Journal articles: 'Cosmic-ray theory'

1

Hand, Eric. "Cosmic-ray theory unravels." Nature 463, no. 7284 (2010): 1011. http://dx.doi.org/10.1038/4631011a.

APA, Harvard, Vancouver, ISO, and other styles

2

Ferreira, Stefan E. S. "Theory of cosmic ray modulation." Proceedings of the International Astronomical Union 4, S257 (2008): 429–38. http://dx.doi.org/10.1017/s1743921309029664.

Full text

Abstract:

AbstractThis work aims to give a brief overview on the topic of cosmic ray modulation in the heliosphere. The heliosphere, heliospheric magnetic field, transport parameters and the transport equation together with modulation models, which solve this equation in various degree of complexity, are briefly discussed. Results from these models are then presented where first it is shown how cosmic rays are globally distributed in an asymmetrical heliosphere which results from the relative motion between the local interstellar medium and the Sun. Next the focus shifts to low-energy Jovian electrons. The intensities of these electrons, which originate from a point source in the inner heliosphere, exhibit a unique three-dimensional spiral structure where most of the particles are transported along the magnetic field lines. Time-dependent modulation is also discussed where it is shown how drift effects together with propagating diffusion barriers are responsible for modulation over a solar cycle.

APA, Harvard, Vancouver, ISO, and other styles

3

Dorman, L. I., and I. V. Dorman. "Cosmic-ray atmospheric electric field effects." Canadian Journal of Physics 73, no. 7-8 (1995): 440–43. http://dx.doi.org/10.1139/p95-063.

Full text

Abstract:

Experimental data on the atmospheric electric field effect in the cosmic-ray muon component are discussed on the basis of the general theory of cosmic-ray meteorological effects. In this framework, we develop the theory of atmospheric electric field effects in the hard- and soft-muons of secondary cosmic rays and in the neutron-monitor counting rates as well. We show that the experimental results can be understood on the basis of this theory. We also show that a sufficient atmospheric electric field effect in the cosmic-ray neutron component is to be expected because the neutron monitors work as analyzers of soft muons and really detect only negative muons as well as neutrons.

APA, Harvard, Vancouver, ISO, and other styles

4

Ivlev, Alexei V., Kedron Silsbee, Marco Padovani, and Daniele Galli. "Rigorous Theory for Secondary Cosmic-Ray Ionization." Astrophysical Journal 909, no. 2 (2021): 107. http://dx.doi.org/10.3847/1538-4357/abdc27.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Starodubtsev, Sergei. "Shape of spectrum of galactic cosmic ray intensity fluctuations." Solar-Terrestrial Physics 8, no. 2 (2022): 71–75. http://dx.doi.org/10.12737/stp-82202211.

Full text

Abstract:

The impact of solar wind plasma on fluxes of galactic cosmic rays (CR) penetrating from the outside into the heliosphere with energies above ~1 GeV leads to temporal variations in the CR intensity in a wide frequency range. Cosmic rays being charged particles, their modulation occurs mainly under impacts of the interplanetary magnetic field. It is well known that the observed spectrum of interplanetary magnetic field (IMF) fluctuations in a wide frequency range ν from ~10–7 to ~10 Hz has a pronounced falling character and consists of three sections: energy, inertial, and dissipative. Each of them is described by the power law PIMF(ν)~ν–α, while the IMF spectrum index α increases with increasing frequency. The IMF fluctuations in each of these sections are also characterized by properties that depend on their nature. Also known are established links between fluctuation spectra of the interplanetary magnetic field and galactic cosmic rays in the case of modulation of the latter by Alfvén or fast magnetosonic waves. The theory predicts that fluctuation spectra of cosmic rays should also be described by the power law PCR(ν)~ν–γ. However, the results of many years of SHICRA SB RAS research into the nature and properties of cosmic ray intensity fluctuations based on data from neutron monitors at stations with different geomagnetic cut-offs RC from 0.5 to 6.3 GV show that the observed spectrum of fluctuations in galactic cosmic ray intensity in the frequency range above 10–4 Hz becomes flat, i.e. it is similar to white noise. This fact needs to be realized and explained. This paper reports the results of research into the shape of the spectrum of galactic cosmic ray intensity fluctuations within a frequency range ν from ~10–6 to ~1 Hz and compares them with model calculations of white noise spectra, using measurement data from the neutron monitor of the Apatity station. A possible physical explanation has been given for the observed shape of the cosmic ray fluctuation spectrum on the basis of the known mechanisms of their modulation in the heliosphere.

APA, Harvard, Vancouver, ISO, and other styles

6

Wentzel, Donat G. "Self-Confined Cosmic Rays." Symposium - International Astronomical Union 107 (1985): 341–54. http://dx.doi.org/10.1017/s007418090007580x.

Full text

Abstract:

Cosmic rays do not stream freely through the galaxy, contrary to earlier expectations. Streaming cosmic rays are slowed down by the emission of resonant Alfven waves that scatter the cosmic rays. The theory of self-confinement explains the isotropy of the bulk of the cosmic rays but not of cosmic rays above 103 Gev; it has been a stimulus to the theory for cosmic-ray acceleration at supernova shocks; and, on inclusion of diffusion in a galactic wind, it may explain the uniform cosmic-ray density out to 18 kpc in our galaxy. Rapidly streaming electrons in clusters of galaxies, in supernova remnants, and near solar flares are accomodated by the theory when it is expanded to include the effects of hot plasmas and other wave modes. A “resonance gap” may prevent the turning backwards of streaming particles and thus allow streaming near the particle speed.

