The Python Sky Model: software for simulating the Galactic microwave sky

2016/08/09 by Ben Thorne, B. Thorne, Jo Dunkley +6 · 251 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Cosmic microwave background #Cosmology and Gravitation Theories #Microwave #Operating system #Optics #Physics #Python (programming language) #Radio Astronomy Observations and Technology #Sky #Software #astro-ph.CO

paper · pdf · doi:10.1093/mnras/stx949

published in Monthly Notices of the Royal Astronomical Society 469(3), 2821-2833 (Oxford University Press) · 12 pages, 11 figures

arxiv created 2016/08/09 · openalex publication_date 2017/04/20 · arxiv updated 2017/06/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We present a numerical code to simulate maps of Galactic emission in intensity and polarization at microwave frequencies, aiding in the design of cosmic microwave background experiments. This python code builds on existing efforts to simulate the sky by providing an easy-to-use interface and is based on publicly available data from the WMAP (Wilkinson Microwave Anisotropy Probe) and Planck satellite missions. We simulate synchrotron, thermal dust, free–free and anomalous microwave emission over the whole sky, in addition to the cosmic microwave background, and include a set of alternative prescriptions for the frequency dependence of each component, for example, polarized dust with multiple temperatures and a decorrelation of the signals with frequency, which introduce complexity that is consistent with current data. We also present a new prescription for adding small-scale realizations of these components at resolutions greater than current all-sky measurements. The usefulness of the code is demonstrated by forecasting the impact of varying foreground complexity on the recovered tensor-to-scalar ratio for the LiteBIRD satellite. The code is available at: https://github.com/bthorne93/PySM_public.

Citations

• Three‐YearWilkinson Microwave Anisotropy Probe(WMAP) Observations: Temperature Analysis

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