David Cole, Walter Dehnen, Mark WilkinsonUniversity of Leicester

Dark Matter in clusters, groups and galaxiesNottingham-Birmingham extragalactic

workshopNottingham 14/15 September 2011

The cusp/core problem

log radius

Navarro, Frenk & White 1997 Navarro et al 2010

Observations

Oh et al 2008IC 2574

Analytical model

Parabolic orbit

Final halo mass model 1

Final halo mass model 2

Fiducial runs

t

Effects on the dark matter halo

r

Halo shape

r r

Anisotropy

r

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

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).

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.

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.

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

Sinking clumps – minor mergers

Hubble Interacting Galaxy NGC 695

Hubble Interacting Galaxy IRAS F10565

Conclusions

Sinking clumps can modify the cuspParabolic orbits have a stronger effectSmaller clumps are more effectiveHalo shape and velocity structure changedExpulsion of the clump material produces

an even greater effect