GALPROP Code for Galactic Cosmic Ray Propagation and Associated Photon Emissions

Abstract

Recent years are marked with many breakthroughs in astrophysics of cosmic rays (CRs), and more are expected in the nearest future. Their proper interpretation is impossible without a welldeveloped propagation code. The GALPROP project celebrates its 19th anniversary this year. Over these years the project has established itself as a standard self-consistent model for CR propagation in the Galaxy and associated diffuse emissions (radio, microwave, X-rays, γ-rays) that is widely used by the astrophysical community. The project stimulated independent studies of the interstellar radiation field, distribution of the interstellar gas (H2, H I, H II), synchrotron emission and the Galactic magnetic field, and a new study of the isotopic production cross sections. These studies provide necessary and unique input datasets for the GALPROP model. The code is optimized and parallelized and accessible as a standalone executable or library that can be linked to other codes enabling many other studies, such as Markov Chain Monte Carlo (MCMC), MultiNest, SuperBayeS, and DarkSUSY. We describe a new updated version of the code that has new capabilities and improved accuracy. As always, the latest release of the code is available through the WebRun, a service to the scientific community enabling easy use of the GALPROP code via web browsers.

The Nine Lives of Cosmic Rays in Galaxies

“…The study of CR secondaries, so important for propagation studies, is still limited by the accuracy of nuclear cross-sections. An initiative to improve them is described by Moskalenko (2011). A new treatment of the complicated processes involving the light (Z≤ 2) nuclei is given in Coste et al (2012), including for example Deuterium production by p-p fusion reactions.…”

Power requirements for cosmic ray propagation models involving re-acceleration and a comment on second-order Fermi acceleration theory

“…The importance of re-acceleration for cosmic ray transport in the Galaxy has been debated inconclusively for many years (Simon, Heinrich, & Mathis 1986;Cesarsky 1988;Seo & Ptuskin 1994;Shalchi & Büsching 2010;Trotta et al 2011, among many others) but is widely thought to be important and is routinely implemented, for example, in the de facto standard numerical model GALPROP (Moskalenko & GALPROP Team 2013). At some level it is clear that re-acceleration, which is just the second-order Fermi acceleration associated with the same interstellar turbulence that produces the spatial diffusion, must occur.…”

Exploring the MeV sky with a combined coded mask and Compton telescope: the Galactic Explorer with a Coded aperture mask Compton telescope (GECCO)

“…Their detection allows study of the spectra, composition, and distribution of CR nuclei below the kinetic energy threshold for production of neutral pions (∼300 MeV for p+p collisions). The most intense lines are expected to be from the deexcitation of the first nuclear levels in 12 C, 16 O, 20 Ne, 24 Mg, 28 Si, and 56 Fe [34]. The total nuclear line emission is also composed of broad lines produced by interaction of CR heavy ions with the H and He nuclei of the interstellar gas, and of thousands of weaker lines [9].…”