2006/10/31 by John F. Beacom, John F Beacom
Computer Science · Physics and Astronomy · #Annihilation #Computational Physics and Python Applications #Cusp (singularity) #Dark Matter and Cosmic Phenomena #Dark fluid #Dark matter #Hot dark matter #Light dark matter #Neutrino #Particle physics theoretical and experimental studies #Scalar field dark matter #Universe #astro-ph #hep-ph #nucl-th
paper · pdf · doi:10.1088/1742-6596/60/1/037
published in Journal of Physics Conference Series 60, 183-186 (IOP Publishing) · 4 pages, 2 figures; to appear in the proceedings of the TeV Particle Astrophysics II Workshop, Madison, Wisconsin, 28-31 Aug 2006
arxiv created 2006/10/31 · openalex publication_date 2007/03/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
How large can the dark matter self-annihilation rate in the late universe be? This rate depends on (ρ DM /m χ ) 2 ⟨σA v ⟩, where ρ DM /m χ is the number density of dark matter, and the annihilation cross section is averaged over the velocity distribution. Since the clustering of dark matter is known, this amounts to asking how large the annihilation cross section can be. Kaplinghat, Knox, and Turner proposed that a very large annihilation cross section could turn a halo cusp into a core, improving agreement between simulations and observations; Hui showed that unitarity prohibits this for large dark matter masses. We show that if the annihilation products are Standard Model particles, even just neutrinos, the consequent fluxes are ruled out by orders of magnitude, even at small masses. Equivalently, to invoke such large annihilation cross sections, one must now require that essentially no Standard Model particles are produced.