Search for astrophysical PeV gamma rays from point sources with Carpet-2

Abstract

Early results of the search for E γ > 1 PeV cosmic photons from point sources with the data of Carpet-2, an air-shower array equipped with a 175 m 2 muon detector, are presented. They include 95% CL upper limits on PeV photon fluxes from stacked directions of high-energy IceCube neutrino events and from four predefined sources, Crab, Cyg X-3, Mrk 421 and Mrk 501. An insignificant excess of events from Mrk 421 will be further monitored. Prospects of the use of the upgraded installation, Carpet-3 (410 m 2 muon detector), scheduled to start data taking in 2019, for searches of E γ > 100 TeV photons, are briefly

Carpet results on astrophysical gamma rays above 100 TeV

“…Preliminary results of the analysis above 1 PeV have been reported in Ref. [15] (see also Ref. [14] for PeV photons from the directions of IceCube events); here we refine these results and present also those for Dataset II of lower energies, see Table 1.…”

“…Interestingly, Mrk 421 demonstrates a weak, ∼ (2 − 3)σ , excess in both independent data sets (for Dataset I, this was pointed out in Ref. [15]). Gamma rays of the energies considered here should not arrive from extragalactic objects because of intense pair production on the cosmic microwave background [16].…”

“…Additional surface-detector stations will be installed to increase the collecting area. Preliminary simulations [15] allow to hope that one year of Carpet-3 live data taking might probe Galactic models of IceCube neutrinos [17] with the diffuse photon flux at E γ > 100 TeV.…”

Observation of photons above 300 TeV associated with a high-energy neutrino from the Cygnus region

“…The primary-particle energy is determined from the shower size N e , reconstructed from the central Carpet; the arrival direction is obtained from timing of the outer stations; the muon detector is used to select candidate gamma-ray showers which are muonpoor. The installation, its operation and data processing are described by Dzhappuev et al (2007); Szabelski et al (2009); Dzhappuev et al (2016);Troitsky et al (2019); Dzhappuev et al (2019a).…”

High-energy astrophysical neutrinos from interactions in the Local Bubble

“…3. Flux of gamma-rays at PeV energies can be measured by cosmic ray experimetns which have good hadron rejection factor, like CARPET-3 [19].…”