Simulating the Galactic Multi-messenger Emissions with HERMES

TL;DR

HERMES is a versatile, publicly available simulation code that models multi-messenger emissions from the Galaxy, aiding in cosmic-ray studies, dark matter searches, and understanding diffuse astrophysical signals.

Contribution

The paper introduces HERMES, a modular and flexible Python-based code for simulating multi-messenger Galactic emissions across various wavelengths and particles, with detailed sky maps and spectra.

Findings

Generated comprehensive sky maps for radio, gamma-ray, and neutrino emissions.

Demonstrated the code's ability to model signals from dark matter annihilation.

Showcased the code's application in constraining cosmic-ray properties.

Abstract

The study of non-thermal processes such as synchrotron emission, inverse Compton scattering, bremsstrahlung and pion production is crucial to understand the properties of the Galactic cosmic-ray population, to shed light on their origin and confinement mechanisms, and to assess the significance of exotic signals possibly associated to new physics. We present a public code called HERMES aimed at generating sky maps associated to a variety of multi-messenger and multi-wavelength radiative processes, spanning from the radio domain all the way up to high-energy gamma-ray and neutrino production. We describe the physical processes under consideration, the code concept and structure, and the user interface, with particular focus on the python-based interactive mode. We especially present the modular and flexible design that allows to easily further extend the numerical package according to the user's needs. In order to demonstrate the capabilities of the code, we describe in detail a comprehensive set of sky maps and spectra associated to all physical processes included in the code. We comment in particular on the radio, gamma-ray, and neutrino maps, and mention the possibility to study signals stemming from dark matter annihilation. HERMES can be successfully applied to constrain the properties of the Galactic cosmic-ray population, improve our understanding of the diffuse Galactic radio, gamma--ray, and neutrino emission, and search for signals associated to particle dark matter annihilation or decay.