paper

Dark Matter Bars in Spinning Halos

arXiv:1811.00033 · doi:10.1093/mnras/stz2144

Abstract

We study nonlinear response of spinning dark matter (DM) halos to dynamic and secular evolution of stellar bars in the embedded galactic disks, using high-resolution numerical simulations. For a sequence of halos with the cosmological spin parameter lambda=0-0.09, and a representative angular momentum distribution, we analyze evolution of induced DM bars amplitude and quantify parameters of the response as well as trapping of DM orbits and angular momentum transfer by the main and secondary resonances. We find that (1) maximal amplitude of DM bars depends strongly on `lambda', while that of the stellar bars is indifferent to `lambda'; (2) Efficiency of resonance trapping of DM orbits by the bar increases with `lambda', and so is the mass and the volume of DM bars; (3) Contribution of resonance transfer of angular momentum to the DM halo increases with `lambda', and for larger spin, the DM halo `talks' to itself, by moving the angular momentum to larger radii --- this process is maintained by resonances; (4) Prograde and retrograde DM orbits play different roles in angular momentum transfer. The `active' part of the halo extends well beyond the bar region, up to few times the bar length in equatorial plane and away from this plane. (5) We model evolution of diskless DM halos and halos with frozen disks, and found them to be perfectly stable to any Fourier modes. Finally, further studies adopting a range of mass and specific angular momentum distributions of the DM halo will generalize the dependence of DM response on the halo spin and important implications for direct detection of DM and that of the associated stellar tracers, such as streamers.

MNRAS, in press, 15 pages, 12 figures

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