HERMES - High-Energy Radiative MESsengers

About

HERMES is a publicly available computational framework for the line of sight integration which creates sky maps in the HEALPix-compatibile format of various galactic radiative processes including Faraday rotation, synchrotron and free-free radio emission, gamma-ray emission from pion-decay, bremsstrahlung and inverse-Compton. The name is an acronym for "High-Energy Radiative MESsengers".

The code is written in C++ relying on features of the language's recent revisions (C++11, C++14). Once compiled, HERMES can optionally be used from Python thanks to pybind11 (Python 2.X is not supported). Some components of the code (such as galactic magnetic field models, vector and grid classes) were adopted from CRPropa 3, a code for cosmic ray propagation.

HERMES provides the following integrators:

• Dispersion measure
• Rotation measure
• Free-Free emission
• Synchrotron emission (with absorption)
• Pion decay gamma-ray emission
• Inverse Compton scattering
• Bremsstrahlung
• Gamma-ray emissions from Dark Matter annihilation

The complete feature list is documented on github.io.

Quickstart

If Docker or Podman is installed, one can quickly enter a Jupyter notebook with HERMES already built and available:

docker run -it --rm -p 8888:8888 quay.io/cosmicrays/jupyter-hermes:latest

The notebook can be accessed via web browser following the link in the output of the above command.

For more details how to use containers see INSTALL - Use with Docker/Podman image and Jupyter Docker Stacks.

Install

For those who know their way around, the make-install procedure is available:

mkdir build
cd build
cmake ..
make -j

For detailed installation guides and requirements see INSTALL.

Usage

from pyhermes import *
from pyhermes.units import TeV, deg, kpc, pc

nside = 512
Egamma = 0.1*TeV
obs_pos = Vector3QLength(8.0*kpc, 0*pc, 0*pc)

skymap = GammaSkymap(nside, Egamma)
mask = RectangularWindow([5*deg, 40*deg], [-5*deg, 90*deg])
skymap.setMask(mask)

neutral_gas = neutralgas.RingModel(neutralgas.GasType.HI)
cosmicray_protons = cosmicrays.Dragon2D(Proton)
pp_crosssection = interactions.Kamae06Gamma()

integrator = PiZeroIntegrator(cosmicray_protons, neutral_gas, pp_crosssection)
integrator.setObsPosition(obs_pos)
integrator.setupCacheTable(100, 100, 20)

skymap.setIntegrator(integrator)
skymap.compute()

output = outputs.HEALPixFormat("!pizero-dragon2d.fits.gz")
skymap.save(output)

More examples can be found in the examples repository. Full documentation of the code is available here.

How to cite HERMES

If you have used HERMES in a scientific project that lead to a publication, we'd appreciate you citing the paper associated with it:

@ARTICLE{HermesCode,
       author = {{Dundovic}, A. and {Evoli}, C. and {Gaggero}, D. and {Grasso}, D.},
        title = "{Simulating the Galactic multi-messenger emissions with HERMES}",
      journal = {\aap},
         year = 2021,
        month = sep,
       volume = {653},
          eid = {A18},
        pages = {A18},
          doi = {10.1051/0004-6361/202140801},
          url = {https://doi.org/10.1051/0004-6361/202140801},
archivePrefix = {arXiv},
       eprint = {2105.13165},
 primaryClass = {astro-ph.HE},
}

Credits