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Weakening dark matter cusps by clumpy baryonic infall

Weakening dark matter cusps by clumpy baryonic infall. David Cole, Walter Dehnen, Mark Wilkinson University of Leicester Dark Matter in clusters, groups and galaxies Nottingham-Birmingham extragalactic workshop Nottingham 14/15 September 2011. The cusp/core problem. log density.

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Weakening dark matter cusps by clumpy baryonic infall

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  1. Weakening dark matter cusps by clumpy baryonic infall David Cole, Walter Dehnen, Mark Wilkinson University of Leicester Dark Matter in clusters, groups and galaxies Nottingham-Birmingham extragalactic workshop Nottingham 14/15 September 2011

  2. The cusp/core problem log density log radius Navarro, Frenk & White 1997 Navarro et al 2010

  3. Observations Oh et al 2008 IC 2574

  4. Analytical model Final halo mass model 1 Final halo mass model 2 Parabolic orbit

  5. Fiducial runs t

  6. Effects on the dark matter halo r

  7. Halo shape r r

  8. Anisotropy r

  9. Satellite orbits Time evolution of the orbits of satellites representing baryonic clumps for four parabolic satellite orbits decaying in a dark matter halo with isotropic velocity distribution.

  10. Effect on Dark Matter Halo Radial profiles of the halo’s pseudo phase-space density ρ/σ3 (top), density ρ (middle), and the change in cumulative halo mass ΔM (bottom) at the end of the simulations shown in the previous slide (colour coding the same).

  11. Effect of the Removal of the satellite Radial profiles of the halo’s pseudo phase-space density ρ/σ3 (top), density ρ (middle), and the change in cumulative halo mass ΔM (bottom) for one of the satellites shown in the previous slide but also including the removal of the satellite.

  12. Effect of satellite Mass The variation with satellite mass of time to fall in,tinfall, ΔMmax, rmax, r50%, and the maximum of ρ/σ3 after the decay of a circular satellite orbit (red) or after the decay of a parabolic satellite orbit (blue). The lines are power-laws with exponent as indicated.

  13. Effect of satellite Size As previous slide, except that satellite size rs is varied and ms = 0.01 kept constant.

  14. Sinking clumps – minor mergers Hubble Interacting Galaxy IRAS F10565 Hubble Interacting Galaxy NGC 695

  15. Conclusions • Sinking clumps can modify the cusp • Parabolic orbits have a stronger effect • Smaller clumps are more effective • Halo shape and velocity structure changed • Expulsion of the clump material produces an even greater effect

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