APA, Harvard, Vancouver, ISO, and other styles

7

Shalchi, A. "Second-order quasilinear theory of cosmic ray transport." Physics of Plasmas 12, no. 5 (2005): 052905. http://dx.doi.org/10.1063/1.1895805.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

KUSENKO, ALEXANDER. "COSMIC CONNECTIONS: FROM COSMIC RAYS TO GAMMA RAYS, COSMIC BACKGROUNDS AND MAGNETIC FIELDS." Modern Physics Letters A 28, no. 02 (2013): 1340001. http://dx.doi.org/10.1142/s0217732313400014.

Full text

Abstract:

Combined data from gamma-ray telescopes and cosmic-ray detectors have produced some new surprising insights regarding intergalactic and galactic magnetic fields, as well as extragalactic background light. We review some recent advances, including a theory explaining the hard spectra of distant blazars and the measurements of intergalactic magnetic fields based on the spectra of distant sources. Furthermore, we discuss the possible contribution of transient galactic sources, such as past gamma-ray bursts and hypernova explosions in the Milky Way, to the observed flux of ultrahigh-energy cosmic-rays nuclei. The need for a holistic treatment of gamma rays, cosmic rays, and magnetic fields serves as a unifying theme for these seemingly unrelated phenomena.

APA, Harvard, Vancouver, ISO, and other styles

9

Krennrich, Frank. "TeV GAMMA RAYS: OBSERVATIONS VERSUS EXPECTATIONS & THEORY." Acta Polytechnica 53, A (2013): 635–40. http://dx.doi.org/10.14311/ap.2013.53.0635.

Full text

Abstract:

The scope of this paper is to discuss two important questions relevant for TeV γ-ray astronomy; the pursuit to reveal the origin of cosmic rays in our galaxy, and the opacity of the universe in γ-rays. The origin of cosmic rays stipulated the field of TeV astronomy in the first place, and led to the development of the atmospheric Cherenkov technique; significant progress has been made in the last decade through the detection of several supernova remnants, the primary suspects for harboring the acceleration sites of cosmic rays. TeV γ-rays propagate mostly unhindered through the galactic plane, making them excellent probes of processes in SNRs and other galactic sources. Key results related to the SNR origin of cosmic rays are discussed. TeV γ-ray spectra from extragalactic sources experience significant absorption when traversing cosmological distances. The opacity of the universe to γ-rays above 10 GeV progressively increases with energy and redshift; the reason lies in their pair production with ambient soft photons from the extragalactic background light (EBL). While this limits the γ-ray horizon, it offers the opportunity to gain information about cosmology, i.e. the EBL intensity, physical conditions in intergalactic space, and potentially new interaction processes. Results and implications pertaining to the EBL are given.

APA, Harvard, Vancouver, ISO, and other styles

10

Schlickeiser, Reinhard. "Cosmic-Ray Transport and Acceleration." International Astronomical Union Colloquium 142 (1994): 926–36. http://dx.doi.org/10.1017/s0252921100078337.

Full text

Abstract:

AbstractWe review the transport and acceleration of cosmic rays concentrating on the origin of galactic cosmic rays. Quasi-linear theory for the acceleration rates and propagation parameters of charged test particles combined with the plasma wave viewpoint of modeling weak cosmic electromagnetic turbulence provides a qualitatively and quantitatively correct description of key observations. Incorporating finite frequency effects, dispersion, and damping of the plasma waves are essential in overcoming classical discrepancies with observations as the Kfit - Kql discrepancy of solar particle events. We show that the diffusion-convection transport equation in its general form contains spatial convection and diffusion terms as well as momentum convection and diffusion terms. In particular, the latter momentum diffusion term plays a decisive role in the acceleration of cosmic rays at super-Alfvénic supernova shock fronts, and in the acceleration of ultra-high-energy cosmic rays by distributed acceleration in our own galaxy.Subject headings: acceleration of particles — convection — cosmic rays — diffusion — shock waves

APA, Harvard, Vancouver, ISO, and other styles

11

Zank, G. P. "A cosmic-ray-driven plasma instability." Journal of Plasma Physics 41, no. 1 (1989): 89–95. http://dx.doi.org/10.1017/s0022377800013684.

Full text

Abstract:

The stability of the MHD equations describing the mutual interaction of cosmic rays, thermal plasma, magnetic field and Alfvén waves used in cosmic-ray-shock acceleration theory (e.g. McKenzie & Völk 1982) is analysed for linear compressive instabilities. It is found that the inclusion of wave effects implies that the forward propagating sub-Alfvénic mode is unstable on wavelength scales greater than 1 parsec. The role of the instability in astrophysical models is considered.

APA, Harvard, Vancouver, ISO, and other styles

12

Heintz, Evan, and Ellen G. Zweibel. "Galaxies at a Cosmic Ray Eddington Limit." Astrophysical Journal 941, no. 1 (2022): 78. http://dx.doi.org/10.3847/1538-4357/ac9e9e.

Full text

Abstract:

Abstract Cosmic rays have been shown to be extremely important in the dynamics of diffuse gas in galaxies, helping to maintain hydrostatic equilibrium, and serving as a regulating force in star formation. In this paper, we address the influence of cosmic rays on galaxies by re-examining the theory of a cosmic ray Eddington limit, first proposed by Socrates et al. and elaborated upon by Crocker et al. and Huang & Davis. A cosmic ray Eddington limit represents a maximum cosmic ray energy density above which the interstellar gas cannot be in hydrostatic equilibrium, resulting in a wind. In this paper, we continue to explore the idea of a cosmic ray Eddington limit by introducing a general framework that accounts for the circumgalactic environment and applying it to five galaxies that we believe to be a good representative sample of the star-forming galaxy population, using different cosmic ray transport models to determine what gives each galaxy the best chance to reach this limit. We show that, while an Eddington limit for cosmic rays does exist, for our five galaxies, the limit either falls at star formation rates that are much larger or gas densities that are much lower than each galaxy’s measured values. This suggests that cosmic ray pressure is not the main factor limiting the luminosity of starburst galaxies.

