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      Spectra of cosmic ray electrons and diffuse gamma rays with the constraints of AMS-02 and HESS data

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          Abstract

          Recently, AMS-02 reported their observed results of cosmic rays(CRs). In addition to the AMS-02 data, we add HESS data to estimate the spectra of CR electrons and the diffuse gamma rays above TeV. In the conventional diffusion model, a global analysis is performed on the spectral features of CR electrons and the diffuse gamma rays by GALRPOP package. The results show that the spectrum structure of the primary component of CR electrons can not be fully reproduced by a simple power law and the relevant break is around hundred GeV. At 99\% C.L., the injection indices above the break decrease from 2.54 to 2.35, but the ones below the break are only in the range 2.746 - 2.751. The spectrum of CR electrons does not need to add TeV cutoff to match the features of HESS data too. Based on the difference between the fluxes of CR electrons and the primary component of them, the predicted excess of CR positrons is consistent with the interpretations as pulsar or dark matter. In the analysis of the Galactic diffuse gamma rays with the indirect constraint of AMS-02 and HESS data, it is found that the fluxes of Galactic diffuse gamma rays are consistent with GeV data of Fermi-LAT in the high latitude regions. The results indicate that the inverse Compton scattering(IC) is the dominant component in the range of the hundred GeV to tens of TeV respectively from the high latitude regions to the low ones, and in the all regions of Galaxy the flux of diffuse gamma rays is less than CR electrons at the energy scale of 20 TeV.

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          Most cited references9

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          Particle acceleration at astrophysical shocks: A theory of cosmic ray origin

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            GALPROP WebRun: an internet-based service for calculating galactic cosmic ray propagation and associated photon emissions

            , , (2011)
            GALPROP is a numerical code for calculating the galactic propagation of relativistic charged particles and the diffuse emissions produced during their propagation. The code incorporates as much realistic astrophysical input as possible together with latest theoretical developments and has become a de facto standard in astrophysics of cosmic rays. We present GALPROP WebRun, a service to the scientific community enabling easy use of the freely available GALPROP code via web browsers. In addition, we introduce the latest GALPROP version 54, available through this service.
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              Diffuse continuum gamma rays from the Galaxy

              A new study of the diffuse Galactic gamma-ray continuum radiation is presented, using a cosmic-ray propagation model which includes nucleons, antiprotons, electrons, positrons, and synchrotron radiation. Our treatment of the inverse Compton (IC) scattering includes the effect of anisotropic scattering in the Galactic interstellar radiation field (ISRF) and a new evaluation of the ISRF itself. Models based on locally measured electron and nucleon spectra and synchrotron constraints are consistent with gamma-ray measurements in the 30-500 MeV range, but outside this range excesses are apparent. A harder nucleon spectrum is considered but fitting to gamma rays causes it to violate limits from positrons and antiprotons. A harder interstellar electron spectrum allows the gamma-ray spectrum to be fitted above 1 GeV as well, and this can be further improved when combined with a modified nucleon spectrum which still respects the limits imposed by antiprotons and positrons. A large electron/IC halo is proposed which reproduces well the high-latitude variation of gamma-ray emission. The halo contribution of Galactic emission to the high-latitude gamma-ray intensity is large, with implications for the study of the diffuse extragalactic component and signatures of dark matter. The constraints provided by the radio synchrotron spectral index do not allow all of the <30 MeV gamma-ray emission to be explained in terms of a steep electron spectrum unless this takes the form of a sharp upturn below 200 MeV. This leads us to prefer a source population as the origin of the excess low-energy gamma rays.
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                Author and article information

                Journal
                2014-12-08
                2015-10-04
                Article
                10.1088/0004-637X/811/2/154
                1412.2499
                b463f38d-8e71-46f6-ab9f-a3308bc1ce21

                http://arxiv.org/licenses/nonexclusive-distrib/1.0/

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                Custom metadata
                Astrophys. J., vol. 811, no. 2, p. 154, Oct. 2015
                25 pages, 6 figures and 5 tables, revised version accepted for publication in APJ
                astro-ph.HE

                High energy astrophysical phenomena
                High energy astrophysical phenomena

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