HALOGEN is a C program for creating realistic synthetic dark matter halo catalogs in a flash.

It uses a statistical approach for generating the masses of the halos from a parameterised halo mass distribution, and placing them down in a spatial distribution with cheap 2LPT field as scaffolding.

HALOGEN has no external code dependencies, and therefore, compiling is as simple as typing make in the top-level directory of the desired version.

The program will be compiled into the same top-level directory as halogen.

To optionally install, save halogen somewhere on the system path, eg. in /usr/bin/.

To run HALOGEN, type halogen <input.file>.

An example input file is found in the input/ subdirectory of each version.

Notably, several files must be provided to the input:

• 2LPT file: A gadget file, which is output of the 2LPT run. This could also be the output of a full NBODY run with gadget.

• Output file: A file in which the output halo masses and positions will be written.

• alpha-file: A file containing a table of M and alpha, which encodes the relative biasing of halos of different masses. For constant bias, this should be one row long.

• hmf file: A file specifying the tabulated mass function with columns m,n(>m). This file can be generated in any way, but is most easily done with the native support at hmf.icrar.org

This code will soon have a paper to cite. For now, just let us know you are using the code.

Santiago Avila Perez: santiago.avila@uam.com Steven Murray: steven.murray@uwa.edu.au