Spherical Tests

These are the simplest tests: a suite of spherical one and two component galaxies. The files are available for download as Gadget format binary files. For information on reading/writing Gadget files, see file formats.

For all tests, the units are:

  • Graph
  • Graph
  • Graph

Single component models

We set up three isotropic single component models described by a simple “Dehnen” split power-law sphere, using the method described in Read et al. 2006:

Graph

where Graph is the total mass, Graph is the central asymptotic logarithmic slope, and Graph is the scale length. The parameters and data files are given in the following Table:

where Graph is the number of particles that for these single component models are stored in the dark matter array.

A million sample points is, of course, optimistic, but these can be simply down-sampled to represent a more realistic observational situation. Similarly, line of sight velocities can be used, rather than the full phase space information.

Multi component models

We set up three spherical isotropic multi-component models similarly to the single component models, above. These are double-Dehnen spheres with stars describing a tracer population of negligible mass and dark matter (with a different distribution function) describing the mass distribution. The properties are as follows:

Graph Graph Graph Graph Graph Graph Graph Graph file
1 1 0 Graph Graph 0.1 0 Graph dual_unit_hern_0.gad
1 1 1 Graph Graph 0.1 0 Graph dual_unit_hern_1.gad
1 1 2 Graph Graph 0.1 1 Graph dual_unit_hern_2.gad

Discussion

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