In 2021, LHAASO observed a large number of Pevatrons in the Milky Way, which pointed out the direction for the sensitivity design of the next generation astronomy neutrino telescope, and it is expected to observe the precious neutrino celestial point source in the Milky Way only by designing a telescope with at least 30 times the sensitive volume of the IceCube detector. Therefore, we proposed...
The Electron-Thermal Neutron Detector Array (ENDA) is located at Haizishan, Daocheng, Sichuan Province, China, at an altitude of 4410 meters. The scientific goal of ENDA is to measure the composition-resolved energy spectrum of cosmic rays, particularly in the knee region, through joint observations with LHAASO. Currently, 64 detectors, so called ENDA-64, have been deployed at the LHAASO site...
The prototype of the ENDA (Electron Neutron Detector Array) cluster was created on the territory of the INR RAS in Moscow (ENDA-INR). The concept of the ENDA consists in simultaneous registration of the electromagnetic and thermal neutron components (being a part of hadronic component) of the EAS. The report is devoted to the first experimental data of the prototype together with the simulation data.
ENDA-INR is a sea level prototype of the running now at high altitude in China ENDA (Electron-Neutron Detector array), being a part of the LHAASO experiment. The main task of the ENDA is measuring of primary cosmic ray energy spectrum using hadronic EAS component. The latter is a principal point because only hadrons form the EAS “skeleton” which defined all its properties at observation level....
Recently, the Large High Altitude Air Shower Observatory (LHAASO) published measurements of the all-particle CR energy spectrum and the mean logarithmic mass of CRs with unprecedented accuracy in 0.3 - 30 PeV. The mean logarithmic mass shows a nonmonotonic change with energy, a feature observed for the first time.
Phenomenological studies of the cosmic-ray flux and its mass composition in...
In large-scale underwater neutrino telescopes, the geometry of the photomultiplier array constantly changes due to water currents, with individual optical modules drifting tens of meters from their initial positions. Accurate monitoring of the photomultiplier positions is indispensable to ensure stable telescope performance and maintain its angular resolution. In Baikal-GVD, the positioning of...
The muon component of extensive air showers (EAS) is widely used in the High-energy Physics as a tool for studying the processes of nucleus-nucleus interactions and secondary particle decays. Muons with energies above 100 TeV (very-high energy muons, VHE-muons) can provide information about new processes of muon generation. So the task of measuring the energy spectrum of such muons is...
Гравитационно-волновые детекторы LIGO, Virgo и KAGRA в настоящее время находятся в стадии 4-го наблюдательного периода (до октября 2025 г.). Информация о кандидатах в гравитационно-волновые события появляется на портале The General Coordinates Network (GCN). На Баксанском подземном сцинтилляционном телескопе (БПСТ) осуществляется своевременная сверка зарегистрированных мюонных нейтрино с...
It is shown that Eddington-like accretion event in the Galactic center several
million years ago and particle acceleration at accompanying shocks and jets could explain the the
observed cosmic ray spectrum at energies above 1 PeV. Cosmic ray particles are confined in extended
(several hundred kiloparsec in size) galactic halo. It is shown that the halo magnetic field could be as small...
Galactic cosmic rays up to about 100 PeV are believed to be accelerated by shock waves at supernova remnants by a Fermi process called diffusive shock acceleration (DSA). In this process, a test particle undergo a number of encounters with both inhomogeneities in the interstellar space and with shock and gain an energy.
All collisionless shock calculations should approximate particle...
Young compact clusters of massive stars contain dozens of O-, B and WR-type stars with fast powerful winds in a small ∼ pc radius. The particle acceleration by ensembles of shocks and waves of compression and rarefaction in the turbulent environment of young massive star clusters (YMSCs) is an alternative to the standard paradigm of Galactic cosmic rays acceleration on supernova shocks. In...
Based on direct numerical modeling, it is shown that pulsar wind nebulae (PWN) with a double X-ray torus are capable of accelerating very high energy protons. These objects (with well known Vela nebula as the prototype) are distinguished by a special structure of MHD flows of strongly magnetized plasma. This special structure of the nebula allows for longtime confinement of high-energy...
