http://arxiv.org/abs/2209.11237
Dark matter is the dominant form of matter in today’s universe. Its gravitational effects drive the formation of galaxies and all larger structure, yet its nature is unknown. As gravitational collapse creates the first cosmic objects, a dark matter cusp forms immediately at every initial density maximum. Such prompt cusps have a density profile $\rho\propto r^{-1.5}$ extending up to a limiting density dependent on the nature of the dark matter. Numerical simulations and theoretical arguments suggest that the bulk of these cusps survive until the present day. Here we show that if dark matter is a thermally produced weakly interacting massive particle, many thousands of prompt cusps with individual masses similar to that of the earth should be present in every solar mass of dark matter. This radically alters predictions for the amount and spatial distribution of dark matter annihilation radiation, substantially tightening observational constraints on the relevant cross sections. In particular, the cross section required to explain the observed $\gamma$-ray excess near the Galactic Centre predicts prompt cusp emission from the Milky Way’s outer halo and from extragalactic dark matter at levels in tension with the observed diffuse $\gamma$-ray background.
M. Delos and S. White
Mon, 26 Sep 22
27/62
Comments: 19 pages, 10 figures; submitted
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