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HERMES - High-Energy Radiative MESsengers

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About

gamma sky map from pi0

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.

Install

Quick procedure for those who know their way around:

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 use HERMES for your research, please cite

Dundovic et al., Astronomy and Astrophysics (2021); arXiv:2105.13165

Credits

Name Institution
Andrej Dundovic Gran Sasso Science Institute, L'Aquila, Italy
Carmelo Evoli Gran Sasso Science Institute, L'Aquila, Italy
Daniele Gaggero Instituto de Física Teórica UAM/CSIC, Madrid, Spain