The GRAPES-3 experiment, located in Ooty, India, uses an array of 400 plastic scintillator detectors deployed over 25,000 m^2, and a 560 m^2 tracking muon telescope to record extensive air showers in the TeV–PeV energy range and angular muon flux above a GeV, respectively. The energy spectrum and nuclear mass composition of primary cosmic rays, solar and heliospheric phenomena, and...
Одной из основных задач исследования гамма источников с помощью атмосферных черенковских телескопов (АЧТ) является восстановление энергетического спектра испускаемых гамма квантов. В традиционном методе определения энергии гамма квантов физические характеристики восстанавливаются путем анализа параметров Хилласа, полученных из изображений ШАЛ на АЧТ и которые являются следствием статистических...
A new simulation using the CORSIKA code without accelerating coarsening of the results was performed for the energy range of 1-100 PeV, taking into account pulse formation at the input of the optical station of the TAIGA-HiSCORE array. Refined relationships between the steepness parameter of the lateral distribution function (LDF) and the light pulse FWHM at distances of 200-400 m and the...
В статье развивается метод поиска гамма- излучения от неизвестных источников над сложным астрофизическом фоном по данным установки HiSCORE в эксперименте TAIGA. Такая задача распадается на три этапа: разработка критериев выделения гамма-квантов от частиц, составляющих основной фон; выбор метода оценки и сглаживание фона; анализ статистической значимости сигнала на...
The main information about high-energy cosmic rays (above 10^15 eV) is provided by the extensive air showers (EAS), which are formed as a result of interaction of primary cosmic rays (PCR) with nuclei of atmospheric atoms. In the energy range from 10^15 to 10^17 eV, the PCR energy spectrum reconstructed by the data of EAS experiments has features which cannot be explained within the frameworks...
Recent experimental results have shown an excess of muons in extensive air showers produced by cosmic rays with energies above $10^{17}$ eV. In this work, I discuss how even small deviations from Lorentz-invariant physics could influence the interpretation of the current state of the so-called "muon puzzle."
One of the intriguing possibilities in the search for the new physics in ultra-high energy cosmic rays (UHECR) is the discovery of the Lorentz invariance violation (LIV). Several studies have investigated the consequences of the different LIV scenarios for cosmic ray physics and their influence on the measured properties of the extensive air showers (EAS). Yet, only recently, a new approach...
The TAIGA-HiSCORE EAS Cherenkov light array with total area of about 1 km^2 has collected data during the 3 seasons of observation (2021 – 2024). Reconstruction of the primary energy with Cherenkov light fluxes at the distances 100 and 200 m from the core with the adequate zenith angle corrections let us obtain the energy spectrum in the range from 300 TeV to 10 PeV. Our spectrum is in...
We present the results of a study on the mass composition of cosmic rays (CRs) in individual air shower events with energies of 0.8–2 EeV and arrival zenith angles less than 60°. The analysis utilizes extensive air showers (EAS) recorded over three observation seasons (2021–2024) by the Yakutsk EAS array following its major upgrade in 2019–2021. The CR composition was estimated by comparing...
The results of the analysis of the NEVOD-DECOR data on the study of inclined muon bundles of cosmic rays for the period from 2012 to 2023 are presented. An original method for studying the muon component of extensive air showers, local muon density spectra, was used. The data are compared with the calculations based on the simulation of air showers using the CORSIKA program for different...
The Horizont-T installation at the Tian Shan High-Mountain Scientific Station of the Lebedev Physical Institute (LPI/FIAN), located at an altitude of 3350 meters above sea level, is designed for the detection of extensive air showers (EAS) of ultra-high energies with axis inclinations up to 70$^o$. The capabilities of the equipment allow for digitization of signals recorded by scintillation...
The SPHERE-3 setup is destined to register the EAS Cherenkov light, both the direct and the reflected from the snow surface. A set of methods and new approaches in the measurement technique enable substantial progress in the study of the primary cosmic ray composition in the energy range 1-1000 PeV. The present work reveals the current status of the project development and detector performance...
