/np_vpower

Nearest-particle velocity power spectrum code

Primary LanguageC++GNU General Public License v3.0GPL-3.0

np_vpower

np_vpower calculates velocity power spectrum of cosmological large-scale structure using the Nearest-particle method. The code reads N-body particles or haloes from a simulation in a periodic box.

Getting Started

  1. The code uses the FFTW3 library. Set the FFTW_DIR variable in the Makefile.

  2. The code also uses the BOOST library to read command line options, which is optional. Set the BOOST_DIR variable if necessary, or you can disable using comandline options by setting USE_BOOST_PROGRAM_OPTIONS = 0.

  3. Make

    $ make

  4. Run. This code reads Gadget binary file

    $ ./np_vpower --gadget-file snp > vpower.txt

where snp is the name of the snapshot file. Modify read_fof_text function in halo_file.cpp to read your own files of dark matter particles or haloes.

Command-line Options

You can change the parameters by setting command-line options

   $ ./np_vpower [options] <filename>
  • --nc=128 : Set the number of grids for the Fourier Transform.
  • --dk=0.01 : Set dk to change output k binning
  • --kmax=1.0 : Set kmax to fix the value of maximum k in the output

The code calculates power spectra in real space by default. Set

  • --reddshift-space

for power spectra in redshift space.

The code also calculates momentum power spectrum:

  • --momentum-power

Simulation parameters are read from Gadget file, but if you read FoF halo data from an ascii file, you need to give simulation boxsize,

  • --boxsize=1000 : Box size in [/h Mpc]

You also need cosmological parameters for the redshift-space distortions for FoF data,

  • --omegam=0.273

which assumes flat LambdaCDM (omega_lambda= 1 - omegam).

You can select haloes in a mass range, log10(M) in [logMmin, logMmax], using,

  • --m=7.5e11 : Particle mass
  • --logMmin=12.0 : log10[Mmin/(1/h Solar mass)]
  • --logMmax=13.0

See a brief description of options by running the code without arguments,

   $ ./np_vpower

Authors

This code is written by Jun Koda.

  1. Koda et al. 2013, Are peculiar velocity surveys competitive as a cosmological probe?, MNRAS, 445, 4267 NASA ADS arXiv:1312.1022.

Please reference this paper if you use this code for scientific works.

Licence

This code is distributed under the GPLv3 license.