Open AccessSatellite decay in flattened dark matter haloes
Author(s) -
Peñarrubia Jorge,
Kroupa Pavel,
Boily Christian M.
Publication year - 2002
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 - 10.1046/j.1365-8711.2002.05414.x
Subject(s) - physics , orbital plane , astrophysics , galaxy , satellite , satellite galaxy , astronomy , orbit (dynamics) , dark matter , orbital inclination , dark matter halo , rotational symmetry , halo orbit , orbital elements , halo , arithmetic , mathematics , binary number , mechanics , engineering , aerospace engineering
We carry out a set of self‐consistent N ‐body calculations to compare the decay rates of satellite dwarf galaxies orbiting a disc galaxy embedded in a dark matter halo (DMH). We consider both spherical and oblate axisymmetric DMHs of aspect ratio q h =0.6 . The satellites are given different initial orbital inclinations, orbital periods and mass. The live flattened DMHs with embedded discs and bulges are set‐up using a new fast algorithm due to Boily, Kroupa & Peñarrubia called magalie . We find that the range of survival times of satellites within a flattened DMH becomes ∼100 per cent larger than the same satellites within a spherical DMH. In the oblate DMH, satellites on polar orbits have the longest survival time, whereas satellites on coplanar prograde orbits are destroyed most rapidly. The orbital plane of a satellite tilts as a result of anisotropic dynamical friction, causing the satellite's orbit to align with the plane of symmetry of the DMH. Polar orbits are not subjected to alignment. Therefore the decay of a satellite in an axisymmetric DMH may provide a natural explanation for the observed lack of satellites within 0–30° of their host galaxy's disc. The computations furthermore indicate that the evolution of the orbital eccentricity e is dependent on its initial value e ( t =0) and the DMH's shape. We also discuss some implications of flattened DMHs for satellite debris streams.