High-energy γ-rays of interstellar origin are produced by the interaction of cosmic-ray (CR) particles with the diffuse gas and radiation fields in the Galaxy. The main features of this emission are ...well understood and are reproduced by existing CR propagation models employing 2D galactocentric cylindrically symmetrical geometry. However, the high-quality data from instruments like the Fermi Large Area Telescope reveal significant deviations from the model predictions on few to tens of degrees scales, indicating the need to include the details of the Galactic spiral structure and thus requiring 3D spatial modeling. In this paper, the high-energy interstellar emissions from the Galaxy are calculated using the new release of the GALPROP code employing 3D spatial models for the CR source and interstellar radiation field (ISRF) densities. Three models for the spatial distribution of CR sources are used that are differentiated by their relative proportion of input luminosity attributed to the smooth disk or spiral arms. Two ISRF models are developed based on stellar and dust spatial density distributions taken from the literature that reproduce local near- to far-infrared observations. The interstellar emission models that include arms and bulges for the CR source and ISRF densities provide plausible physical interpretations for features found in the residual maps from high-energy γ-ray data analysis. The 3D models for CR and ISRF densities provide a more realistic basis that can be used for the interpretation of the nonthermal interstellar emissions from the Galaxy.
We provide a compilation of predictions of the QGSJET-II-04m model for the production of secondary species (photons, neutrinos, electrons, positrons, and antinucleons) that are covering a wide range ...of energies of the beam particles in proton–proton, proton–nucleus, nucleus–proton,and nucleus–nucleus reactions. The current version of QGSJET-II-04m has an improved treatment of the production of secondary particles at low energies: the parameters of the hadronization procedure have been fine-tuned, based on a number of recent benchmark experimental data, notably, from the LHCf, LHCb, and NA61 experiments. Our results for the production spectra are made publicly accessible through the interpolation routines AAfrag which are described below. Besides, we comment on the impact of Feynman scaling violation and isospin symmetry effects on antinucleon production.
Program Title:AAfrag 1.01
Program Files doi:http://dx.doi.org/10.17632/6f73jz6jx8.1
Licensing provisions: CC by NC 3.0.
Programming language: Fortran 90
Supplementary material: see http://aafrag.sourceforge.io
Nature of problem: Calculation of secondaries (photons, neutrinos, electrons, positrons, protons, and antiprotons) produced in hadronic interactions
Solution method: Results from the Monte Carlo simulation QGSJET-II-04m are interpolated.
ABSTRACT Since 2012 August Voyager 1 has been observing the local interstellar energy spectra of Galactic cosmic-ray nuclei down to 3 MeV nuc−1 and electrons down to 2.7 MeV. The H and He spectra ...have the same energy dependence between 3 and 346 MeV nuc−1, with a broad maximum in the 10-50 MeV nuc−1 range and a H/He ratio of 12.2 0.9. The peak H intensity is ∼15 times that observed at 1 AU, and the observed local interstellar gradient of 3-346 MeV H is −0.009 0.055% AU−1, consistent with models having no local interstellar gradient. The energy spectrum of electrons (e− + e+) with 2.7-74 MeV is consistent with E−1.30 0.05 and exceeds the H intensity at energies below ∼50 MeV. Propagation model fits to the observed spectra indicate that the energy density of cosmic-ray nuclei with >3 MeV nuc−1 and electrons with >3 MeV is 0.83-1.02 eV cm−3 and the ionization rate of atomic H is in the range of 1.51-1.64 × 10−17 s−1. This rate is a factor >10 lower than the ionization rate in diffuse interstellar clouds, suggesting significant spatial inhomogeneity in low-energy cosmic rays or the presence of a suprathermal tail on the energy spectrum at much lower energies. The propagation model fits also provide improved estimates of the elemental abundances in the source of Galactic cosmic rays.
Abstract
The past decade has brought impressive advances in the astrophysics of cosmic rays (CRs) and multiwavelength astronomy, thanks to the new instrumentation launched into space and built on the ...ground. Modern technologies employed by those instruments provide measurements with unmatched precision, enabling searches for subtle signatures of dark matter and new physics. Understanding the astrophysical backgrounds to better precision than the observed data is vital in moving to this new territory. A state-of-the-art CR propagation code, called
GalProp,
is designed to address exactly this challenge. Having 25 yr of development behind it, the
GalProp
framework has become a de facto standard in the astrophysics of CRs, diffuse photon emissions (radio to
γ
-rays), and searches for new physics.
GalProp
uses information from astronomy, particle physics, and nuclear physics to predict CRs and their associated emissions self-consistently, providing a unifying modeling framework. The range of its physical validity covers 18 orders of magnitude in energy, from sub-keV to PeV energies for particles and from
μ
eV to PeV energies for photons. The framework and the data sets are public and are extensively used by many experimental collaborations and by thousands of individual researchers worldwide for interpretation of their data and for making predictions. This paper details the latest release of the
GalProp
framework and updated cross sections, further developments of its initially auxiliary data sets for models of the interstellar medium that grew into independent studies of the Galactic structure—distributions of gas, dust, radiation, and magnetic fields—as well as the extension of its modeling capabilities. Example applications included with the distribution illustrating usage of the new features are also described.
