FLAReS

FLAReS (Full-sky Lensing with Adaptive Resolution Shells) provides a python package for full-sky weak lensing simulations with non-Gaussianity analysis.

Characteristics

• Construct spherical lens shell from Nbody boxes.
• Efficient Nboy box arrangement for lens shells in differnt redshift.
• Measure non-Gaussianity parameters (Skewness & Kurtosis) of lensing maps either locally or globally.

Installation

To install FLAReS, navigate to the directory where you downloaded the package and install it using pip:

cd FLAReS
pip install .

Example

• A quarter cross-section view (to scale) of one of the example lens shell arrangements for CMB lensing simulation. The shells are distinguished by different colors, and the grid represents the scaled N-body box

  

• N-body box stacking strategies for constructing one of the lensing shells.

  

FLAReS Workflow

This section provides a step-by-step guide for generating, running, and processing N-body simulations, shell construction, and lensing calculations using FLAReS.

1. Generate Parameter File

The parameter file parameter.ini contains all the required simulation and analysis parameters. Ensure this file is prepared before proceeding to the next steps. Examples for the parameter file are provided in the FLAReS/param folder.

2. Generate Shell Arrangement and Gadget-4 Configuration

Run the following command to generate the necessary files, including shell arrangement and N-body configuration files for Gadget-4:

python gen_Nbody_run.py -p parameter.ini

Output

• Shell arrangement files for your simulation.
• N-body configuration files required to run Gadget-4.

3. Run Gadget-4 Simulations

Directory for Configuration Files

The generated N-body configuration files and related data will be stored in: /FLAReS/projects/<project-name>/<Nbody_folder-name>

Example PBS Scripts for Cluster

If running on a PBS cluster, example job scripts are available at: /FLAReS/projects/<project-name>/cluster

Submit the PBS job to the cluster system:

qsub example_script.pbs

4. Constructing the Shell

To construct the lensing shell, run:

python shell_run.py -p parameter.ini

Output

• Lensing shell maps will be generated in the following directory: /FLAReS/projects/<project-name>/shells

5. Correcting Shell Thickness

Generate shell thickness corrections to account for the effects of finite shell thickness:

python shell_thickness_correction.py -p parameter.ini

Output

The correction data will be stored in spherical harmonic space within the corresponding shell directory.

6. Lensing Process

Perform lensing calculations with either post-Born corrections or the Born approximation.

Lensing with Post-Born Corrections

python lensing_post-Born_run.py -p parameter.ini

Lensing with Born Approximation

python lensing_post-Born_run.py -p parameter.ini

Citing

If you use FLAReS in your research, please cite it as follows:

@article{Hamann:2024ywo,
    author = "Hamann, Jan and Kang, Yuqi",
    title = "{Non-Gaussianity in CMB lensing from full-sky simulations}",
    eprint = "2411.02774",
    archivePrefix = "arXiv",
    primaryClass = "astro-ph.CO",
    month = "11",
    year = "2024"
}

Developer

Yuqi Kang