New results of modelling the operation of the new Cherenkov telescope SPHERE-3 are presented. The telescope will be able to detect cosmic particles by direct and reflected Cherenkov light of EAS. Dual detection improves the accuracy of determining the parameters of the primary particle. The study is based on the data bank of distributions of the EAS Cherenkov light obtained on the Lomonosov-2...
The source of the remarkable ultra high energy neutrino event KM3-230213A detected with the KM3-ARCA array is still not established. A persistent isotropic source hypothesis is disfavored due to the non-observation of a similar event by the larger IceCube detector that benefits from $\sim$ an order-of-magnitude larger observation time compared to the KM3-ARCA array as well.
We consider two...
We discuss the constraints on superluminal neutrino Lorentz Invariance Violation (LIV) parameters from the observation of the ultra-high-energy event KM3-230213A by the KM3NeT collaboration in cases of linear n=1 and quadratic n=2 LIV scenarios. Assuming extragalactic origin of the event, we obtain the constraints on LIV mass scale Λ_1=1.1×10^30 GeV and Λ_2=1.1×1019 GeV from the absence...
The idea that supernova remnants are a significant source of Galactic cosmic rays is supported by the fact that HESS J1731-347 would be one of the few Galactic sources to accelerate hadronic cosmic rays to TeV energy. The radius (4.2-5.5 km) and estimated mass (~ 0.77 $M_☉$) are both much less than the usual range for neutron stars. Because of its compactness and short radius, we investigate a...
An excess of extensive air showers (EAS) muons was found in several experiments at energies above 10^17 eV compared to estimates assuming even heavy composition of primary cosmic rays (PCR). Presently, the explanations for this excess are being explored, including both the potentially new physical phenomena and states of matter in EAS development, along with the efforts to modify existing...
This report presents a draft of a new detector designed to determine the chemical composition of primary cosmic rays based on the characteristics of the angular distribution of Cherenkov light from EAS. The installation, consisting of several such detectors, will be able to register individual EAS events in the energy range from 1 to 1000 PeV with high angular resolution of up to 0.3 degrees....
The origin of antiparticles -- positrons and antiprotons -- as detected by the observatories PAMELA and AMS-02 is a topical issue due to their discussed relation to the dark matter annihilations/decays. On the other hand, the observed excess of positrons can be explained by a contribution from the near-Earth pulsars once these are driving a bow shock into the interstellar medium. In this case...
The paper presents the first results of the search for ultra-high-energy gamma radiation from cosmic gamma-ray bursts based on the data from the Carpet-3 EAS array of the BNO INR RAS. The facility is located in the Baksan gorge at an altitude of 1700 m above sea level and consists of a ground-based array of and an underground muon detector with an area of 410 sq. m., which allows for the...
The brightest cosmic gamma-ray burst (GRB) ever detected, GRB~221009A, was accompanied by photons of very high energies. These gamma rays may be used to test both the astrophysical models of the burst and our understanding of long-distance propagation of energetic photons, including potential new-physics effects. Here we present the observation of a photon-like air shower with the estimated...
In the extensive air showers (EASs), photonuclear reactions transfer energy from the electromagnetic to the hadronic cascade and thus contribute to the muon production rate. However, the high-energy (center-of-momentum frame energy > 100 GeV) photonuclear cross-section is poorly constrained by laboratory experiments. This implies a systematic uncertainty in the Monte-Carlo (MC) simulations of...
The mean depth of shower is used for studying interconnection between shower longitudinal profile and hadronic interaction characteristics. The equations for the shower originated by high energy proton in the atmosphere are written and, within certain simplifications, solved for the case of logarithmically decreasing interaction length of hadrons in air.
The obtained expression explicitely...
The problem of the excess of muons in extensive air showers (EAS) from ultra-high energy cosmic rays (UHECR) in comparison to the simulation predictions, also known as the “muon puzzle”, stands as a bright signal of the incompleteness of our knowledge of high-energy cosmic ray physics. In principle, there are several ways to explain this phenomenon. One can suggest changes in the cosmic ray...
