The locally observed cosmic ray spectrum has several puzzling features, such as the excess of positrons and antiprotons above ~20 GeV and the discrepancy in the slopes of the spectra of cosmic ray ...protons and heavier nuclei in the TeV-PeV energy range. We show that these features are consistently explained by a nearby source which was active approximately two million years ago and has injected (2-3)×10^{50} erg in cosmic rays. The transient nature of the source and its overall energy budget point to the supernova origin of this local cosmic ray source. The age of the supernova suggests that the local cosmic ray injection was produced by the same supernova that has deposited ^{60}Fe isotopes in the deep ocean crust.
Cosmic ray models Kachelrieß, M.; Semikoz, D.V.
Progress in particle and nuclear physics,
11/2019, Letnik:
109
Journal Article
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Odprti dostop
We review progress in high-energy cosmic ray physics focusing on recent experimental results and models developed for their interpretation. Emphasis is put on the propagation of charged cosmic rays, ...covering the whole range from ∼(20–50)GV, i.e. the rigidity when solar modulations can be neglected, up to the highest energies observed. We discuss models aiming to explain the anomalies in Galactic cosmic rays, the knee, and the transition from Galactic to extragalactic cosmic rays.
Detecting ALP wiggles at TeV energies Kachelrieß, M.; Tjemsland, J.
Journal of Cosmology and Astroparticle Physics,
01/2024, Letnik:
2024, Številka:
1
Journal Article
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.
Decays of mesons produced in cosmic ray induced air showers in Earth’s atmosphere can lead to a flux of light exotic particles which can be detected in underground experiments. We evaluate the energy ...spectra of the light neutral mesons π0, η, ρ0, ω, ϕ and J∕ψ produced in interactions of cosmic ray protons and helium nuclei with air using QCD inspired event generators. Summing up the mesons produced in the individual hadronic interactions of air showers, we obtain the resulting fluxes of undecayed mesons. As an application, we re-consider the case of millicharged particles created in the electromagnetic decay channels of neutral mesons.
Antideuteron and antihelium nuclei have been proposed as a detection channel for dark matter annihilations and decays in the Milky Way, due to the low astrophysical background expected. To estimate ...both the signal for various dark matter models and the astrophysical background, one usually employs the coalescence model in a Monte Carlo framework. This allows one to treat the production of antinuclei on an event-by-event basis, thereby taking into account momentum correlations between the antinucleons involved in the process. This approach lacks, however, an underlying microscopic picture, and the numerical value of the coalescence parameter obtained from fits to different reactions varies considerably. Here we propose instead to combine event-by-event Monte Carlo simulations with a microscopic coalescence picture based on the Wigner function representations of the produced antinuclei states. This approach allows us to include in a semi-classical picture both the size of the formation region, which is process dependent, and the momentum correlations. The model contains a single, universal parameter which is fixed by fitting the production spectra of antideuterons in proton–proton interactions, measured at the Large Hadron Collider. Using this value, the model describes well the production of various antinuclei both in electron–positron annihilation and in proton–proton collisions.
A signal of high-energy extraterrestrial neutrinos from unknown source(s) was recently discovered by the IceCube experiment. Neutrinos are always produced together with γ-rays, but the γ-ray flux ...from extragalactic sources is suppressed due to attenuation in the intergalactic medium. We report the discovery of a γ-ray excess at high galactic latitudes starting at energies 300 GeV in the data of the Fermi telescope. We show that the multi-TeV γ-ray diffuse emission has spectral characteristics at both low and high galactic latitudes compatible with those of the IceCube high neutrino signal in the same sky regions. This suggests that these γ-rays are the counterpart of the IceCube neutrino signal, implying that a sizable part of the IceCube neutrino flux originates from the Milky Way. We argue that the diffuse neutrino and γ-ray signal at high galactic latitudes originates either from previously unknown nearby cosmic ray “PeVatron” source(s), an extended galactic cosmic ray halo or from decays of heavy dark matter particles.
High-energy photons from blazars can initiate electromagnetic pair cascades interacting with the extragalactic photon background. The charged component of such cascades is deflected and delayed by ...extragalactic magnetic fields (EGMFs), thereby reducing the observed point-like flux and potentially leading to multi-degree images in the GeV energy range. We calculate the fluence of 1ES 0229+200 as seen by Fermi-LAT for different EGMF profiles using a Monte Carlo simulation for the cascade development. The non-observation of 1ES 0229+200 by Fermi-LAT suggests that the EGMF fills at least 60% of space with fields stronger than G for lifetimes of TeV activity of yr. Thus, the (non-)observation of GeV extensions around TeV blazars probes the EGMF in voids and puts strong constraints on the origin of EGMFs: either EGMFs were generated in a space filling manner (e.g., primordially) or EGMFs produced locally (e.g., by galaxies) have to be efficiently transported to fill a significant volume fraction as, e.g., by galactic outflows.
We aim to explain in a unified way the experimental data on ultrahigh-energy cosmic rays (UHECRs) and neutrinos, using a single source class and obeying limits on the extragalactic diffuse gamma-ray ...background. If UHECRs only interact hadronically with gas around their sources, the resulting diffuse cosmic-ray (CR) flux can be matched well to the observed one, providing at the same time large neutrino fluxes. Since the required fraction of heavy nuclei is, however, rather large, the maxima of air showers in the Earth’s atmosphere induced by UHECRs with energies E≳3×1018 eV would be too high. Therefore, additional photohadronic interactions of UHECRs close to the accelerator have to be present, in order to modify the nuclear composition of CRs in a relatively narrow energy interval. We thus include both photon and gas backgrounds and combine the resulting CR spectra with the high-energy part of the Galactic CR fluxes predicted by the escape model. As result, we find a good description of experimental data on the total CR flux, the mean shower maximum depth Xmax and its width rms(Xmax) in the whole energy range above E≃1017 eV. The predicted high-energy neutrino flux matches IceCube measurements, while the contribution to the extragalactic diffuse gamma ray background is of order 30%.
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