2020/09/30 by Cosmin Ilie, Caleb Levy, Jacob Pilawa +2
Physics and Astronomy · #Astronomy #Astrophysics #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark matter #Formalism (music) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Physics #Population #Redshift #Sigma #Star (game theory) #Star formation #Stars #astro-ph.CO #hep-ph
paper · pdf · doi:10.1103/physrevd.104.123031
20 pages, 8 figures, final version published to PRD; Revised: included analyses on the proton-DM cross sections for sub-GeV DM models; expanded discussion on ambient DM densities ; included the effect of the "annihilation plateau"; we added three appendices (dark matter temperature, approximations for DM evaporation rates, and equilibria requirements between capture and annihilation/evaporation)
openalex publication_date 2021/12/22 · arxiv created 2022/02/15 · arxiv updated 2022/02/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Dark matter (DM) can be trapped by the gravitational field of any star, since collisions with nuclei in dense environments can slow down the DM particle below the escape velocity (vesc) at the surface of the star. If captured, the DM particles can self-annihilate, and, therefore, provide a new source of energy for the star. We investigate this phenomenon for capture of DM particles by the first generation of stars [Population III (Pop III) stars], by using the multiscatter capture formalism. Pop III stars are particularly good DM captors, since they form in DM-rich environments, at the center of \ensuremath∼106 M_\ensuremath\bigodot DM minihalos, at redshifts z\ensuremath∼15. Assuming a DM-proton scattering cross section (\ensuremathσ) at the current deepest exclusion limits provided by the XENON1T experiment, we find that captured DM annihilations at the core of Pop III stars can lead, via the Eddington limit, to upper bounds in stellar masses that can be as low as a few M_\ensuremath\bigodot if the ambient DM density (\ensuremathρX) at the location of the Pop III star is sufficiently high. Conversely, when Pop III stars are identified, one can use their observed mass (M_\ensuremath⋆) to place bounds on \ensuremathρX\ensuremathσ. Using adiabatic contraction to estimate the ambient DM density in the environment surrounding Pop III stars, we place projected upper limits on \ensuremathσ, for M_\ensuremath⋆ in the 100 M_\ensuremath\bigodot--1000 M_\ensuremath\bigodot range, and find bounds that are competitive with, or deeper than, those provided by the most sensitive current direct detection experiments for both spin-independent and spin-dependent (SD) interactions, for a wide range of DM masses. Most intriguingly, we find that Pop III stars with mass M_\ensuremath⋆\ensuremath\gtrsim300 M_\ensuremath\bigodot could be used to probe the SD proton-DM cross section below the ``neutrino floor,'' i.e. the region of parameter space where DM direct detection experiments will soon become overwhelmed by neutrino backgrounds.