Statistical Discrete-Source Model of Local Cosmic Rays

Ramaty, R.; Reames, D. V.; Lingenfelter, R. E.

doi:10.1103/physrevlett.24.913

Cited by 25 publications

(7 citation statements)

References 7 publications

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“…Hillas and Ouldridge 16 arrive at a similar conclusion and point out that previous anisotropy measurements at lower energy (either a lower limit or an actual anisotropy) show an anisotropy that increases as a function of increasing energy proportional to the presumed galactic leakage I interpret isotropy along the lines originally proposed by Ramaty, Reames, and Lingenfelter, 17 where a combination of source distribution, frequency, and diffusion gives rise to a limiting statistical probability of anisotropy. What has been added to this model is a presumed isotropic extragalactic flux that becomes important above E >3 xlO 18 eV and local sources of flatter spectrum.…”

supporting

confidence: 55%

Origin of Very High-Energy Cosmic Rays

Colgate

1975

Phys. Rev. Lett.

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supporting

confidence: 55%

Origin of Very High-Energy Cosmic Rays

Colgate

1975

Phys. Rev. Lett.

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“…Reality is, however, otherwise with primary CRs produced in and about highly localised regions, e.g., supernova remnants (SNRs), which have finite lifetimes. The injection and propagation in the ISM of CRs produced by discrete (time/space) sources has, in fact, been investigated since the late 1960s (e.g., Lingenfelter 1969;Lingenfelter & Higdon 1973;Lingenfelter & Ramaty 1971;Ramaty et al 1970). A "standard" picture based on these ideas has emerged for interpreting local CR fluxes, particularly for the high-quality CR electron/positron data now available.…”

Section: Introductionmentioning

confidence: 99%

Deciphering Residual Emissions: Time-dependent Models for the Nonthermal Interstellar Radiation from the Milky Way

Porter¹,

Jóhannesson²,

Moskalenko³

2019

ApJ

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Cosmic rays (CRs) in the Galaxy are an important dynamical component of the interstellar medium (ISM) that interact with the other major components (interstellar magnetic and radiation fields, and gas) to produce broadband interstellar emissions that span the electromagnetic spectrum. The standard modelling of CR propagation and production of the associated emissions is based on a steady-state assumption, where the CR source spatial density is described using a smoothly varying function of position that does not evolve with time. While this is a convenient approximation, reality is otherwise where primary CRs are produced in and about highly localised regions, e.g., supernova remnants, which have finite lifetimes. In this paper we use the latest version of the GALPROP CR propagation code to model time-dependent CR injection and propagation through the ISM from a realistic three-dimensional discretised CR source density distribution, together with full three-dimensional models for the other major ISM components, and make predictions of the associated broadband non-thermal emissions. We compare the predictions for the discretised and equivalent steady-state model, finding that the former predicts novel features in the broadband non-thermal emissions that are absent for the steady-state case. Some of features predicted by the discretised model may be observable in all-sky observations made by WMAP and Planck, the recently launched eROSITA, the Fermi-LAT, and ground-based observations by HESS, HAWC, and the forthcoming CTA. The non-thermal emissions predicted by the discretised model may also provide explanations of puzzling anomalies in high-energy γ-ray data, such as the Fermi-LAT north/south asymmetry and residuals like the so-called "Fermi bubbles".

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“…By counting tracks of heavy cosmic rays in meteorites of known cosmic ray exposure ages, it has been shown that the relative abundances of Fe and the trans-iron nuclei have not drastically changed over the last ~ 10 7 yr (Cantelaube et al, 1967;Maurette et al, 1968;Price et al, 1971). A sufficiently careful study has not yet been made that one could rule out fluctuations of the kind predicted by Ramaty et al (1970) for the extremely heavy nuclei such as U that have very short mean free paths for collisions with interstellar gas. They showed that time-variations of the order of a factor two in the fluxes of the heaviest cosmic rays would be expected if they come from point sources in space and time (e.g.…”

Section: Time Dependence Of Compositionmentioning

confidence: 99%

A cosmochemical view of cosmic rays and solar particles

Price

1973

Space Sci Rev

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The composition of cosmic rays and solar particles is reviewed with emphasis on the question of whether they are representative samples of Galactic and solar matter. The composition of solar particles changes with energy and from flare to flare. A strong excess of heavy elements at energies below a few MeV/nuc decreases with energy, and at energies above ~ 15 MeV/nuc the composition of solar particles resembles that of galactic cosmic rays somewhat better than that of the solar atmosphere. The elements Ne through Pb have remarkably similar abundances in cosmic ray sources and in the matter of the solar system. The lighter elements are depleted in cosmic rays, whereas U and Th may be enriched or not, depending on whether the meteoritic or solar abundance of Th is used. Two prototype sources of cosmic rays are considered: gas with solar system composition but enriched in elements with Z>8 during acceleration and emission (by analogy with solar particle emission), and highly evolved matter enriched in r-process elements such as U, Th and transuranic elements. The energy-dependence of cosmic ray composition suggests that both sources may contribute at different energies.

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Statistical Discrete-Source Model of Local Cosmic Rays

Cited by 25 publications

References 7 publications

Origin of Very High-Energy Cosmic Rays

Origin of Very High-Energy Cosmic Rays

Deciphering Residual Emissions: Time-dependent Models for the Nonthermal Interstellar Radiation from the Milky Way

A cosmochemical view of cosmic rays and solar particles

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