1. 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 radius log density Navarro, Frenk & White 1997Navarro et al 2010

3. Observations Oh et al 2008 IC 2574

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

5. Fiducial runs t

6. Effects on the dark matter halo r

7. Halo shape rr

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 halos pseudo phase- space density ρ/σ 3 (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 halos pseudo phase- space density ρ/σ 3 (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,t infall, ΔM max, r max, r50%, and the maximum of ρ/σ 3 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 r s is varied and m s = 0.01 kept constant.

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

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