the pure suppression of warm dark matter, showing the power of 21-cm data to understand the behavior of DM at the smallest physical scales.

Snowmass2021 Cosmic Frontier White Paper: Dark Matter Physics from Halo Measurements

“…8. As a consequence, it will probe fuzzy or self-interacting DM beyond the reach of the global signal [567,568].…”

Dark matter-baryon scattering effects on temperature perturbations and implications for cosmic dawn

“…This suppression occurs at the scales of interest for the formation of the dark matter halos that could host the first stars. Therefore, the DM-baryon interactions may delay cosmic dawn even more than originally predicted by first estimates that neglected the contributions to the temperature perturbations, which should have a very strong impact in the HI line-intensity mapping observables during cosmic dawn [32][33][34][35][36][37][38][39][40]. Moreover, the modified temperature perturbations may induce additional spatial correlations in the clustering of the first stars.…”

“…While post-reionization measurements are promising in this regard (see e.g., [30,31]), the HI intensity mapping signal from cosmic dawn is expected to be especially sensitive to the DM microphysics. In general, any model with clustering suppression at small scales delays the collapse of the first halos and therefore the formation of the first stars, affecting the time evolution of cosmic dawn and reionization [32][33][34][35][36][37][38][39][40]. Furthermore, since the HI signal is highly sensitive to the gas temperature through the HI spin temperature, any modification to the gas temperature (either due to energy injection or heat transfer) is expected to greatly modify the HI signal [41][42][43][44][45][46][47][48][49].…”

Astrophysical and Cosmological Probes of Dark Matter

“…While there are claims that the global (sky-averaged) signal has already been detected [493], the tomographic signal is yet to be measured [494] from interferometers such as HERA [509], LOFAR, MWA, or SKA [510]. However, it is expected that these observatories can yield constraints on the matter power spectrum up to k = 100 Mpc −1 at the ∼ 10% level [508], which can place powerful constraints on specific dark matter candidates such as ETHOS models [511], warm dark matter [512], or fuzzy dark matter [513].…”