COLOSSUS: A python toolkit for cosmology, large-scale structure, and dark matter halos

TL;DR

Colossus is an open-source Python toolkit that provides fast, accurate calculations for cosmology, large-scale structure, and dark matter halo properties, facilitating research in these areas.

Contribution

It introduces a comprehensive, user-friendly Python package with extensive modules and fitting functions for cosmology and structure formation calculations.

Findings

Efficient implementation of cosmological calculations

Inclusion of over 40 fitting functions from literature

Validated accuracy of core routines

Abstract

This paper introduces Colossus, a public, open-source python package for calculations related to cosmology, the large-scale structure (LSS) of matter in the universe, and the properties of dark matter halos. The code is designed to be fast and easy to use, with a coherent, well-documented user interface. The cosmology module implements Friedman-Lemaitre-Robertson-Walker cosmologies including curvature, relativistic species, and different dark energy equations of state, and provides fast computations of the linear matter power spectrum, variance, and correlation function. The LSS module is concerned with the properties of peaks in Gaussian random fields and halos in a statistical sense, including their peak height, peak curvature, halo bias, and mass function. The halo module deals with spherical overdensity radii and masses, density profiles, concentration, and the splashback radius. To facilitate the rapid exploration of these quantities, Colossus implements more than 40 different fitting functions from the literature. I discuss the core routines in detail, with particular emphasis on their accuracy. Colossus is available at bitbucket.org/bdiemer/colossus.