Deriving the cosmic ray spectrum from gamma-ray observations

Kachelrieß, M.; Ostapchenko, S.

doi:10.1103/physrevd.86.043004

Cited by 55 publications

(69 citation statements)

References 40 publications

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“…For the spectrum of secondary photons and neutrinos produced in pp interactions differential cross sections tabulated from QGSJET-II-04 were used [31]. Secondaries from heavier elements in the CR flux are suppressed.…”

Section: B Cr Interactions With Gas and Photonsmentioning

confidence: 99%

Unified model for cosmic rays above1017 eVand the diffuse gamma-ray and neutrino backgrounds

et al. 2015

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We investigate how the extragalactic proton component derived within the "escape model" can be explained by astrophysical sources. We consider as possible cosmic ray (CR) sources normal/starburst galaxies and radio-loud active galactic nuclei (AGN). We find that the contribution to the total extragalactic proton flux from normal and starburst galaxies is only subdominant and does not fit the spectral shape deduced in the escape model. In the case of radio-loud AGN, we show that the complete extragalactic proton spectrum can be explained by a single source population, BL Lac/FR I, for any of the potential acceleration sites in these sources. We calculate the diffuse neutrino and γ-ray fluxes produced by these CR protons interacting with gas inside their sources. For a spectral slope of CRs close to α = 2.1 − 2.2 as suggested by shock acceleration, we find that these UHECR sources contribute the dominant fraction of both the isotropic γ-ray background and of the extragalactic part of the astrophysical neutrino signal observed by IceCube.

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Section: B Cr Interactions With Gas and Photonsmentioning

confidence: 99%

Unified model for cosmic rays above1017 eVand the diffuse gamma-ray and neutrino backgrounds

et al. 2015

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“…In our work, we simplify the hadron collisions between CRs and target atoms (e.g., in the MC) to proton-proton (pp) collisions only. The cross-section table of the pp collision was obtained from Kachelrieß & Ostapchenko (2012).…”

Section: The Nearby Molecular Cloudsmentioning

confidence: 99%

A young supernova remnant illuminating nearby molecular clouds with cosmic rays

Cui

Pühlhofer

Santangelo

2016

A&A

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The supernova remnant (SNR) HESS J1731-347 displays strong nonthermal TeV γ-ray and X-ray emission, thus the object is presently accelerating particles to very high energies. A distinctive feature of this young SNR is the nearby (∼30 pc in projection) extended source HESS J1729-345, which is currently unidentified but is in spatial projection coinciding with known molecular clouds (MC). We model the SNR evolution to explore whether the TeV emission from HESS J1729-345 can be explained as emission from runaway hadronic cosmic rays (CRs) that are illuminating these MCs. The observational data of HESS J1729-345 and HESS J1731-347 can be reproduced using core-collapse SN models for HESS J1731-347. Starting with different progenitor stars and their presupernova environment, we model potential SNR evolution histories along with the CR acceleration in the SNR and the diffusion of the CRs. A simplified three-dimensional structure of the MCs is introduced based on 12 CO data of that region, adopting a distance of 3.2 kpc to the source. A Monte Carlo based diffusion model for the escaping CRs is developed to deal with the inhomogeneous environment. The fast SNR forward shock speed, as implied from the X-ray data, can easily be explained when employing scenarios with progenitor star masses between 20 M and 25 M , where the SNR shock is still expanding inside the main-sequence (MS) bubble at present time. The TeV spectrum of HESS J1729-345 is satisfactorily fitted by the emission from the highest energy CRs that have escaped the SNR, using a standard Galactic CR diffusion coefficient in the interclump medium. The TeV image of HESS J1729-345 can be explained with a reasonable three-dimensional structure of MCs. The TeV emission from the SNR itself is dominated by leptonic emission in this model. We also explore scenarios where the shock is starting to encounter the dense MS progenitor wind bubble shell. The escaping hadronic CR hypothesis for the γ-ray emission of HESS J1729-345 can still hold, but even in this case our model cannot easily account for the TeV emission from HESS J1731-347 in a hadronic scenario.

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“…3 we replace the χ 2 analysis by a Markov chain Monte Carlo (MCMC) exploration of the parameter space to obtain the credible intervals (CIs) and correlations between IS flux and modulation parameters. We also compare our results to the recent low-energy Voyager data, which are considered to be a direct probe of the local IS fluxes (Stone et al 2013;Webber & Higbie 2013;Webber et al 2013a,b), and to the indirect observation of IS fluxes in the direction of molecular complexes from Fermi-LAT γ-ray data (Neronov et al 2012;Kachelrieß & Ostapchenko 2012;Yang et al 2014;Strong 2015), before concluding in Sect. 4.…”

Section: Introductionmentioning

confidence: 88%

Non-parametric determination of H and He interstellar fluxes from cosmic-ray data

Ghelfi

Barão

Derome

et al. 2016

A&A

107

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Context. Top-of-atmosphere (TOA) cosmic-ray (CR) fluxes from satellites and balloon-borne experiments are snapshots of the solar activity imprinted on the interstellar (IS) fluxes. Given a series of snapshots, the unknown IS flux shape and the level of modulation (for each snapshot) can be recovered. Aims. We wish (i) to provide the most accurate determination of the IS H and He fluxes from TOA data alone; (ii) to obtain the associated modulation levels (and uncertainties) while fully accounting for the correlations with the IS flux uncertainties; and (iii) to inspect whether the minimal force-field approximation is sufficient to explain all the data at hand. Methods. Using H and He TOA measurements, including the recent high-precision AMS, BESS-Polar, and PAMELA data, we performed a non-parametric fit of the IS fluxes J IS H, He and modulation level φ i for each data-taking period. We relied on a Markov chain Monte Carlo (MCMC) engine to extract the probability density function and correlations (hence the credible intervals) of the sought parameters. Results. Although H and He are the most abundant and best measured CR species, several datasets had to be excluded from the analysis because of inconsistencies with other measurements. From the subset of data passing our consistency cut, we provide readyto-use best-fit and credible intervals for the H and He IS fluxes from MeV/n to PeV/n energy (with a relative precision in the range [2−10%] at 1σ). Given the strong correlation between J IS and φ i parameters, the uncertainties on J IS translate into ∆φ ≈ ±30 MV (at 1σ) for all experiments. We also find that the presence of 3 He in He data biases φ towards higher φ values by ∼30 MV. The force-field approximation, despite its limitation, gives an excellent (χ 2 /d.o.f. = 1.02) description of the recent high-precision TOA H and He fluxes. Conclusions. The analysis must be extended to different charge species and more realistic modulation models. It would benefit from the AMS-02 unique capability of providing frequent high-precision snapshots of the TOA fluxes over a full solar cycle.

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Deriving the cosmic ray spectrum from gamma-ray observations

Cited by 55 publications

References 40 publications

Unified model for cosmic rays above1017 eVand the diffuse gamma-ray and neutrino backgrounds

Unified model for cosmic rays above1017 eVand the diffuse gamma-ray and neutrino backgrounds

A young supernova remnant illuminating nearby molecular clouds with cosmic rays

Non-parametric determination of H and He interstellar fluxes from cosmic-ray data

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