Open AccessThe evolution of substructure in galaxy, group and cluster haloes – I. Basic dynamics
Author(s) -
Taylor James E.,
Babul Arif
Publication year - 2004
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.1365-2966.2004.07395.x
Subject(s) - substructure , physics , halo , astrophysics , merge (version control) , galaxy , virial theorem , galaxy formation and evolution , radius , cluster (spacecraft) , dark matter , satellite galaxy , structure formation , astronomy , computer security , structural engineering , computer science , engineering , information retrieval , programming language
The hierarchical mergers that form the haloes of dark matter surrounding galaxies, groups and clusters are inefficient, leaving substantial amounts of dense substructure, in the form of stripped halo cores or ‘subhaloes’, orbiting within these systems. Using a semi‐analytic model of satellite dynamics, we study the evolution of haloes as they merge hierarchically, to determine how much substructure survives merging and how the properties of individual subhaloes change over time. We find that subhaloes evolve, owing to mass loss, orbital decay and tidal disruption, on a characteristic time‐scale equal to the period of radial oscillations at the virial radius of the system. Subhaloes with realistic densities and density profiles lose 25–45 per cent of their mass per pericentric passage, depending on their concentration and on the circularity of their orbit. As the halo grows, the subhalo orbits also grow in size and become less bound. Based on these general patterns, we suggest a method for including realistic amounts of substructure in semi‐analytic models based on merger trees. We show that the parameters in the resulting model can be fixed by requiring self‐consistency between different levels of the merger hierarchy. In a companion paper, we will compare the results of our model with numerical simulations of halo formation.