APA, Harvard, Vancouver, ISO, and other styles

13

Mertsch, P., and M. Ahlers. "Cosmic ray small-scale anisotropies in quasi-linear theory." Journal of Cosmology and Astroparticle Physics 2019, no. 11 (2019): 048. http://dx.doi.org/10.1088/1475-7516/2019/11/048.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Zhang, Ming. "A Markov Stochastic Process Theory of Cosmic‐Ray Modulation." Astrophysical Journal 513, no. 1 (1999): 409–20. http://dx.doi.org/10.1086/306857.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Munakata, K., and K. Nagashima. "A theory of cosmic ray anisotropies of solar origin." Planetary and Space Science 34, no. 1 (1986): 99–116. http://dx.doi.org/10.1016/0032-0633(86)90107-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Thielheim, K. O. "Cosmic Ray Particle Acceleration in Pulsar Magnetospheres." Symposium - International Astronomical Union 125 (1987): 555. http://dx.doi.org/10.1017/s0074180900161406.

Full text

Abstract:

A plausible approach to the theory of pulsars as cosmic ray particle accelerators is to integrate numerically the Lorentz-Dirac-equation, using the vacuum field of a rotating orthogonal magnetic dipole as a model field configuration. Typical parameter values are: angular velocity ω = 20 π/sec and magnetic dipole moment μ = 1030G cm3 (K.O. Thielheim, Proc. ESO-CERN Conf. 1986).

APA, Harvard, Vancouver, ISO, and other styles

17

Tatischeff, Vincent, and Stefano Gabici. "Particle Acceleration by Supernova Shocks and Spallogenic Nucleosynthesis of Light Elements." Annual Review of Nuclear and Particle Science 68, no. 1 (2018): 377–404. http://dx.doi.org/10.1146/annurev-nucl-101917-021151.

Full text

Abstract:

In this review, we first reassess the supernova remnant paradigm for the origin of Galactic cosmic rays in the light of recent cosmic-ray data acquired by the Voyager 1 spacecraft. We then describe the theory of light-element nucleosynthesis by nuclear interaction of cosmic rays with the interstellar medium and outline the problem of explaining the measured beryllium abundances in old halo stars of low metallicity with the standard model of the Galactic cosmic-ray origin. We then discuss the various cosmic-ray models proposed in the literature to account for the measured evolution of the light elements in the Milky Way, and point out the difficulties that they all encounter. It seems to us that, among all possibilities, the superbubble model provides the most satisfactory explanation for these observations.

APA, Harvard, Vancouver, ISO, and other styles

18

BLARD, P., D. BOURLES, J. LAVE, and R. PIK. "Applications of ancient cosmic-ray exposures: Theory, techniques and limitations." Quaternary Geochronology 1, no. 1 (2006): 59–73. http://dx.doi.org/10.1016/j.quageo.2006.06.003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Caprioli, Damiano. "Cosmic-ray acceleration in supernova remnants: non-linear theory revised." Journal of Cosmology and Astroparticle Physics 2012, no. 07 (2012): 038. http://dx.doi.org/10.1088/1475-7516/2012/07/038.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Wittor, D., F. Vazza, D. Ryu, and H. Kang. "Limiting the shock acceleration of cosmic ray protons in the ICM." Monthly Notices of the Royal Astronomical Society: Letters 495, no. 1 (2020): L112—L117. http://dx.doi.org/10.1093/mnrasl/slaa066.

Full text

Abstract:

ABSTRACT Observations of large-scale radio emissions prove the existence of shock accelerated cosmic ray electrons in galaxy clusters, while the lack of detected γ-rays limits the acceleration of cosmic ray protons in galaxy clusters. This challenges our understanding of how diffusive shock acceleration works. In this work, we couple the most updated recipes for shock acceleration in the intracluster medium to state-of-the-art magnetohydrodynamical simulations of massive galaxy clusters. Furthermore, we use passive tracer particles to follow the evolution of accelerated cosmic rays. We show that when the interplay between magnetic field topology and the feedback from accelerated cosmic rays is taken into account, the latest developments of particle acceleration theory give results that are compatible with observational constraints.

APA, Harvard, Vancouver, ISO, and other styles

21

Wandel, Amri. "Supernova Remnants and the ISM: Constraints from Cosmic-Ray Acceleration." International Astronomical Union Colloquium 101 (1988): 325–29. http://dx.doi.org/10.1017/s0252921100102581.

Full text

Abstract:

AbstractSupernova remnants can reaccelerate cosmic rays and modify their distribution during the cosmic ray propagation in the galaxy. Cosmic ray observations (in particular the boron-to-carbon data) strongly limit the permitted amount of reacceleration, which is used to set an upper limit on the expansion of supernova remnants, and a lower limit on the effective density of the ISM swept up by supernova shocks. The constraint depends on the theory of cosmic ray propagation: the standard Leaky Box model requires a high effective density, > 1cm−3, and is probably inconsistent with the present picture of the ISM. Modifying the Leaky Box model to include a moderate amount of weak-shock reacceleration, a self consistent solution is found, where the effective density in this solution is ≈ 0.1 cm−3, which implies efficient evaporation of the warm ISM component by young supernova remnants, during most of their supersonic expansion.

