Open AccessEffects of dynamical evolution on the distribution of substructures
Author(s) -
Peñarrubia Jorge,
Benson Andrew J.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09633.x
Subject(s) - substructure , physics , dark matter , mass distribution , dynamical friction , gravitational potential , milky way , halo , astrophysics , gravitation , classical mechanics , galaxy , structural engineering , engineering
We develop a semi‐analytical model that determines the evolution of the mass and position of dark matter substructures orbiting in dark matter haloes. We apply this model to the case of the Milky Way. We focus in particular on the effects of mass loss, dynamical friction and substructure–substructure interactions, the last of which has previously been ignored in analytic models of substructure evolution. Our semi‐analytical treatment reproduces both the spatial distribution of substructures and their mass function as obtained from the most recent N ‐body cosmological calculations of Gao et al. We find that, if mass loss is taken into account, the present distribution of substructures is practically insensitive to dynamical friction and scatterings from other substructures. Implementing these phenomena leads to a slight increase (≃5 per cent) in the number of substructures at r < 0.25 r vir , whereas their effects on the mass function are negligible. We find that mass‐loss processes lead to the disruption of substructures before dynamical friction and gravitational scattering can significantly alter their orbits. Our results suggest that the present substructure distribution at r > 0.25 r vir reflects the orbital properties at infall and is therefore purely determined by the dark matter environment around the host halo and has not been significantly altered by dynamical evolution.