ltu-cmass

A repository for storing code for the LtU Express Go Big pipeline. The scripts in this repository are designed to simulate and analyze mocks of the CMASS NGC galaxy sample from the BOSS survey.

Pipeline

The minimal example of the pipeline using a pmwd simulation can be run using the following commands:

# Run nbody density fields
python -m cmass.nbody.pmwd

# Populate density fields with halos
python -m cmass.bias.rho_to_halo

# Remap the cube into a cuboid to match the survey volume
python -m cmass.survey.remap_cuboid

# Apply the survey mask to the cuboid
python -m cmass.bias.apply_hod

# Apply the NGC survey mask
python -m cmass.survey.ngc_selection

# Measure the power spectrum of the galaxy catalog
python -m cmass.summaries.Pk

Getting Started

See installation and usage instructions in INSTALL.md.

Organization

Below, we list the functionality of each script in the repository as well as its major dependencies:

cmass/conf

• This folder contains hydra configuration files for the pipeline.
• config.yaml - Construction of default configurations
• global.yaml - Global parameters (working directory, logging, etc.)
• nbody - Various gravity solver configs (resolution, timesteps, box size, etc.)
• bias - Biasing model configs (halo bias, HOD, etc.)
• fit - Fitting configs for bias models (fitting parameters, etc.)
• survey - Survey mask configs (geometry, fiber collisions, etc.)

cmass.nbody

• borglpt - Simulate a cubic volume using BORG 1/2LPT. Requires: borg.
• borgpm - Simulate a cubic volume using BORG PM. Requires: borg.
• pmwd - Simulate a cubic volume using PM-WD. Requires: pmwd.
• jax2lpt - Simulate a cubic volume using Jax2LPT. Requires: borg and jax_lpt. [DEPRECATED]

cmass.bias

• fit_halo_bias - Fit a halo biasing model to map density fields to halo counts. Requires: astropy and scipy.
• rho_to_halo - Sample halos from the density field using a pre-fit bias model. Requires: scipy and jax.
• apply_hod - Sample an HOD realization from the halo catalog using the Zheng+(2007) model. Requires: halotools.

cmass.survey

• remap_as_cuboid - Remap a periodic volume to a cuboid. Requires: cuboid_remap_jax.
• ngc_selection - Applies CMASS NGC survey mask to a lightcone-shaped volume of galaxies. Requires: pymangle, and astropy.

cmass.summaries

• Pk - Measure the power spectrum of a galaxy catalog. Requires: pypower.

Notebooks

• preprocess.ipynb - Executes various preprocessing tasks prepare for mass simulation. Designed to be run once at the start of code development. [Deprecated]
• validation.ipynb - Validates outputs at intermediate stages in the forward pipeline. [Deprecated]