Limits on the Isotropic Diffuse Flux of Ultrahigh Energy<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi></mml:math>Radiation

Chantell, M.; Covault, C. E.; Cronin, J. W.; Fick, B.; Fortson, L.; Fowler, J. W.; Green, K. D.; Newport, B. J.; Oser, S. M.; Catanese, M.; Glasmacher, M. A. K.; Matthews, J.; Nitz, D.; Sinclair, D.; Velde, J. C. van der; Kieda, D. B.

doi:10.1103/physrevlett.79.1805

Cited by 99 publications

(86 citation statements)

References 34 publications

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“…In this work, we used a refined sample of highquality data and obtained a value of the flux in excellent agreement with the result reported in [10]. The statistical significance of this result is reduced in accordance [14], detection claim), circle (Lodz [15], detection claim), triangles (EAS-TOP [16]), squares (CASA-MIA [17]), diamonds (KAS-CADE [18,19]); black open symbols -triangles (Yakutsk [20]), diamonds (Pierre Auger [21,22]), small squares (AGASA [23]), large squares (Telescope Array [24]). Systematic uncertainties (estimated for EAS-MSU but relevant for other data as well, see text) are shown by a double arrow.…”

supporting

confidence: 74%

Estimates of the cosmic gamma-ray flux at PeV to EeV energies from the EAS-MSU experiment data

et al. 2015

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Archival EAS-MSU data are searched for anomalous muonless events which may be caused by primary gamma rays with energies between 10 15 eV and 10 18 eV. We consider a refined sample of high-quality data and confirm the previously reported detection of a non-zero gamma-ray flux at ∼ 5 × 10 16 eV with a similar flux value but at somewhat lower statistical significance, corresponding to a depletion of the sample. We present upper limits on the flux below and above these energies, including the first constraints in the range 10 17 − 10 18 eV never studied by any other experiment.Searches for primary gamma rays in the extensive air shower (EAS) data have continued since 1960s (see e.g. Ref.[1] and, for a recent review, Ref.[2]) but started to attract a special attention after the recent announcement of the discovery of high-energy astrophysical neutrinos by the IceCube collaboration [3,4,5]. Indeed, in conventional scenarios, the high-energy neutrinos are produced in decays of charged pions, while accompanying neutral pions decay into photons (see e.g. Refs. [6,7,8,9] for more detailed discussions). Discovery of the neutrinos thus gives a hope to find the accompanying photons.One of the most elaborated methods to discriminate primary gamma rays is to search for air showers with low muon content because secondary muons are produced in hadronic interactions while the photon-induced EAS are mostly electromagnetic. A recent study of EAS-MSU events with estimated number of particles N e > 2 × 10 7 has revealed [10] an excess of muonless events compatible with non-zero primary gamma-ray flux at energies 50 PeV. The present work verifies the reported value of the flux with a refined sample of high-quality data and extends the N e range to demonstrate a coherent picture of the photon-flux measurements and upper limits in a wide energy band between ∼ 5 PeV and ∼ 500 PeV.The EAS-MSU experiment [11] and the analysis method [10] are described in detail in previous works. For the present study, events with the reconstructed number of particles N e > 10 6 and zenith angles θ < 30• , detected in 1982-1990, are selected. Muons with energies > 10 GeV were recorded by the central muon detector of 36.4 m 2 area. For air showers with N e > 10 7 , the triggering and selection systems have been described in 1) e-mail: st@ms2.inr.ac.ru Ref. [10]. At lower N e , the central selection system was used, based on a subset of 7 scintillator detectors; the central one, of 1 m 2 area, and 6 peripheric ones, each of 0.5 m 2 area, located at ∼ 60 m from the central one. The trigger corresponds to a simultaneous (within the time gate of 500 ns) firing of the central detector (with the threshold of 1 relativistic particle) and of at least two of peripheric ones (whose thresholds were set at the level of 1/3 of a relativistic particle). It is required that the 3 detectors do not lay on a straight line so that the determination of the EAS arrival direction is possible. The time resolution of the system is ∼ 5 ns, which determines the precision of ≤ 3• in...

