UFalcon

With upcoming surveys set to drastically increase the both the amount of large-scale structure (LSS) data and cosmic microwave background (CMB) data it is increasingly important to create correlated map-level simulations of different cosmological probes. This enables several applications that are relevant to current cosmological research:

• Covariance matrix estimation 
• Map-level analysis 
• Testing impacts of systematics and foreground cleaning
  

For this reason we created UFalcon (Ultra Fast Lightcone): a tool for rapidly post-processing N-body code output into signal maps for many different cosmological probes. This code was originally configured to output weak lensing convergence maps from N-body lightcones and first introduced in (external pageSgier et al. 2019call_made, external pageSgier et al. 2020call_made) and extended in (external pageReeves et al. 2023call_made). The most recent version, UFalconv2, is able to produce maps of weak-lensing convergence, linear-bias galaxy overdenisty, cosmic micowave background (CMB) lensing convergence and the integrated Sachs-Wolfe temperature perturbation given a set of N-body lightcones. The output of the code for the above signals has been tested against analytical theoretical predictions to a high degree of accuracy in Reeves et al. 2023 (external pagehttps://arxiv.org/abs/2309.03258call_made). The package offers a high flexibility for the lightcone construction, such as user-specific survey- redshift ranges, redshift distributions and single-source redshifts.

The pipeline is primarily designed to post-​process output of the dark-​matter only N-​Body simulation code PKDGRAV3 (external pagePotter et al. 2016call_made), but is in general able to use output of different N-​Body codes (e.g. the approximate N-​Body codes L-​PICOLA (external pageHowlett et al. 2015call_made) and Pinocchio (external pageMonaco et al. 2002call_made). In particular, the code can be interfaced with the cosmogrid (external pageKacprzak et el. 2022call_made) available here (external pagecosmogrid websitecall_made) a large suite of PKDGRAV3 simulations at 2500 different cosmologies stored as lightcone output.

Code Release and Documentation

The latest public release is available on .

Publications  

A first implementation of the UFalcon pipeline is presented in external pageSgier et al. 2019call_made, external pageSgier et al. 2020call_made and extended in external pageReeves et al. 2023call_made.

In external pageReeves et. al 2023call_made, the codebase underwent a major update to enable the post-procesing over several different cosmological probes from N-body code lightcones. The implementation is described in the paper along with several validation tests.  

Usage

The usage section in the software documentation contains an example notebook which describes how to produce maps of weak lensing convergence, galaxy clustering, CMB lensing convergence and the ISW temperature perturbation given an input N-body code lightcone.