TeV cosmic-ray proton and helium spectra in the myriad model II

Liu, Wei; Salati, Pierre; Chen, Xuelei

doi:10.1088/1674-4527/15/1/002

Cited by 12 publications

(11 citation statements)

References 53 publications

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“…Statistical descriptions based on Galaxy-wide ensemble of discrete sources have been used to also interpret the electron data and CR nuclei fluxes (Higdon & Lingenfelter 2003;Taillet et al 2004;Mertsch 2011;Bernard et al 2012;Liu et al 2015;Miyake et al 2015;Genolini et al 2017;Mertsch 2018;Ptuskin et al 2006). Unsurprisingly given the lack of directionality for the CR fluxes and the large parametric uncertainty for such descriptions, a unique distribution of sources explaining the CR data, particularly for the high energies where spectral features are most evident, has proved elusive.…”

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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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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“…Reality is, however, otherwise with primary CRs produced in and about highly localised regions, e.g., SNRs, which have finite lifetimes. This discretised picture for the CR sources has been explored for a long time for modelling the local CR fluxes (e.g., Higdon & Lingenfelter 2003;Taillet et al 2004;Mertsch 2011Mertsch , 2018Bernard et al 2012;Liu et al 2015;Miyake et al 2015;Genolini et al 2017;Ptuskin et al 2006). However, the modelling for the ensuent broadband non-thermal emissions from ensembles of such sources across the entire MW has only been recently investigated (Porter et al 2019).…”

Section: Discretised Source Ensemble Interstellar Emission Modelmentioning

confidence: 99%

The GALPROP Cosmic-ray Propagation and Non-thermal Emissions Framework: Release v57

Porter,

Johannesson,

Moskalenko

2021

Preprint

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The past decade has brought impressive advances in astrophysics of cosmic rays (CRs) and multi-wavelength 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 (DM) and new physics. Understanding the astrophysical backgrounds to better precision than the observed data is vital in moving to this new territory. The state-of-the-art CR propagation code called GALPROP is designed to address exactly this challenge. Having 25 years of development behind it, the GALPROP framework has become a de-facto standard in 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 modelling framework. The range of its physical validity covers 18 orders of magnitude in energy, from sub-keV to PeV energies for particles and from µeV to PeV energies for photons. The framework and the datasets 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, further developments of its initially auxiliary datasets that grew into independent studies of the Galactic structure-distributions of gas, dust, radiation and magnetic fields-as well as the extension of its modelling capabilities. Example applications included with the distribution illustrating usage of the new features are also described.

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“…Observations of proton, helium, and heavier nuclei also show remarkable hardenings at energies above a few hundred GeV/nucleon [34][35][36][37][38][39]. The hadronic hardening may be ascribed to source model [40][41][42][43][44][45][46], transport effect [47][48][49][50][51][52], or production mechanism [53,54]. Most recently, AMS-02 collaboration released the measurements of antiproton-to-proton ratio, which shows a flat behavior up to ∼ 400 GeV [55].…”

Section: Introductionmentioning

confidence: 99%

Excesses of cosmic ray spectra from a single nearby source

Liu

Lin

et al. 2017

Phys. Rev. D

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Growing evidence reveals universal hardening on various cosmic ray spectra, e.g. proton, positron, as well as antiproton fraction. Such universality may indicate they have a common origin. In this paper, we argue that these widespread excesses can be accounted for by a nearby supernova remnant surrounded by a giant molecular cloud. Secondary cosmic rays (p, e + ) are produced through the collisions between the primary cosmic ray nuclei from this supernova remnant and the molecular gas. Different from the background, which is produced by the ensemble of large amount of sources in the Milky Way, the local injected spectrum can be harder. The time-dependent transport of particles would make the propagated spectrum even harder. Under this scenario, the anomalies of both primary (p, e − ) and secondary (e + ,p/p) cosmic rays can be properly interpreted. We further show that the TeV to sub-PeV anisotropy of proton is consistent with the observations if the local source is relatively young and lying at the anti-Galactic center direction.

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TeV cosmic-ray proton and helium spectra in the myriad model II

Cited by 12 publications

References 53 publications

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

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

The GALPROP Cosmic-ray Propagation and Non-thermal Emissions Framework: Release v57

Excesses of cosmic ray spectra from a single nearby source

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