hammurabi X: Simulating Galactic Synchrotron Emission with Random Magnetic Fields

Abstract

We present version X of the hammurabi package, the HEALPix-based numeric simulator for Galactic polarized emission. Improving on its earlier design, we have fully renewed the framework with modern C++ standards and features. Multi-threading support has been built in to meet the growing computational workload in future research. For the first time, we present precision profiles of hammurabi line-of-sight integral kernel with multi-layer HEALPix shells. In addition to fundamental improvements, this report focuses on simulating polarized synchrotron emission with Gaussian random magnetic fields. Two fast methods are proposed for realizing divergence-free random magnetic fields either on the Galactic scale where a field alignment and strength modulation are imposed, or on a local scale where more physically motivated models like a parameterized magneto-hydrodynamic (MHD) turbulence can be applied. As an example application, we discuss the phenomenological implications of Gaussian random magnetic fields for high Galactic latitude synchrotron foregrounds. In this, we numerically find B/E polarization mode ratios lower than unity based on Gaussian realizations of either MHD turbulent spectra or in spatially aligned magnetic fields.

arXiv comment25 pages, 18 figures, Accepted by ApJS with joint JOSS publication at https://doi.org/10.21105/joss.01889, the numerical package can be found at https://bitbucket.org/hammurabicode/hamx or https://github.com/hammurabi-dev/hammurabiX

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• Simulating the Galactic Multi-messenger Emissions with HERMES
• Absolute Calibration of Diffuse Radio Surveys at 45 and 150 MHz
• Spectral index of synchrotron emission: insights from the diffuse and magnetised interstellar medium
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• The effect of cosmic variance on the characteristics of dust polarization power spectra
• A new analytical model of the cosmic-ray energy flux for Galactic diffuse radio emission