APA, Harvard, Vancouver, ISO, and other styles

22

Fornieri, Ottavio, Daniele Gaggero, Silvio Sergio Cerri, Pedro De La Torre Luque, and Stefano Gabici. "The theory of cosmic ray scattering on pre-existing MHD modes meets data." Monthly Notices of the Royal Astronomical Society 502, no. 4 (2021): 5821–38. http://dx.doi.org/10.1093/mnras/stab355.

Full text

Abstract:

ABSTRACT We present a comprehensive study about the phenomenological implications of the theory describing Galactic cosmic ray scattering on to magnetosonic and Alfvénic fluctuations in the GeV−PeV domain. We compute a set of diffusion coefficients from first principles, for different values of the Alfvénic Mach number and other relevant parameters associated with both the Galactic halo and the extended disc, taking into account the different damping mechanisms of turbulent fluctuations acting in these environments. We confirm that the scattering rate associated with Alfvénic turbulence is highly suppressed if the anisotropy of the cascade is taken into account. On the other hand, we highlight that magnetosonic modes play a dominant role in Galactic confinement of cosmic rays up to PeV energies. We implement the diffusion coefficients in the numerical framework of the dragon code, and simulate the equilibrium spectrum of different primary and secondary cosmic ray species. We show that, for reasonable choices of the parameters under consideration, all primary and secondary fluxes at high energy (above a rigidity of $\simeq 200 \, \mathrm{GV}$) are correctly reproduced within our framework, in both normalization and slope.

APA, Harvard, Vancouver, ISO, and other styles

23

Tjus, Julia Becker. "Plasmas, particles and photons—spotlights on multimessenger astronomy." Plasma Physics and Controlled Fusion 64, no. 4 (2022): 044013. http://dx.doi.org/10.1088/1361-6587/ac57ce.

Full text

Abstract:

Abstract During the past decennia, progress in the area of high-energy astroparticle physics was exceptional, mainly due to the great success of the bridging of particle- and astrophysics both in theory and in the instrumentation of astroparticle physics observatories. Multimessenger data coming from charged cosmic-ray-, gamma-ray- and neutrino-observatories start to shed more and more light on the nature and origin of cosmic rays. At the same time, the development of methods for the investigation of cosmic-ray transport, acceleration and interaction has advanced to the true potential of tying these different pieces of multimessenger data together, this way closing in on the origin of cosmic rays. In recent years, this rapid interplay between modeling and observations has made it clear that it is essential to add the ingredient of plasma physics to the problem. It has been shown that even the interpretation of data of highly relativistic cosmic rays at TeV energies and above is in need of a proper modeling of the plasma physics involved. One of the most important examples is the understanding of wave-particle interactions. In simulations of cosmic-ray transport in the Galaxy, the cosmic-ray diffusion coefficient is typically approximated with a Kolmogorov-type cascade model, resulting in an energy-dependent parallel diffusion coefficient κ ∥ ∝ E γ with γ = 1 / 3 . Here, we show how the energy dependence of the diffusion coefficient can be investigated systematically as a function of δ B / B . The complex energy behavior that goes well beyond a simple powerlaw interpretation will be presented together with a formal definition of an energy range that indeed can be approximated as a powerlaw. These results are applied to cosmic-ray transport in the Milky Way. Finally, the transition between the ballistic and diffusive regime will be investigated for astrophysical sources with special focus on relativistic plasmoids of active galaxies.

APA, Harvard, Vancouver, ISO, and other styles

24

Wibig, Tadeusz, and Arnold W. Wolfendale. "Cosmic ray contributions to the WMAP polarization data on the cosmic microwave background." International Journal of Modern Physics D 25, no. 03 (2016): 1650029. http://dx.doi.org/10.1142/s0218271816500292.

Full text

Abstract:

We have updated our analysis of the 9-year WMAP data using the collection of polarization maps looking for the presence of additional evidence for a finite ‘cosmic ray (CR) foreground’ for the cosmic microwave background (CMB). We have given special attention to high Galactic latitudes, where the recent BICEP2 findings were reported although very recent Planck data claims that dust is prevalent, thus nullifying the BICEP2 results. The method of examining the correlation with the observed gamma ray flux proposed in our earlier papers and applied to the polarization data shows that the foreground related to CRs is still observed even at high Galactic latitudes and conclusions about gravitational waves are not yet secure. Theory has it that there is important information about inflationary gravitational waves in the fine structure of the CMB polarization properties (polarization vector and angle) and it is necessary to examine further the conclusions that can be gained from studies of the CMB maps, in view of the disturbing foreground effects.

APA, Harvard, Vancouver, ISO, and other styles

25

Mesinger, Andrei. "Reionization and Cosmic Dawn: theory and simulations." Proceedings of the International Astronomical Union 12, S333 (2017): 3–11. http://dx.doi.org/10.1017/s1743921317011139.

Full text

Abstract:

AbstractWe highlight recent progress in the sophistication and diversification of the simulations of cosmic dawn and reionization. The application of these modeling tools to recent observations has allowed us narrow down the timing of reionization. The midpoint of reionization is constrained to z = 7.6−0.7+0.8 (1 σ), with the strongest constraints coming from the optical depth to the CMB measured with the Planck satellite and the first detection of ongoing reionization from the spectra of the z = 7.1 QSOs ULASJ1120+0641. However, we still know virtually nothing about the astrophysical sources during the first billion years. The revolution in our understanding will be led by upcoming interferometric observations of the cosmic 21-cm signal. The properties of the sources and sinks of UV and X-ray photons are encoded in the 3D patterns of the signal. The development of Bayesian parameter recovery techniques, which tap into the wealth of the 21-cm signal, will soon usher in an era of precision astrophysical cosmology.

