Future 21cm constraints on dark matter energy injection: Application to ALPs

TL;DR

This paper explores how future 21cm cosmology observations, especially with HERA, can significantly improve constraints on decaying dark matter and axion-like particles, probing new parameter space beyond current methods.

Contribution

It presents the first Fisher matrix forecasts for HERA's sensitivity to dark matter energy injection, focusing on ALPs in the 10 keV to 1 MeV mass range, demonstrating potential for unprecedented constraints.

Findings

HERA can improve constraints on dark matter decay by up to three orders of magnitude.

21cm power spectrum measurements can probe ALP parameter space beyond existing searches.

Future 21cm observations will help explore uncharted dark matter regions.

Abstract

The redshifted 21cm signal from the Cosmic Dawn is expected to provide unprecedented insights into early Universe astrophysics and cosmology. Here, we briefly summarize how decaying dark matter can heat the intergalactic medium before the first galaxies, leaving a distinctive imprint on the 21cm power spectrum. We discuss the first Fisher matrix forecasts on the sensitivity of the Hydrogen Epoch of Reionization Array telescope (HERA) and argue that HERA can improve by up to three orders of magnitude previous cosmology constraints. In these proceedings, we project these future bounds in the plane of the Axion like particles (ALP) coupling to photons as a function of the ALP mass. We focus on the ALP mass range between $\sim$ 10 keV and 1 MeV where the 21cm signal power spectrum probes are expected to improve on any other current dark matter searches. This illustrates how 21cm cosmology can be expected to help in probing uncharted regions of the dark matter parameter space beyond the reach of existing astro-particle and cosmology experiments.