Friday, December 12, 2014

Tracking Satellite Halo Orbits

The final major new addition to v0.9.3 of Galacticus has just been added. This is the subhalo evolution code written by Anthony Pullen which was used in our recent work on the subhalo population in warm dark matter halos.

The new model is similar to previous works by Taylor & Babul (2001), Benson et al. (2002), and Zentner et al. (2005). It tracks the orbit of each subhalo directly, accounting for the gravitational potential of the host halo, dynamical friction, tidal mass loss, and tidal shocking, but ignoring subhalo-subhalo interactions to minimize the computational cost.

The result is that Galacticus can predict the radial and mass distributions of subhalos directly, without the need to extract these from N-body simulations. An example of the distribution of halos is shown below (image credit: Anthony Pullen):

Each circle represents a subhalo within a Milky Way-mass dark matter halo at z=0, with the radius indicating the current tidal radius of the subhalo.

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