APA, Harvard, Vancouver, ISO, and other styles

26

Huege, T. "Simulations and theory of radio emission from cosmic ray air showers." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 604, no. 1-2 (2009): S57—S63. http://dx.doi.org/10.1016/j.nima.2009.03.165.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Schlickeiser, Reinhard, and Ulrich Achatz. "Cosmic-ray particle transport in weakly turbulent plasmas. Part 1. Theory." Journal of Plasma Physics 49, no. 1 (1993): 63–77. http://dx.doi.org/10.1017/s0022377800016822.

Full text

Abstract:

We consider a quasi-linear theory for the acceleration rates and propagation parameters of charged test particles in weakly turbulent electromagnetic plasmas. The similarity between two recent approaches to modelling of therandom electromagnetic field is demonstrated. It is shown that both the concept of dynamical magnetic turbulence and the concept of superposition of individual plasma modes lead to particle Fokker—Planck coefficients in which the sharp delta functions describing the resonant interaction of the particles have to be replaced by Breit—Wigner-type resonance functions, which are controlled by the dynamical turbulence decay time and the wave-damping time respectively. The resulting resonance broadening will significantly change the evaluation of cosmic-ray transport parameters.

APA, Harvard, Vancouver, ISO, and other styles

28

Blandford, Roger, and David Eichler. "Particle acceleration at astrophysical shocks: A theory of cosmic ray origin." Physics Reports 154, no. 1 (1987): 1–75. http://dx.doi.org/10.1016/0370-1573(87)90134-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Busoni, Giorgio, and Laura Prati. "Theory of Evolution Systems Applied to a Cosmic Ray Diffusion Model." Transport Theory and Statistical Physics 40, no. 1 (2011): 23–67. http://dx.doi.org/10.1080/00411450.2011.563813.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Reichherzer, P., J. Becker Tjus, E. G. Zweibel, L. Merten, and M. J. Pueschel. "Turbulence-level dependence of cosmic ray parallel diffusion." Monthly Notices of the Royal Astronomical Society 498, no. 4 (2020): 5051–64. http://dx.doi.org/10.1093/mnras/staa2533.

Full text

Abstract:

ABSTRACT Understanding the transport of energetic cosmic rays belongs to the most challenging topics in astrophysics. Diffusion due to scattering by electromagnetic fluctuations is a key process in cosmic ray transport. The transition from a ballistic to a diffusive-propagation regime is presented in direct numerical calculations of diffusion coefficients for homogeneous magnetic field lines subject to turbulent perturbations. Simulation results are compared with theoretical derivations of the parallel diffusion coefficient’s dependences on the energy and the fluctuation amplitudes in the limit of weak turbulence. The present study shows that the widely used extrapolation of the energy scaling for the parallel diffusion coefficient to high turbulence levels predicted by quasi-linear theory does not provide a universally accurate description in the resonant-scattering regime. It is highlighted here that the numerically calculated diffusion coefficients can be polluted for low energies due to missing resonant interaction possibilities of the particles with the turbulence. Five reduced-rigidity regimes are established, which are separated by analytical boundaries derived in this work. Consequently, a proper description of cosmic ray propagation can only be achieved by using a turbulence-level-dependent diffusion coefficient and can contribute to solving the Galactic cosmic ray gradient problem.

APA, Harvard, Vancouver, ISO, and other styles

31

Berezhko, E. G., G. Pühlhofer та H. J. Völk. "Theory of cosmic ray and γ-ray production in the supernova remnant RX J0852.0-4622". Astronomy & Astrophysics 505, № 2 (2009): 641–54. http://dx.doi.org/10.1051/0004-6361/200809473.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

HESS, PETER O., and WALTER GREINER. "PSEUDO-COMPLEX FIELD THEORY." International Journal of Modern Physics E 16, no. 06 (2007): 1643–79. http://dx.doi.org/10.1142/s0218301307006964.

Full text

Abstract:

A new formulation of field theory is presented, based on a pseudo-complex description. An extended group structure is introduced, implying a minimal scalar length, rendering the theory regularized a la Pauli–Villars. Cross sections are calculated for the scattering of an electron at an external Coulomb field and the Compton scattering. Deviations due to a smallest scalar length are determined. The theory also permits a modification of the minimal coupling scheme, resulting in a generalized dispersion relation. A shift of the Greisen–Zatsepin–Kuzmin (GZK) limit of the cosmic ray spectrum is the consequence.

APA, Harvard, Vancouver, ISO, and other styles

33

Dorfi, E. A. "Evolution of Supernova Remnants with Cosmic Rays and Radiative Cooling." International Astronomical Union Colloquium 142 (1994): 841–44. http://dx.doi.org/10.1017/s0252921100078192.

Full text

Abstract:

AbstractRecent numerical models for SNR evolution are presented, including first-order Fermi acceleration with injection of suprathermal particles at the shock wave, heating due to dissipation of Alfvén waves in the precursor region and radiative cooling of the thermal plasma. The X-ray fluxes obtained from these SNR models show significant differences depending on the acceleration efficiency of cosmic rays. γ-ray fluxes are calculated originating from π0-decay of pions generated by collisions of the high-energy particles with the thermal plasma. Cooling of the thermal plasma and dissipation of Alfvén waves in the precursor are important to determine the final amount of the explosion energy ESN which is transferred into cosmic rays.Subject headings: acceleration of particles — cosmic rays — gamma rays: theory — shock waves — supernova remnants

APA, Harvard, Vancouver, ISO, and other styles

34

Plebaniak, Zbigniew, and Tadeusz Wibig. "EAS longitudinal development distribution parameters for different extrapolations of the nuclei intaraction cross section to the very high energy domain." EPJ Web of Conferences 208 (2019): 08016. http://dx.doi.org/10.1051/epjconf/201920808016.

