Dynamical response of dark matter to galaxy evolution affects direct-detection experiments

2016/09/05 by Michael Petersen, Michael S. Petersen, Neal Katz +1
Physics and Astronomy · #Astronomy #Astrophysics #Cosmology #Cosmology and Gravitation Theories #Cuspy halo problem #Dark Matter and Cosmic Phenomena #Dark energy #Dark matter #Dark matter halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Galaxy rotation curve #Halo #Hot dark matter #Milky Way #Physics #Spiral galaxy #astro-ph.GA #hep-ph

paper · pdf · doi:10.1103/physrevd.94.123013

16 pages, 7 figures, submitted to Phys Rev D

arxiv created 2016/09/05 · openalex created_date 2016/09/16 · openalex publication_date 2016/12/27 · arxiv updated 2017/02/01 · openalex updated_date 2026/08/05

Abstract

Over a handful of rotation periods, dynamical processes in barred galaxies induce nonaxisymmetric structure in dark matter halos. Using n-body simulations of a Milky Way--like barred galaxy, we identify both a trapped dark matter component, a shadow bar, and a strong response wake in the dark matter distribution that affects the predicted dark matter detection rates for current experiments. The presence of a baryonic disk, together with well-known dynamical processes (e.g. spiral structure and bar instabilities), increases the dark matter density in the disk plane. We find that the magnitude of the combined stellar and shadow bar evolution, when isolated from the effect of the axisymmetric gravitational potential of the disk, accounts for >30% of this overall increase in disk-plane density. This is significantly larger than that of previously claimed deviations from the standard halo model. The dark matter density and kinematic wakes driven by the Milky Way bar increase the detectability of dark matter overall, especially for the experiments with higher v_min. These astrophysical features increase the detection rate by more than a factor of 2 when compared to the standard halo model and by a factor of 10 for experiments with high minimum recoil energy thresholds. These same features increase (decrease) the annual modulation for low (high) minimum recoil energy experiments. We present physical arguments for why these dynamics are generic for barred galaxies such as the Milky Way rather than contingent on a specific galaxy model.

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