Local interstellar spectra (LIS) for protons, helium, and antiprotons are built using the most recent experimental results combined with state-of-the-art models for propagation in the Galaxy and ...heliosphere. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of cosmic-ray (CR) species at different modulation levels and at both polarities of the solar magnetic field. To do so in a self-consistent way, an iterative procedure was developed, where the GALPROP LIS output is fed into HelMod, providing modulated spectra for specific time periods of selected experiments to compare with the data; the HelMod parameter optimization is performed at this stage and looped back to adjust the LIS using the new GALPROP run. The parameters were tuned with the maximum likelihood procedure using an extensive data set of proton spectra from 1997 to 2015. The proposed LIS accommodate both the low-energy interstellar CR spectra measured by Voyager 1 and the high-energy observations by BESS, Pamela, AMS-01, and AMS-02 made from the balloons and near-Earth payloads; it also accounts for Ulysses counting rate features measured out of the ecliptic plane. The found solution is in a good agreement with proton, helium, and antiproton data by AMS-02, BESS, and PAMELA in the whole energy range.
The Goos-Hänchen effect and Fano resonance are studied in photonic crystals that are considered Fourier counterparts in wave-vector-coordinate space. The Goos-Hänchen effect, which is enhanced by the ...excitation of Bloch surface electromagnetic waves, is visualized using far-field microscopy and measured at the surface of photonic crystals by angular spectroscopy. The maximal Goos-Hänchen shift is observed to be 66 μm.
ABSTRACT We present the results of the most complete scan of the parameter space for cosmic ray (CR) injection and propagation. We perform a Bayesian search of the main GALPROP parameters, using the ...MultiNest nested sampling algorithm, augmented by the BAMBI neural network machine-learning package. This is the first study to separate out low-mass isotopes (p, , and He) from the usual light elements (Be, B, C, N, and O). We find that the propagation parameters that best-fit , and He data are significantly different from those that fit light elements, including the B/C and 10Be/9Be secondary-to-primary ratios normally used to calibrate propagation parameters. This suggests that each set of species is probing a very different interstellar medium, and that the standard approach of calibrating propagation parameters using B/C can lead to incorrect results. We present posterior distributions and best-fit parameters for propagation of both sets of nuclei, as well as for the injection abundances of elements from H to Si. The input GALDEF files with these new parameters will be included in an upcoming public GALPROP update.
The next generation magnetic spectrometer in space, AMS-100, is designed to have a geometrical acceptance of 100 m 2 sr and to be operated for at least ten years at the Sun–Earth Lagrange Point 2. ...Compared to existing experiments, it will improve the sensitivity for the observation of new phenomena in cosmic rays, and in particular in cosmic antimatter, by at least a factor of 1000. The magnet design is based on high temperature superconductor tapes, which allow the construction of a thin solenoid with a homogeneous magnetic field of 1 Tesla inside. The inner volume is instrumented with a silicon tracker reaching a maximum detectable rigidity of 100 TV and a calorimeter system that is 70 radiation lengths deep, equivalent to four nuclear interaction lengths, which extends the energy reach for cosmic-ray nuclei up to the PeV scale, i.e. beyond the cosmic-ray knee. Covering most of the sky continuously, AMS-100 will detect high-energy gamma-rays in the calorimeter system and by pair conversion in the thin solenoid, reconstructed with excellent angular resolution in the silicon tracker.
Local interstellar spectra (LIS) of secondary cosmic-ray (CR) nuclei, lithium, beryllium, boron, and partially secondary nitrogen, are derived in the rigidity range from 10 MV to ∼200 TV using the ...most recent experimental results combined with state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. The lithium spectrum appears somewhat flatter at high energies compared to other secondary species, which may imply a primary lithium component. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. An iterative maximum-likelihood method is developed that uses GALPROP-predicted LIS as input to HelMod, which provides the modulated spectra for specific time periods of the selected experiments for the model-data comparison. The proposed LIS accommodates the low-energy interstellar spectra measured by Voyager 1, the High Energy Astrophysics Observatory-3 (HEAO-3), and the Cosmic Ray Isotope Spectrometer on board of the Advanced Composition Explorer (ACE/CRIS), as well as the high-energy observations by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), Alpha Magnetic Spectrometer-02 (AMS-02), and earlier experiments that are made deep in the heliosphere. The interstellar and heliospheric propagation parameters derived in this study are consistent with our earlier results for propagation of CR protons, helium, carbon, oxygen, antiprotons, and electrons.
We use the GALPROP code for cosmic-ray (CR) propagation to calculate the broadband luminosity spectrum of the Milky Way related to CR propagation and interactions in the interstellar medium. This ...includes {gamma}-ray emission from the production and subsequent decay of neutral pions ({pi}{sup 0}), bremsstrahlung, and inverse Compton scattering, and synchrotron radiation. The Galaxy is found to be nearly a CR electron calorimeter, but only if {gamma}-ray emitting processes are taken into account. Synchrotron radiation alone accounts for only one-third of the total electron energy losses with {approx}10%-20% of the total synchrotron emission from secondary CR electrons and positrons. The relationship between far-infrared and radio luminosity that we find from our models is consistent with that found for galaxies in general. The results will be useful for understanding the connection between diffuse emissions from radio through {gamma}-rays in 'normal' (non-active galactic nucleus dominated) galaxies as well as for estimating the broadband extragalactic diffuse background from these kinds of galaxies.
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