Full text

Abstract:

Determination of the primary particle mass using air fluorescence or a Cherenkov detector array is one of the most difficult task of experimental cosmic ray studies. The information about the primary particle mass is a compound of the produced particle multiplicity, inelasticity, interaction cross-section and many other parameters, thus it is necessary to compare registered showers with sophisticated Monte-Carlo simulation results. In this work we present results of the studies of at least three possible ways of extrapolating proton- Nucleus and Nucleus-Nucleus cross sections to cosmic ray energies based on the Glauber theory. They are compared with experimental accelerator and cosmic ray data for the proton-air cross section. We also present results of the EAS development with the most popular high-energy interaction models adopted in the CORSIKA program with our cross section extrapolations. The average position of the shower maximum and the width of its distribution are compared with experimental data and some discussion is given.

APA, Harvard, Vancouver, ISO, and other styles

35

Burde, Georgy I. "Lorentz Violation by the Preferred Frame Effects and Cosmic and Gamma Ray Propagation." Galaxies 9, no. 4 (2021): 119. http://dx.doi.org/10.3390/galaxies9040119.

Full text

Abstract:

The ‘relativity with a preferred frame’, designed to reconcile the relativity principle with the existence of the cosmological preferred frame, incorporates the preferred frame at the level of special relativity (SR) while retaining the fundamental spacetime symmetry, which, in the standard SR, manifests itself as Lorentz invariance. In this paper, the processes, accompanying the propagation of cosmic rays and gamma rays through the background radiation from distant sources to Earth, are considered on the basis of particle dynamics and electromagnetic field dynamics developed within the framework of the ‘relativity with a preferred frame’. Applying the theory to the photopion-production and pair-production processes shows that the modified particle dynamics and electrodynamics lead to measurable signatures in the observed cosmic and gamma-ray spectra which can provide an interpretation of some puzzling features found in the observational data. Other processes responsible for gamma-ray attenuation are considered. It is found, in particular, that electromagnetic cascades, developing on cosmic microwave background and extragalactic background light, may be reduced or suppressed due to the preferred frame effects which should influence the shape of the very high-energy gamma-ray spectra. Other possible observational consequences of the theory, such as the birefringence of light propagating in vacuo and dispersion, are discussed.

APA, Harvard, Vancouver, ISO, and other styles

36

Starodubtsev, Sergei. "Shape of spectrum of galactic cosmic ray intensity fluctuations." Solnechno-Zemnaya Fizika 8, no. 2 (2022): 78–83. http://dx.doi.org/10.12737/szf-82202211.

Full text

Abstract:

The impact of solar wind plasma on fluxes of galactic cosmic rays (CR) penetrating from the outside into the heliosphere with energies above ~1 GeV leads to temporal variations in the CR intensity in a wide frequency range. Cosmic rays being charged particles, their modulation occurs mainly under impacts of the interplanetary magnetic field. It is well known that the observed spectrum of interplanetary magnetic field (IMF) fluctuations in a wide frequency range ν from ~10–7 to ~10 Hz has a pronounced falling character and consists of three sections: energy, inertial, and dissipative. Each of them is described by the power law PIMF(ν)~ν–α, while the IMF spectrum index α increases with increasing frequency. The IMF fluctuations in each of these sections are also characterized by properties that depend on their nature. Also known are established links between fluctuation spectra of the interplanetary magnetic field and galactic cosmic rays in the case of modulation of the latter by Alfvén or fast magnetosonic waves. The theory predicts that fluctuation spectra of cosmic rays should also be described by the power law PCR(ν)~ν–γ. However, the results of many years of SHICRA SB RAS research into the nature and properties of cosmic ray intensity fluctuations based on data from neutron monitors at stations with different geomagnetic cut-offs RC from 0.5 to 6.3 GV show that the observed spectrum of fluctuations in galactic cosmic ray intensity in the frequency range above 10–4 Hz becomes flat, i.e. it is similar to white noise. This fact needs to be realized and explained. This paper reports the results of research into the shape of the spectrum of galactic cosmic ray intensity fluctuations within a frequency range ν from ~10–6 to ~1 Hz and compares them with model calculations of white noise spectra, using measurement data from the neutron monitor of the Apatity station. A possible physical explanation has been given for the observed shape of the cosmic ray fluctuation spectrum on the basis of the known mechanisms of their modulation in the heliosphere.

