Search for dark matter by the Yakutsk array data

We analyzed the Yakutsk Extensive Air Shower array data registered from 1974 to 2011. 14 particles were found that come directly from the Galactic Center to Earth without any deflection in the Galactic magnetic field.We suppose that these are particles of dark matter.


Introduction
We analyzed the distribution of particles detected by the Yakutsk array for energies E ≥ 8.10 18 eV from 1974 until 2011.We considered the arrival directions of extensive air showers (EAS) with zenith angles θ < 60 • and whose cores were situated inside the perimeter of the array.The energy of the particles was determined by registering Cherenkov light with an accuracy of ∼30% and for angles ∼ 5 • − 7 • .

The distribution of particles in right ascension
At first we analyzed the distribution of particles in right ascension by harmonic analyses for energies E ≥ 8.10 18 eV.For these energies we found the amplitude and phase in right ascension of the 1 st harmonic of Fourier analysis to be r 1 = 0.14 ± 0.04, φ 1 = 0.6 • ± 19 • , r 2 = 0.02 ± 0.04, φ 2 = 8 • ± 125 • .The total number of particles detected was 938 and the chance probability, P, having amplitudes r 1 ≥ 0.14 is ∼0.01.
Earlier we suggested a new method to analyze data only along two coordinates, declination and right ascension, and we analysed the data by this method [1].We did not find any statistical significance in the amplitude of arrival directions of particles by Fourier analyses, but phases of the 1 st harmonic at energies E > 10 19 eV start to change at right ascension RA∼ 180 • or at high galactic latitudes, b (Fig. 1).Possibly this change of phase of the 1 st harmonic most likely points to a change of sources of ultrahigh energy cosmic rays to high latitudes.
Note that the chance probabilities are only significant around the 1 st and 3 rd groups of pulsars at radius R < 6 • and are 3σ more than expected in the case of isotropy.The maximum number of events 20 ≤ n ≤ 23 at R < 6 • are observed around the 1 st groups of pulsars: PSR 0141+6009, 0146+6145, 0147+5922, 0157+6212, 0215+6218.These pulsars are in the galactic plane and have been considered earlier as possible sources of particles [1].
A flux of particles was observed from the side center of the Galaxy (Fig. 1, number 3).All 14 particles arrive at the Yakutsk array at large zenith angles, 60 • ≥ θ ≥ 38 • , and from only one direction as neutral particles of dark matter (the trajectories of these particles are not similar to other particles arriving directly from one direction only -the Galactic Center without any deviation).From 6 showers we have no information about the muon component data -these showers were registered in the summer (in summer muon detectors do not operate ISVHECRI 2016 because they are underground in permafrost and possible melting permafrost).In the autumn after repair the muon detectors begin to operate.Note that an excess of particles was found from the direction of the Galactic center mainly in autumn at energy E ∼ 10 18 eV (according to theory maximum fluxes of particles of dark matter are expected in autumn [2]).We suppose that we registered particles of dark matter.The AGASA and Sydney arrays also observed a flux of particles from the same direction -the side center of the Galaxy [3,4].

Conclusion
We have found correlations between the arrival directions of ultrahigh energy particles with E < 4 × 10 19 eV and the positions of pulsars and an anisotropy of the arrival directions of these particles from the side of the galactic plane for both the Yakutsk array data and the Telescope Array data at energy E > 5.7 × 10 19 eV at high galactic latitudes.0ur analysis of the data shows that the cosmic rays observed up to 4 × 10 19 eV are galactic and above this energy most likely extragalactic.