Astrophysics, abstract
astro-ph/0604142

From: Anne Green [view email]

Date: Thu, 6 Apr 2006 17:17:56 GMT (117kb)

Mini-halo disruption due to encounters with stars

Authors: Anne M. Green, Simon P. Goodwin

Comments: 10 pages, 7 figures

We study the energy loss and disruption of dark matter mini-halos due to interactions with stars. We find that the fractional energy loss in simulations agrees well with the analytic impulse approximation for small and large impact parameters, with a rapid transition between these two regimes. The fractional energy loss at large impact parameters is fairly independent of the mass and density profile of the mini-halo, however low-mass mini-halos lose a greater fraction of their energy in close encounters. We formulate new fitting functions that match these results and use them to estimate the disruption timescales, taking into account the stellar velocity and mass distributions. For mini-halos with mass $M< {\cal O}(10^{-7} M_{\odot})$ on typical orbits which pass through the disc, we find that the disruption timescales are independent of mass and of order the age of the Milky Way. For more massive mini-halos the disruption timescales increase rapidly with increasing mass. Finally, we point out that the fractional energy loss is dependent on the, somewhat arbitrary, definition of the mini-halo radius and argue that a full calculation of the mini-halo survival probability will have to incorporate energy loss due to encounters with stars and tidal stripping in a single consistent calculation.

http://xxx.lanl.gov/abs/astro-ph/0604142