Cosmic Ray Interstellar Propagation Tool using Itô Calculus (criptic): software for simultaneous calculation of cosmic ray transport and observational signatures

Abstract

We present criptic, the Cosmic Ray Interstellar Propagation Tool using Itô Calculus, a new open-source software package to simulate the propagation of cosmic rays through the interstellar medium and to calculate the resulting observable non-thermal emission. Criptic solves the Fokker-Planck equation describing transport of cosmic rays on scales larger than that on which their pitch angles become approximately isotropic, and couples this to a rich and accurate treatment of the microphysical processes by which cosmic rays in the energy range $\sim$MeV to $\sim$PeV lose energy and produce emission. Criptic is deliberately agnostic as to both the cosmic ray transport model and the state of the background plasma through which cosmic rays travel. It can solve problems where cosmic rays stream, diffuse, or perform arbitrary combinations of both, and the coefficients describing these transport processes can be arbitrary functions of the background plasma state, the properties of the cosmic rays themselves, and local integrals of the cosmic ray field itself (e.g., the local cosmic ray pressure or pressure gradient). The code is parallelised using a hybrid OpenMP-MPI paradigm, allowing rapid calculations exploiting multiple cores and nodes on modern supercomputers. Here we describe the numerical methods used in the code, our treatment of the microphysical processes, and the set of code tests and validations we have performed.

arXiv comment29 pages, 15 figures, accepted to MNRAS; very minor changes from first version. The software described is available from https://bitbucket.org/krumholz/criptic/src/master/, and a users' guide can be found at https://criptic.readthedocs.io/

References in corpus (49)

• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• The chemical composition of the Sun
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Cosmic-ray propagation and interactions in the Galaxy
• Propagation of cosmic-ray nucleons in the Galaxy
• Energy spectra of gamma-rays, electrons and neutrinos produced at proton-proton interactions in the very high energy regime
• Parametrization of gamma-ray production cross-sections for pp interactions in a broad proton energy range from the kinematic threshold to PeV energies
• The 511 keV emission from positron annihilation in the Galaxy
• Science with the Cherenkov Telescope Array
• Galactic winds driven by cosmic-ray streaming
• Dense gas in the Galactic central molecular zone is warm and heated by turbulence
• The Physics of the FIR-Radio Correlation: I. Calorimetry, Conspiracy, and Implications
• Magnetic Fields in Starburst Galaxies and The Origin of the FIR-Radio Correlation
• Cosmic-ray Driven Outflows in Global Galaxy Disk Models
• Launching cosmic-ray-driven outflows from the magnetized interstellar medium
• Cosmic-ray propagation with DRAGON2: I. numerical solver and astrophysical ingredients
• But What About... Cosmic Rays, Magnetic Fields, Conduction, & Viscosity in Galaxy Formation
• A cosmic-ray dominated ISM in Ultra Luminous Infrared Galaxies: new initial conditions for star formation
• Cosmic ray feedback in the FIRE simulations: constraining cosmic ray propagation with GeV gamma ray emission
• Effective destruction of CO by cosmic rays: implications for tracing H${}_2$ gas in the Universe
• The Eddington Limit in Cosmic Rays: An Explanation for the Observed Faintness of Starbursting Galaxies
• PICARD: A novel code for the Galactic Cosmic Ray propagation problem
• Cosmic ray physics in calculations of cosmological structure formation
• Cosmic ray-driven galactic winds: streaming or diffusion?
• The Physics of the FIR-Radio Correlation: II. Synchrotron Emission as a Star-Formation Tracer in High-Redshift Galaxies
• On photohadronic processes in astrophysical environments
• Cosmic ray transport in starburst galaxies
• Cosmic ray transport and radiative processes in nuclei of starburst galaxies
• The Central 300 pc of the Galaxy probed by infrared spectra of H${}_3^{+}$ and CO: part I. Predominance of warm and diffuse gas and high H${}_2$ ionization rate
• Active Galactic Nuclei, Neutrinos, and Interacting Cosmic Rays in NGC 253 & NGC 1068
• Effects of Different Cosmic Ray Transport Models on Galaxy Formation
• A physical model for the [CII]-FIR deficit in luminous galaxies
• Powderday: Dust Radiative Transfer for Galaxy Simulations
• The diffuse $\gamma$-ray background is dominated by star-forming galaxies
• Cosmic rays and non-thermal emission in simulated galaxies: III. probing cosmic ray calorimetry with radio spectra and the FIR-radio correlation
• First Predicted Cosmic Ray Spectra, Primary-to-Secondary Ratios, and Ionization Rates from MHD Galaxy Formation Simulations
• Equipartition and Cosmic Ray Energy Densities in Central Molecular Zones of Starbursts
• Cosmic rays and non-thermal emission in simulated galaxies. II. $\gamma$-ray maps, spectra and the far infrared-$\gamma$-ray relation
• CRPropa 3.1 -- A low energy extension based on stochastic differential equations
• Cosmic-Ray Transport in Varying Galactic Environments
• Cosmic rays across the star-forming galaxy sequence. I: Cosmic ray pressures and calorimetry
• The global structure of magnetic fields and gas in simulated Milky Way-analogue galaxies
• On the shape of the gamma-ray spectrum around the "${\pi }^0$-bump"
• Cosmic rays across the star-forming galaxy sequence. II: Stability limits and the onset of cosmic ray-driven outflows
• Rigorous theory for secondary cosmic-ray ionization
• Observable Signatures of Cosmic Rays Transport in Starburst Galaxies on Gamma-ray and Neutrino Observations
• Parametrization of the nucleus-nucleus gamma-ray production cross sections below 100 GeV/nucleon: Subthreshold pions and Hard photons
• Atomic Carbon in the Central Molecular Zone of the Milky Way : Possible Cosmic-ray Induced Chemistry or Time-Dependent Chemistry Associated with SNR Sagittarius A East

Cited by in corpus (6)

• Turbulent diffusion of streaming cosmic rays in compressible, partially ionised plasma
• Where are Milky Way's Hadronic PeVatrons?
• The cosmic ray ionisation and $\gamma$-ray budgets of star-forming galaxies
• The fragmentation of molecular clouds in starburst environments
• Gauging the Impact of Cosmic Ray Feedback on the Stellar Initial Mass Function
• Updated Constraints on the Injection Energy of Positrons Generating the Galactic 511 keV $\gamma$-ray line