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supporting

confidence: 74%

Estimates of the cosmic gamma-ray flux at PeV to EeV energies from the EAS-MSU experiment data

et al. 2015

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“…It was shown by Khristiansen et al (1975) that the fraction of photoninitiated showers in the data set obtained with the EAS MSU array in 1960s was of the order of 10 −3 . A similar estimate was obtained basing on the results of the CASA-MIA experiment, see Chantell et al 1997. Therefore, we have no ground to assume that the observed excess of CRs is formed due to photons.…”

Section: Discussionsupporting

confidence: 53%

Region of enhanced flux of cosmic rays with PeV energies toward the pulsars PSR J1840+5640 and LAT PSR J1836+5925

Zotov

Куликов

2010

Astron. Lett.

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An analysis of arrival directions of extensive air showers (EAS) registered with the EAS MSU and EAS-1000 prototype arrays has revealed a region of excessive flux of PeV cosmic rays in the direction toward pulsars PSR J1840+5640 and LAT PSR J1836+5925 at significance level up to 4.5σ. The first of the pulsars was discovered almost 30 years ago and is a well-studied old radio-pulsar located at the distance of 1.7 pc from the Solar system. The second pulsar belongs to a new type of pulsars, discovered by the space gamma-ray observatory Fermi, pulsations of which are not observed in optical and radio wavelengths but only in the gammaray range of energies (gamma-ray-only pulsars). In our opinion, the existence of the region of excessive flux of cosmic rays registered with two different arrays provides a strong evidence that isolated pulsars can give a noticeable contribution to the flux of Galactic cosmic rays in the PeV energy range.

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“…They are also presented in Fig. 3 and include upper limits from the EAS-TOP [24], KASCADE [26,27] and CASA-MIA [25] experiments at energies ∼ (0.1 − 30) PeV as well as recently published detection claims and upper limits from the EAS-MSU [28,29] experiment at ∼ (50 − 500) PeV. The main source of systematic errors for all these results is related to simulations of the background of photon-like hadronic events, subject to uncertainties of the hadronic interaction models used.…”

Section: Extragalactic Distribution: This Is Used For Illustrative Pumentioning

confidence: 99%

IceCube astrophysical neutrinos without a spectral cutoff and 1015–1017 eV cosmic gamma radiation

Kalashev

Troitsky²

2015

Jetp Lett.

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We present a range of unbroken power-law fits to the astrophysical-neutrino spectrum consistent with the most recent published IceCube data at the 68% confidence level. Assuming that the neutrinos originate in decays of pi mesons, we estimate accompanying gamma-ray fluxes for various distributions of sources, taking propagation effects into account. We then briefly discuss existing experimental results constraining PeV to EeV diffuse gamma-ray flux and their systematic uncertainties. Several scenarios are marginally consistent both with the KASKADE and CASA-MIA upper limits at (10 15 -10 16 ) eV and with the EAS-MSU tentative detection at ∼ 10 17 eV, given large systematic errors of the measurements. Future searches for the diffuse gamma-ray background at sub-PeV to sub-EeV energies just below present upper limits will give a crucial

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Limits on the Isotropic Diffuse Flux of Ultrahigh EnergyγRadiation

Cited by 99 publications

References 34 publications

Estimates of the cosmic gamma-ray flux at PeV to EeV energies from the EAS-MSU experiment data

Estimates of the cosmic gamma-ray flux at PeV to EeV energies from the EAS-MSU experiment data

Region of enhanced flux of cosmic rays with PeV energies toward the pulsars PSR J1840+5640 and LAT PSR J1836+5925

IceCube astrophysical neutrinos without a spectral cutoff and 1015–1017 eV cosmic gamma radiation

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