Colossus: A Python Toolkit for Cosmology, Large-Scale Structure, and Dark Matter Halos

Colossus1 is a recently available open-source, pure-python (nothing to compile) calculations toolkit developed by computational astrophysicist Benedikt Diemer during his PhD thesis work at University of Chicago.2

There are 3 separate python modules for cosmology, LSS, and DM Halos. You can choose to work with any of 20 built-in cosmology models based on results from Planck18 (with or w/o BAO), Planck15, Planck13, WMAP, etc. You can also create your own cosmology model by specifying values for a minimum of 6 parameters.

A paper on it is available at https://arxiv.org/abs/1712.04512. The code is available at this BitBucket repository. You can clone the repo, or download a zip file, or you can install it using pip. Documentation with many examples in html format is available here and the docs on the 3 modules are also available as interactive, live-code Jupyter notebooks here. The html tutorials doc files are just exports from the Jupyter notebooks.

Diemer has used it on at least two of his recent papers: An accurate physical model for halo concentrations [1809.07326] Modeling the atomic-to-molecular transition in cosmological simulations of galaxy formation [1806.02341]

Diemer expects future development work to continue on the code and invites bug reports, documentation feedback, feature requests, and collaborators (see the Future Development section at the end of the 1712.04512 paper).

An entry on it has been added to the Astrophysics Source Code Library. Regarding other tools, one site I saw that has a large software availability listing is Nasa's cosmology tools webpage. There's also a wikipedia page on cosmological computational software and the astrobites guide to astrophysical software. At a CosmoTools18 school event, 11 tools were covered and videos of the lectures are available here.

I installed Colossus on both an Ubuntu and a Windows 10 machine and it ran perfectly with no glitches. I typically use Spyder3 to create and run the code and JupyterLab for the notebooks. With numpy and matplotlib, it's easy to create plots.

There's also many good cosmology calculators online, e.g., ones at ICRAR, iCosmos, and Ned Wright's.

Reddit thread on this paper. ___

Footnotes: 1 Colossus is an acronym for COsmology, haLO, and large-Scale StrUcture toolS 2 Diemer's PhD thesis summary; On the (non-)universality of halo density profiles

Tags: #cosmology #software