APA, Harvard, Vancouver, ISO, and other styles

37

Shapiro, V. D., K. B. Quest, and M. Okolicsanyi. "Non-resonant firehose instability: Consequences for the theory of cosmic ray acceleration." Geophysical Research Letters 25, no. 6 (1998): 845–48. http://dx.doi.org/10.1029/98gl00467.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Berezhko, E. G., and H. J. Völk. "Theory of cosmic ray production in the supernova remnant RX J1713.7-3946." Astronomy & Astrophysics 451, no. 3 (2006): 981–90. http://dx.doi.org/10.1051/0004-6361:20054595.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Ellison, Donald C., and David Eichler. "Relativistic Cosmic-Ray Spectra in the Fully Nonlinear Theory of Shock Acceleration." Physical Review Letters 55, no. 24 (1985): 2735–38. http://dx.doi.org/10.1103/physrevlett.55.2735.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Hussein, M., and A. Shalchi. "DETAILED NUMERICAL INVESTIGATION OF THE BOHM LIMIT IN COSMIC RAY DIFFUSION THEORY." Astrophysical Journal 785, no. 1 (2014): 31. http://dx.doi.org/10.1088/0004-637x/785/1/31.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Zhang, Ming. "A Path Integral Approach to the Theory of Heliospheric Cosmic‐Ray Modulation." Astrophysical Journal 510, no. 2 (1999): 715–25. http://dx.doi.org/10.1086/306624.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Stepanov, Rodion, A. Fletcher, A. Shukurov, R. Beck, L. La Porta, and F. S. Tabatabaei. "Relative distributions of cosmic ray electrons and magnetic fields in the ISM." Proceedings of the International Astronomical Union 4, S259 (2008): 93–94. http://dx.doi.org/10.1017/s1743921309030130.

Full text

Abstract:

AbstractWe calculate the relative magnitudes of the fluctuations in total synchrotron intensity in the interstellar medium, both from observations and from theory under various assumptions about the correlation or anticorrelation between cosmic rays and interstellar magnetic fields. The results are inconsistent with local energy equipartition between cosmic rays and magnetic fields. The distribution of cosmic rays must be rather uniform at scales of order 1 kpc, whereas interstellar magnetic fields vary at much smaller scales.

APA, Harvard, Vancouver, ISO, and other styles

43

CHEN, SHAO-XIA, and ZHAO-YU YANG. "NONCOMMUTATIVITY AS A POSSIBLE ORIGIN OF THE ULTRAHIGH ENERGY COSMIC RAY AND THE TeV-PHOTON PARADOXES." Modern Physics Letters A 18, no. 40 (2003): 2913–19. http://dx.doi.org/10.1142/s0217732303012398.

Full text

Abstract:

In this paper, we present a general modified dispersion relation derived from q-deformed noncommutative theory and apply it to the ultrahigh energy cosmic ray and the TeV-photon paradoxes — threshold anomalies. Our purpose is not only trying to solve these puzzles by noncommutative theory but also to support noncommutative theory through the coincidence of the region in the parameter space for resolving the threshold anomalies with the one from the q-deformed noncommutative theory.

APA, Harvard, Vancouver, ISO, and other styles

44

Biermann, Peter L., Philipp P. Kronberg, Michael L. Allen, Athina Meli, and Eun-Suk Seo. "The Origin of the Most Energetic Galactic Cosmic Rays: Supernova Explosions into Massive Star Plasma Winds." Galaxies 7, no. 2 (2019): 48. http://dx.doi.org/10.3390/galaxies7020048.

Full text

Abstract:

We propose that the high energy Cosmic Ray particles up to the upturn commonly called the ankle, from around the spectral turn-down commonly called the knee, mostly come from Blue Supergiant star explosions. At the upturn, i.e., the ankle, Cosmic Rays probably switch to another source class, most likely extragalactic sources. To show this we recently compiled a set of Radio Supernova data where we compute the magnetic field, shock speed and shock radius. This list included both Blue and Red Supergiant star explosions; both data show the same magnetic field strength for these two classes of stars despite very different wind densities and velocities. Using particle acceleration theory at shocks, those numbers can be transformed into characteristic ankle and knee energies. Without adjusting any free parameters both of these observed energies are directly indicated by the supernova data. In the next step in the argument, we use the Supernova Remnant data of the starburst galaxy M82. We apply this analysis to Blue Supergiant star explosions: The shock will race to their outer edge with a magnetic field that is observed to follow over several orders of magnitude B ( r ) × r ∼ c o n s t . , with in fact the same magnetic field strength for such stellar explosions in our Galaxy, and other galaxies including M82. The speed is observed to be ∼0.1 c out to about 10 16 cm radius in the plasma wind. The Supernova shock can run through the entire magnetic plasma wind region at full speed all the way out to the wind-shell, which is of order parsec scale in M82. We compare and identify the Cosmic Ray spectrum in other galaxies, in the starburst galaxy M82 and in our Galaxy with each other; we suggest how Blue Supergiant star explosions can provide the Cosmic Ray particles across the knee and up to the ankle energy range. The data from the ISS-CREAM (Cosmic Ray Energetics and Mass Experiment at the International Space Station) mission will test this cosmic ray concept which is reasonably well grounded in two independent radio supernova data sets. The next step in developing our understanding will be to obtain future more accurate Cosmic Ray data near to the knee, and to use unstable isotopes of Cosmic Ray nuclei at high energy to probe the “piston” driving the explosion. We plan to incorporate these data with the physics of the budding black hole which is probably forming in each of these stars.

APA, Harvard, Vancouver, ISO, and other styles

45

AMELINO-CAMELIA, GIOVANNI. "KINEMATICAL SOLUTION OF THE UHE-COSMIC-RAY PUZZLE WITHOUT A PREFERRED CLASS OF INERTIAL OBSERVERS." International Journal of Modern Physics D 12, no. 07 (2003): 1211–26. http://dx.doi.org/10.1142/s0218271803003645.

