An excess of cosmic ray electrons at energies of 300–800 GeV

Chang, Jin; Adams, J. H.; Ahn, H. S.; Bashindzhagyan, G. L.; Christl, M. J.; Ganel, O.; Guzik, T. G.; Isbert, J.; Kim, K. C.; Kuznetsov, E.; Panasyuk, M. I.; Панов, А. Д.; Schmidt, Wolfgang; Seo, E. S.; Sokolskaya, N. V.; Watts, J. W.; Wefel, J. P.; Wu, Jian; Zatsepin, V. I.

doi:10.1038/nature07477

Cited by 954 publications

(938 citation statements)

References 27 publications

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“…Electrons produced in local SNRs are expected to fill out the electron spectrum above 100 GeV. In this picture the fraction of positrons in the cosmic ray lepton spectrum should decrease with increasing energy, in contradiction to results from ATIC [6] [4], which show that the positron fraction in fact increases with energy. While this effect could be produced by WIMP dark matter annihilation, the anomalous positron fraction can also be explained by nearby astrophysical sources, most notably pulsars and PWNe.…”

Section: Pulsar Wind Nebulae and The Positron Excesscontrasting

confidence: 42%

“…The Fermi Gamma-ray Space Telescope (Fermi LAT) can map the entire gamma-ray sky between 300 MeV and 500 GeV over all spatial scales, with an angular resolution that ranges from 0.1 • to 1 • depending Figure 1: Comparison to extant data from AMS-02 [4], Fermi LAT [5], ATIC [6], HEAT [7], CAPRICE [8], BETS [9], and H.E.S.S. [10] of a model considering contributions to the e ± flux from the following categories: e − from distant (> 3 kpc) SNRs (dot-dashed yellow) and local SNRs (dotted green), secondary e ± (long dashed red) and e ± from PWNe (short dashed blue).…”

Section: Dramatis Personaementioning

confidence: 99%

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Pulsar Wind Nebulae and Cosmic Rays: A Bedtime Story

Weinstein¹

2014

Nuclear Physics B - Proceedings Supplements

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The role pulsar wind nebulae play in producing our locally observed cosmic ray spectrum remains murky, yet intriguing. Pulsar wind nebulae are born and evolve in conjunction with SNRs, which are favored sites of Galactic cosmic ray acceleration. As a result they frequently complicate interpretation of the gamma-ray emission seen from SNRs. However, pulsar wind nebulae may also contribute directly to the local cosmic ray spectrum, particularly the leptonic component. This paper reviews the current thinking on pulsar wind nebulae and their connection to cosmic ray production from an observational perspective. It also considers how both future technologies and new ways of analyzing existing data can help us to better address the relevant theoretical questions. A number of key points will be illustrated with recent results from the VHE (E > 100 GeV) gamma-ray observatory VERITAS. Keywords: IntroductionThe discovery of cosmic rays in the early twentieth century [1, 2] inaugurated a decades-long, serialized mystery story that has yet to be completed. At the heart of the mystery lies a set of of simple questions. What particles appear in the cosmic ray spectrum that we see from Earth? Where do these particles originate? How are they accelerated? In recent decades direct cosmic ray observations have brought us a wealth of information on the cosmic ray spectrum and its composition, clues to the types of environments in which cosmic rays are born. The interaction of these particles with interstellar magnetic fields, however, prevents them from being traced back to their point of origin.In order to pursue the other half of this mystery-the nature of cosmic ray accelerators-we must use the secondary photon radiation produced in these cosmic ray nurseries. These high-energy (300 MeV -100 GeV) and very high-energy (VHE; E > 100 GeV) gamma rays are not deflected by interstellar magnetic fields and can be used to map cosmic ray populations in and near their parent accelerators. The different processes by which relativistic cosmic ray electrons, protons, and heavier nuclei produce high-energy gamma rays leave characteristic imprints on the gamma-ray energy spectrum of particular astrophysical accelerators. These features may be used to constrain the composition and energy spectrum of accelerated particle populations.The local cosmic ray spectrum is known to be a mix of protons and heavier nuclei, with a smaller admixture of leptons. A mix of astrophysical accelerators within and outside our Galaxy is believed to contribute, including shocks arising in supernova remnants (SNRs), shocks formed by interacting high-velocity winds from massive stars [3], pulsars, and active galactic nuclei (AGN). We focus here on a single subplot of a much larger story-the role played by pulsar wind nebulae (PWNe) in our quest to understand the Galactic cosmic ray spectrum. Dramatis PersonaeNo single gamma-ray observatory provides a complete picture of the gamma-ray sky at all energies and spatial scales. The Fermi Gamma-ray Space Telescope (...

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Section: Pulsar Wind Nebulae and The Positron Excesscontrasting

confidence: 42%

Section: Dramatis Personaementioning

confidence: 99%

Pulsar Wind Nebulae and Cosmic Rays: A Bedtime Story

Weinstein¹

2014

Nuclear Physics B - Proceedings Supplements

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“…One way to detect WIMPs is to search for its annihilation/decay products, which may lead to characteristic features in the observed spectra of cosmic electrons (plus positron) or gamma-ray spectra. Some circumstantial evidence or hints of anomalies have been reported [2,3,4]; however, astrophysical sources like pulsars and pulsar wind nebulae can also contribute to these results. Future more precise measurements at higher energies are still needed.…”

Section: Introductionmentioning

confidence: 99%

Introduction to the High Energy cosmic-Radiation Detection (HERD) Facility onboard China’s Future Space Station

Zhang¹,

Adriani²,

Albergo³

et al. 2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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PoS(ICRC2017)1077The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads onboard China's Space Station, which is planned for operation starting around 2025 for about 10 years. The main scientific objectives of HERD are searching for signals of dark matter annihilation products, precise cosmic electron (plus positron) spectrum and anisotropy measurements up to 10 TeV, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray monitoring and survey. HERD is composed of a 3-D cubic calorimeter (CALO) surrounded by microstrip silicon trackers (STKs) from five sides except the bottom. CALO is made of about 7,500 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. The top STK microstrips of six X-Y layers are sandwiched with tungsten converters to make precise directional measurements of incoming electrons and gamma-rays. In the baseline design, each of the four side STKs is made of only three layers microstrips. All STKs will also be used for measuring the charge and incoming directions of cosmic rays, as well as identifying back scattered tracks. With this design, HERD can achieve the following performance: energy resolution of 1% for electrons and gamma-rays beyond 100 GeV and 20% for protons from 100 GeV to 1 PeV; electron/proton separation power better than 10 −5 ; effective geometrical factors of >3 m 2 sr for electron and diffuse gamma-rays, >2 m 2 sr for cosmic ray nuclei. R&D is under way for reading out the LYSO signals with optical fiber coupled to image intensified IsCMOS and CALO prototype of 250 LYSO crystals.

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“…Recently, observations of the cosmic ray (CR) positron fraction by the PAMELA experiment [1], the total electron and positron spectra by the ATIC [2] experiment, the PPB-BETS [3] experiment, the HESS [4,5] experiment and the Fermi [6] experiment all show interesting excesses when compared with the expectations of the conventional astrophysical background.…”

Section: Introductionmentioning

confidence: 99%