Full text

Abstract:

Among the possible explanations for the puzzling observations of cosmic rays above the GZK cutoff there is growing interest in the ones that represent kinematical solutions, based either on general formulations of particle physics with small violations of Lorentz symmetry or on a quantum-gravity-motivated scheme for the breakdown of Lorentz symmetry. An unappealing aspect of these cosmic-ray-puzzle solutions is that they require the existence of a preferred class of inertial observers. Here I propose a new kinematical solution of the cosmic-ray puzzle, which does not require the existence of a preferred class of inertial observers. My proposal is a new example of a type of relativistic theories, the so-called "doubly-special-relativity" theories, which have already been studied extensively over the last two years. The core ingredient of the proposal is a deformation of Lorentz transformations in which also the Planck scale Ep (in addition to the speed-of-light scale c) is described as an invariant. Just like the introduction of the invariant c requires a deformation of the Galileian transformations into the Lorentz transformations, the introduction of the invariant Ep requires a deformation of the Lorentz transformations, but there is no special class of inertial observers. The Pierre Auger Observatory and the GLAST space telescope should play a key role in future developments of these investigations. I also emphasize that the doubly-special-relativity theory here proposed, besides providing a solution for the cosmic-ray puzzle, is also the first doubly-special-relativity theory with a natural description of macroscopic bodies, and may find applications in the context of a recently-proposed dark-energy scenario.

APA, Harvard, Vancouver, ISO, and other styles

46

Biteau, Jonathan, and Manuel Meyer. "Gamma-Ray Cosmology and Tests of Fundamental Physics." Galaxies 10, no. 2 (2022): 39. http://dx.doi.org/10.3390/galaxies10020039.

Full text

Abstract:

The propagation of gamma-rays over cosmological distances is the subject of extensive theoretical and observational research at GeV and TeV energies. The mean free path of gamma-rays in the cosmic web is limited above 100 GeV due to the production of electrons and positrons on the cosmic optical and infrared backgrounds. Electrons and positrons cool in the intergalactic medium while gyrating in its magnetic fields, which could cause either its global heating or the production of lower-energy secondary gamma-rays. The energy distribution of gamma-rays surviving the cosmological journey carries observed absorption features that gauge the emissivity of baryonic matter over cosmic time, constrain the distance scale of ΛCDM cosmology, and limit the alterations of the interaction cross section. Competitive constraints are, in particular, placed on the cosmic star-formation history as well as on phenomena expected from quantum gravity and string theory, such as the coupling to hypothetical axion-like particles or the violation of Lorentz invariance. Recent theoretical and observational advances offer a glimpse of the multi-wavelength and multi-messenger path that the new generation of gamma-ray observatories is about to open.

APA, Harvard, Vancouver, ISO, and other styles

47

Sinitsyna, V. G., S. S. Borisov, R. M. Mirzafatikhov, and V. Y. Sinitsyna. "Cosmic ray origin: Supernova remnants through the electromagnetic spectrum." EPJ Web of Conferences 208 (2019): 04006. http://dx.doi.org/10.1051/epjconf/201920804006.

Full text

Abstract:

Supernova Remnants have long been considered as unique candidates for cosmic-ray sources. Recent observations of several SNRs in X-rays and TeV gamma-rays will help in solving the problem of the origin of cosmic rays and are key to understanding the mechanism of particle acceleration at a propagating shock wave. The observation results of Galactic shell-type supernova remnants at different evolution stages Cas A, Tycho's SNR, γCygni SNR, IC 443 and G166.0+4.3 by the SHALON mirror Cherenkov telescope are presented. For each SNR the SHALON observation results are given with its spectral energy distribution compared with other experimental data and images by SHALON together with data from X-ray by Chandra and radio-data by Canadian Galactic Plane Survey DRAO (CGPS). The comparison of the source's morphology in different energy bands could reveal its essential features as a forward and reverse shock or the location of swept out dense molecular cloud. The experimental data presented here have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy 800 GeV-100 TeV gamma-rays in Tycho's SNR, Cas A and IC 443. Also the collected experimental data help to make clear the origin of TeV gamma-ray emission in the SNRs like γCygni SNR and G166.0+4.3.

APA, Harvard, Vancouver, ISO, and other styles

48

Casanova, S., and R. Schlickeiser. "COSMIC-RAY TRANSPORT THEORY IN PARTIALLY TURBULENT SPACE PLASMAS WITH COMPRESSIBLE MAGNETIC TURBULENCE." Astrophysical Journal 745, no. 2 (2012): 153. http://dx.doi.org/10.1088/0004-637x/745/2/153.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Shalchi, A., and M. Gammon. "Perturbation theory based solution of the pitch-angle dependent cosmic ray diffusion equation." Advances in Space Research 63, no. 1 (2019): 653–64. http://dx.doi.org/10.1016/j.asr.2018.09.029.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Dorman, L. I. "Prediction of galactic cosmic ray intensity variation for a few (up to 10-12) years ahead on the basis of convection-diffusion and drift model." Annales Geophysicae 23, no. 9 (2005): 3003–7. http://dx.doi.org/10.5194/angeo-23-3003-2005.

Full text

Abstract:

Abstract. We determine the dimension of the Heliosphere (modulation region), radial diffusion coefficient and other parameters of convection-diffusion and drift mechanisms of cosmic ray (CR) long-term variation, depending on particle energy, the level of solar activity (SA) and general solar magnetic field. This important information we obtain on the basis of CR and SA data in the past, taking into account the theory of convection-diffusion and drift global modulation of galactic CR in the Heliosphere. By using these results and the predictions which are regularly published elsewhere of expected SA variation in the near future and prediction of next future SA cycle, we may make a prediction of the expected in the near future long-term cosmic ray intensity variation. We show that by this method we may make a prediction of the expected in the near future (up to 10-12 years, and may be more, in dependence for what period can be made definite prediction of SA) galactic cosmic ray intensity variation in the interplanetary space on different distances from the Sun, in the Earth's magnetosphere, and in the atmosphere at different altitudes and latitudes.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Cosmic-ray theory'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles