Hadronic Cosmic Rays Research Articles

Early-timeγ-ray constraints on cosmic-ray acceleration in the core-collapse SN 2023ixf with theFermiLarge Area Telescope

Context.While supernova remnants (SNRs) have been considered the most relevant Galactic cosmic ray (CR) accelerators for decades, core-collapse supernovae (CCSNe) could accelerate particles during the earliest stages of their evolution and hence contribute to the CR energy budget in the Galaxy. Some SNRs have indeed been associated with TeVγ-rays, yet proton acceleration efficiency during the early stages of an SN expansion remains mostly unconstrained.Aims.The multi-wavelength observation of SN 2023ixf, a Type II supernova (SN) in the nearby galaxy M 101 (at a distance of 6.85 Mpc), opens the possibility to constrain CR acceleration within a few days after the collapse of the red super-giant stellar progenitor. With this work, we intend to provide a phenomenological, quasi-model-independent constraint on the CR acceleration efficiency during this event at photon energies above 100 MeV.Methods.We performed a maximum-likelihood analysis ofγ-ray data from theFermiLarge Area Telescope up to one month after the SN explosion. We searched for high-energy, non-thermal emission from its expanding shock, and estimated the underlying hadronic CR energy reservoir assuming a power-law proton distribution consistent with standard diffusive shock acceleration.Results.We do not find significantγ-ray emission from SN 2023ixf. Nonetheless, our non-detection provides the first limit on the energy transferred to the population of hadronic CRs during the very early expansion of a CCSN.Conclusions.Under reasonable assumptions, our limits would imply a maximum efficiency on the CR acceleration of as low as 1%, which is inconsistent with the common estimate of 10% in generic SNe. However, this result is highly dependent on the assumed geometry of the circumstellar medium, and could be relaxed back to 10% by challenging spherical symmetry. Consequently, a more sophisticated, inhomogeneous characterisation of the shock and the progenitor’s environment is required before establishing whether or not Type II SNe are indeed efficient CR accelerators at early times.

Neural networks for separation of cosmic gamma rays and hadronic cosmic rays in air shower observation with a large area surface detector array

The Tibet ASγ experiment has been observing cosmic gamma rays and cosmic rays in the energy range from teraelectron volts to several tens of petaelectron volts with a surface detector array since 1990. The derivation of cosmic gamma-ray flux is made by finding the excess distribution of the arrival direction of air showers above background cosmic rays. In 2014, the underground water Cherenkov muon detector (MD) was added to separate cosmic gamma rays from the background on the basis of the muon-less feature of the air showers of gamma-ray origin; hybrid observations using these two detectors were started at this time. In the present study, we developed methods to separate gamma-ray-induced air showers and hadronic cosmic-ray-induced ones using the measured particle number density distribution to improve the sensitivity of cosmic gamma-ray measurements using the Tibet air shower array data alone before the installation of the MD. We tested two approaches based on neural networks. The first method used feature values representing the lateral spread of the secondary particles, and the second method used the shower image data. To compare the separation performance of each method, we analyzed Monte Carlo air shower events in the vertically incident direction with mono-initial-energy gamma rays and protons. When discriminated by a single feature, the feature with the highest separation performance has an area under the curve (AUC) value of 0.701 for a gamma-ray energy of 10 TeV and 0.808 for 100 TeV. A separation method with a multilayer perceptron (MLP) based on multiple features has AUC values of 0.761 for a gamma-ray energy of 10 TeV and 0.854 for 100 TeV, which represents an improvement of approximately 5% in the AUC value compared with the single-feature case. We also found that the feature values that effectively contribute to the separation vary depending on the energy. A separation method with a convolutional neural network (CNN) using the shower image data has AUC values of 0.781 for a gamma-ray energy of 10 TeV and 0.901 for 100 TeV, which are approximately 5% higher than those of the MLP method. We applied the CNN separation method to Monte Carlo gamma-ray and cosmic-ray events from the Crab Nebula in the energy range 10–100 TeV. The AUC values range from 0.753 to 0.879, and the significance of the observed gamma-ray excess is improved by 1.3 to 1.8 times compared with the case without the separation procedure.

CONGRuENTS (COsmic-ray, Neutrino, Gamma-ray and Radio Non-Thermal Spectra) – II. Population-level correlations between galactic infrared, radio, and γ-ray emission

ABSTRACT Galaxies obey a number of empirical correlations between their radio, γ-ray, and infrared emission, but the physical origins of these correlations remain uncertain. Here, we use the CONGRuENTS model for broad-band non-thermal emission from star-forming galaxies, which self-consistently calculates energy-dependent transport and non-thermal emission from cosmic ray hadrons and leptons, to predict radio and γ-ray emission for a synthetic galaxy population with properties drawn from a large deep-field survey. We show that our synthetic galaxies reproduce observed relations such as the far infrared (FIR)–radio correlation, the FIR–γ correlation, and the distribution of radio spectral indices, and we use the model to explain the physical origins of these relations. Our results show that the FIR–radio correlation arises because the amount of cosmic ray electron power ultimately radiated as synchrotron emission varies only weakly with galaxy star formation rate as a result of the constraints imposed on gas properties by hydrostatic balance and turbulent dynamo action; the same physics dictates the extent of proton calorimetry in different galaxies, and thus sets the FIR–γ–ray correlation. We further show that galactic radio spectral indices result primarily from competition between thermal free–free emission and energy-dependent loss of cosmic ray electrons to bremsstrahlung and escape into galactic haloes, with shaping of the spectrum by inverse Compton, synchrotron, and ionization processes typically playing a subdominant role. In addition to explaining existing observations, we use our analysis to predict a heretofore unseen correlation between the curvature of galaxies’ radio spectra and their pion-driven γ-ray emission, a prediction that will be testable with upcoming facilities.

Particle acceleration test with Cas A multiwavelength emission

AbstractThe investigation of supernova remnants (SNRs) across the electromagnetic spectrum from radio up to very high energy gamma‐rays can serve as a test of the particle acceleration and touches on one of the unresolved problems of modern astrophysics, namely the origin of cosmic rays and the Galaxy's contribution to the overall cosmic ray spectrum. The multiwavelength observations of Cas A SNR demonstrated that structure and spectral features have clear signs of young SNRs and its overall properties make this object the best target to test a hypothesis of cosmic ray origin in SNRs. Studies of Cas A at very high energies by SHALON telescope showed the location of TeV gamma‐ray emission region relative to the position of reveres shock. Also, the spectral energy distribution was obtained at high and very high energies. To describe the spectral and structural features of this SNR viewed in non‐thermal emission, two approaches involving reverse and also both reverse and forward shocks to the mechanism of diffusive shock acceleration of cosmic rays in Cas A were applied. It is demonstrated that the observational properties of Cas A are well reproduced by the hadronic model with significant contribution of both the forward and reverse shocks in the generation of broadband emission. Calculation results suggest that the very high efficiency of particle acceleration in Cas A, which value is up to 25% of the supernova explosion energy with energy of accelerated particles not exceeding of eV. Whereas, the forward shock model predicts the spectral characteristics of the TeV‐gamma‐emission corresponding to ones detected at 800 GeV–40 TeV that are the evidence of acceleration of the hadronic cosmic rays in shells of SNRs up to eV

Leptonic Model for Neutrino Emission from Active Galactic Nuclei.

It is often stated that the observation of high-energy neutrinos from an astrophysical source would constitute indisputable proof for the acceleration of hadronic cosmic rays. Here, we point out that there exists a purely leptonic mechanism to produce TeV-scale neutrinos in astrophysical environments. In particular, very high-energy synchrotron photons can scatter with x rays, exceeding the threshold for muon-antimuon pair production. When these muons decay, they produce neutrinos without any cosmic-ray protons or nuclei being involved. In order for this mechanism to be efficient, the source in question must produce very high-energy photons which interact in an environment that is dominated by keV-scale radiation. We find that such a source could potentially generate an observable neutrino flux through muon pair production for reasonable choices of physical parameters.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10TeV to 1PeV with LHAASO-KM2A.

The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the MilkyWay. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10TeV and 1PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°<l<125°, |b|<5°) and outer (125°<l<235°, |b|<5°) Galactic plane are detected with 29.1σ and 12.7σ significance, respectively. The outer Galactic plane diffuse emission is detected for the first time in the very- to ultra-high-energy domain (E>10 TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60 TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

Search for Extended Sources of Neutrino Emission in the Galactic Plane with IceCube

The Galactic plane, harboring a diffuse neutrino flux, is a particularly interesting target in which to study potential cosmic-ray acceleration sites. Recent gamma-ray observations by HAWC and LHAASO have presented evidence for multiple Galactic sources that exhibit a spatially extended morphology and have energy spectra continuing beyond 100 TeV. A fraction of such emission could be produced by interactions of accelerated hadronic cosmic rays, resulting in an excess of high-energy neutrinos clustered near these regions. Using 10 years of IceCube data comprising track-like events that originate from charged-current muon neutrino interactions, we perform a dedicated search for extended neutrino sources in the Galaxy. We find no evidence for time-integrated neutrino emission from the potential extended sources studied in the Galactic plane. The most significant location, at 2.6σ post-trials, is a 1.°7 sized region coincident with the unidentified TeV gamma-ray source 3HWC J1951+266. We provide strong constraints on hadronic emission from several regions in the galaxy.

Tachyonic Neutrinos: From the Cosmic Rays to Extragalactic Supernovae

The possibility of neutrinos moving at faster-than-light speeds can be modeled using terms in the Lagrangian that violate Lorentz symmetry, but the question of whether m2&lt;0 and v&gt;c tachyonic neutrinos exist is an empirical question. It remains unresolved despite evidence from cosmic ray and other data that the electron neutrino has an effective mν2≈−0.25eV2, which would require that one or more mass states is also tachyonic. In 2013, the 3+3 model of the neutrino masses, which includes one tachyonic mass state, was proposed based on supernova SN 1987A neutrino data. Here, we update evidence for tachyonic electron neutrinos and the 3+3 model and discuss one test which could prove conclusive. The update of earlier evidence includes many new elements, including new data which make the earlier cosmic ray evidence more robust, new results on cosmic ray composition, the ankle of the spectrum, leptonic cosmic ray data, and the statistical significance of finding the three large neutrino masses stipulated in the 3+3 model. Barring a galactic supernova, which occur only around twice a century, a decisive test of the 3+3 model could involve observing an extragalactic supernova neutrino burst, that is, a cluster of neutrinos in a specific time window well beyond what chance would predict. Even though existing searches for such bursts have yielded only upper limits on the extragalactic supernova frequency within a certain distance, it is shown that the choice of a one-day window for possible neutrino clusters in time might be far more sensitive. A search using a one-day time window could be conducted using existing data, and if a signal is found it would confirm the 3+3 model. Of course, the absence of any day-long neutrino burst would not disprove the model, since it could mean only that the nearest supernova during the period when detectors were active was simply too far to be detected. Finally, apart from testing the 3+3 model, an alternative type of search is suggested using existing hadronic cosmic ray data (from the IceCube Collaboration) that might verify the tachyonic neutrino hypothesis.

Limits on Leptonic TeV Emission from the Cygnus Cocoon with Swift-XRT

γ-ray observations of the Cygnus Cocoon, an extended source surrounding the Cygnus X star-forming region, suggest the presence of a cosmic-ray accelerator reaching energies up to a few PeV. The very-high-energy (VHE; 0.1–100 TeV) γ-ray emission may be explained by the interaction of cosmic-ray hadrons with matter inside the Cocoon, but an origin of inverse Compton radiation by relativistic electrons cannot be ruled out. Inverse Compton γ-rays at VHE are accompanied by synchrotron radiation peaked in X-rays. Hence, X-ray observations may probe the electron population and magnetic field of the source. We observed 11 fields in or near the Cygnus Cocoon with the Neil Gehrels Swift Observatory’s X-Ray Telescope (Swift-XRT) totaling 110 ks. We fit the fields to a Galactic and extragalactic background model and performed a log-likelihood ratio test for an additional diffuse component. We found no significant additional emission and established upper limits in each field. By assuming that the X-ray intensity traces the TeV intensity and follows a spectrum, we obtained a 90% upper limit of F X < 8.7 × 10−11 erg cm−2 s−1 or <5.2 × 10−11 erg cm−2 s−1 on the X-ray flux of the entire Cygnus Cocoon between 2 and 10 keV depending on the choice of hydrogen column density model for the absorption. The obtained upper limits suggest that no more than one-quarter of the γ-ray flux at 1 TeV is produced by inverse Compton scattering, when assuming an equipartition magnetic field of ∼20 μG.

Constraints on the e± pair injection of pulsar halos: Implications from the Galactic diffuse multi-TeV gamma-ray emission

Diffuse gamma-ray emission (DGE) has been discovered over the Galactic disk in the energy range from sub-GeV to sub-PeV. While it is believed to be dominated by the pionic emission of cosmic ray hadrons via interactions with interstellar medium, unresolved gamma-ray sources may also be potential contributors. TeV gamma-ray halos around middle-aged pulsars have been proposed as such sources. Their contribution to DGE, however, highly depends on the injection rate of electrons and the injection spectral shape, which are not well determined based on current observations. The measured fluxes of DGE can thus provide constraints on the ${e}^{\ifmmode\pm\else\textpm\fi{}}$ injection of the pulsar halo population in turn. In this paper, we estimate the contribution of pulsar halos to DGE based on the Australia Telescope National Facility pulsar samples with taking into account the off-beam pulsars. The recent measurement on DGE by Tibet $\mathrm{AS}\ensuremath{\gamma}$ and an early measurement by Multiple Institution Los Alamos Gamma Ray Observatory (MILAGRO) are used to constrain the pair injection parameters of the pulsar halo population. Our result may be used to distinguish different models for pulsar halos.

Studies of Anomalous Phenomena in the Development of Electron-Nuclear Cascades in the EAS Cores Registered by a Modernized Complex Installation at Mountain Altitudes

Phenomena have been observed in mountain high-energy cosmic-ray experiments, namely, a delayed absorption of high-energy cascades initiated by cosmic-ray hadrons in a lead absorber at E0≳ 1014 eV (so-called long-flying component), a coplanarity of most energetic particles in the central region of γ-ray−hadron superfamilies, and the so-called Tien Shan effect in EAS cores at E0≳ 1016 eV s&gt;5 TeV. These effects are not described by theoretical models. The coplanarity is explained by the process of coplanar generation of most energetic secondary particles in interactions of superhigh-energy hadrons with the nuclei of air atoms. The other two phenomena are possibly explained with a high cross section for fragmentation-region charmed-hadron generation. To investigate these phenomena, a cosmic-ray detector array, including a very thick ionization calorimeter, is being upgraded to study EAS cores.

Where are Milky Way’s hadronic PeVatrons?

Observations of the Milky Way at TeV--PeV energies reveal a bright diffuse flux of hadronic cosmic rays and also bright point sources of gamma rays. If the gamma-ray sources are hadronic cosmic-ray accelerators, then they must also be neutrino sources. However, no neutrino sources have been detected. Where are they? We introduce a new population-based approach to probe Milky Way hadronic PeVatrons, demanding consistency between diffuse and point-source PeV-range data on cosmic rays, gamma rays, and neutrinos. For the PeVatrons, two extreme scenarios are allowed: (1) the hadronic cosmic-ray accelerators and the gamma-ray sources are the same objects, so that bright neutrino sources exist and improved telescopes can detect them, versus (2) the hadronic cosmic-ray accelerators and the gamma-ray sources are distinct, so that there are no detectable neutrino sources. The latter case is possible if hadronic accelerators have sufficiently thin column densities. We quantify present constraints and future prospects, showing how to reveal the nature of the hadronic PeVatrons.

Gamma‐ray production in supermassive black hole binary OJ 287

AbstractOJ 287 is one of the most studied BL Lac objects with very long optical measurements whose spectrum has been well measured through radio to X‐ray band. The most outstanding characteristic of OJ 287 is its 12‐year period, which is discovered in the optical range and has also been confirmed in the X‐ray band. OJ 287 is supposed to be a binary black hole system in which a secondary black hole passes the accretion disk of the primary black hole and produces two impact flashes per period. It has also been proposed to be a GeV–TeV source. Observations of OJ 287 in the GeV–TeV energy range reveal the variable γ‐ray connected with the flare activity of this object. The spectral energy distributions of blazars consist of two broad peaks. The first, lower frequency peak is due to the synchrotron emissions of relativistic electrons in the jet. Leptonic and hadronic emission mechanisms are considered to describe the second, higher frequency spectrum part. The inverse Compton emissions of the same electrons (synchrotron self‐Compton model) or combined with an external Compton mechanism are considered in the leptonic scenario. The last one supposes the existence of the external to jet photon cloud. The high‐energy spectrum part is also supposed to be generated due to the acceleration of the cosmic ray hadrons in shock produced by outflow, which expands and then collides with the wind of the primary black hole. The detection of GeV–TeV energy fluxes can help find the parameters of the configuration of the two‐black hole system.

A galactic breeze origin for the Fermi bubbles emission

ABSTRACT The origin of the Fermi bubbles, which constitute two gamma-ray emitting lobes above and below the Galactic plane, remains unclear. The possibility that this Fermi bubbles gamma-ray emission originates from hadronic cosmic rays advected by a subsonic Galactic outflow, or breeze, is here explored. The simulation of a breeze solution and subsequent cosmic ray transport is carried out using the hydrodynamical code, PLUTO, in combination with a cosmic ray transport code. The Galactic outflow model obtained is found to be compatible with both inferences of the decelerating outflow velocity profile of the gas in the Fermi bubbles region, and evidence for the presence of a large amount of hot ionized gas out in the Galactic halo region. Although simple, this model is found to be able to reproduce the observed Fermi-LAT energy flux at high Galactic latitudes. Following these results a prediction concerning the gamma-ray emission for 1–3 TeV photons is made for future comparison with CTA/SWGO measurements.

Diffuse γ-ray emission around the massive star forming region of Carina Nebula Complex

ABSTRACT We report the Fermi Large Area Telescope (Fermi-LAT) detection of the γ-ray emission toward the massive star forming region of Carina Nebula Complex (CNC). Using the latest source catalogue and diffuse background models, we found that the GeV γ-ray emission in this region can be resolved into three different components. The GeV γ-ray emission from the central point source is considered to originate from the η Carina (η Car). We further found the diffuse GeV γ-ray emission around the CNC which can be modelled by two Gaussian discs with radii of 0.4○ (region A) and 0.75○ (region B), respectively. The GeV γ-ray emission from both the regions A and B have good spatial consistency with the derived molecular gas in projection on the sky. The GeV γ-ray emission of region A reveals a characteristic spectral shape of the pion-decay process, which indicates that the γ-rays are produced by the interactions of hadronic cosmic rays with ambient gas. The γ-rays spectrum of region B has a hard photon index of 2.12 ± 0.02, which is similar to other young massive star clusters. We argue that the diffuse GeV γ-ray emission in region A and region B likely originate from the interaction of accelerated protons in clusters with the ambient gas.

Search for High-energy Neutrino Emission from Galactic X-Ray Binaries with IceCube

We present the first comprehensive search for high-energy neutrino emission from high- and low-mass X-ray binaries conducted by IceCube. Galactic X-ray binaries are long-standing candidates for the source of Galactic hadronic cosmic rays and neutrinos. The compact object in these systems can be the site of cosmic-ray acceleration, and neutrinos can be produced by interactions of cosmic rays with radiation or gas, in the jet of a microquasar, in the stellar wind, or in the atmosphere of the companion star. We study X-ray binaries using 7.5 yr of IceCube data with three separate analyses. In the first, we search for periodic neutrino emission from 55 binaries in the Northern Sky with known orbital periods. In the second, the X-ray light curves of 102 binaries across the entire sky are used as templates to search for time-dependent neutrino emission. Finally, we search for time-integrated emission of neutrinos for a list of 4 notable binaries identified as microquasars. In the absence of a significant excess, we place upper limits on the neutrino flux for each hypothesis and compare our results with theoretical predictions for several binaries. In addition, we evaluate the sensitivity of the next generation neutrino telescope at the South Pole, IceCube-Gen2, and demonstrate its power to identify potential neutrino emission from these binary sources in the Galaxy.

Gamma-ray emission from supermassive black hole binary OJ 287

OJ 287 is one of the most studied BL Lacs with very long optical measurements which spectrum has been well measured through radio to X-rays. OJ 287 is supposed to be a binary black hole system. Its secondary black hole passes the accretion disk of the primary black hole and produces two impact flashes per 12-year period. Observations of OJ 287 in the GeV – TeV energy range reveal the variable γ-ray flux connected with the flare activity of this object. The spectral energy distributions of BL Lac objects consist of two broad peaks. The Inverse Compton emission of the relativistic electrons in the jet or combined with an external Compton mechanism are considered in the leptonic scenario of second, higher frequency spectrum part generation. The last one supposes the existence of the external to jet photon cloud. Also, the second spectrum part is supposed to be generated due to the acceleration of the cosmic ray hadrons in expanding shock produced by outflow, which then collides with the wind of the primary black hole. The detection of GeV – TeV energy fluxes can help find the configuration parameters of the two-black hole system.

On the interpretation of the latest AMS-02 cosmic ray electron spectrum

The latest AMS-02 data on cosmic ray electrons show a break in the energy spectrum around 40 GeV, with a change in the slope of about 0.1. We perform a combined fit to the newest AMS-02 positron and electron flux data above 10 GeV using a semi-analytical diffusion model where sources includes production of pairs from pulsar wind nebulae (PWNe), electrons from supernova remnants (SNRs) and both species from spallation of hadronic cosmic rays with interstellar medium atoms. We demonstrate that within our setup the change of slope in the AMS-02 electron data is well explained by the interplay between the flux contributions from SNRs and from PWNe. In fact, the relative contribution to the data of these two populations changes by a factor of about 13 from 10 to 1000 GeV. The PWN contribution has a significance of at least 4σ, depending on the model used for the propagation, interstellar radiation field and energy losses. We checked the stability of this result against low-energy effects by solving numerically the transport equation, as well as adding possible breaks in the injection spectrum of SNRs. The effect of the energy losses alone, when the inverse Compton scattering is properly computed within a fully numerical treatment of the Klein-Nishina cross section, cannot explain the break in the e− flux data, as recently proposed in the literature.

Time-dependent Treatment of Cosmic-ray Spectral Steepening Due to Turbulence Driving

Abstract Cosmic-ray acceleration at non-relativistic shocks relies on scattering by turbulence that the cosmic rays drive upstream of the shock. We explore the rate of energy transfer from cosmic rays to non-resonant Bell modes and the spectral softening it implies. Accounting for the finite time available for turbulence driving at supernova-remnant shocks yields a smaller spectral impact than found earlier with steady-state considerations. Generally, for diffusion scaling with the Bohm rate by a factor η, the change in spectral index is at most η divided by the Alfvénic Mach number of the thermal sub-shock. For M A ≲ 50 it is well below this limit. Only for very fast shocks and very efficient cosmic-ray acceleration can the change in spectral index reach 0.1. For standard SNR parameters, it is negligible. Independent confirmation is derived by considering the synchrotron energy losses of electrons: if intense nonthermal multi-keV emission is produced, the energy loss, and hence the spectral steepening, is very small for hadronic cosmic rays that produce TeV-band gamma-ray emission.

Scaling violation in interaction of cosmic ray hadrons and the nature of the 3 PeV knee in the spectrum of primary cosmic rays

Energy spectra of the most energetic hadrons in the core region of extensive air showers (EASs) were studied in dependence on the EAS energy E 0 in the hybrid experiment HADRON at the Tien Shan mountain cosmic ray station. For the first time by direct measurement it was found in this experiment that the slope of the power energy spectrum of EAS hadrons diminishes itself locally, and the average hadron energy, correspondingly, increases between the E 0 borders 3 PeV and 20 PeV. Such behavior agrees with threshold appearance in EAS, in the same energy range, of a long-flying penetrative component which was earlier revealed at the Tien Shan station. Now we reconsider this Tien Shan result in comparison with the new data of modern collider experiments. The analysis permits to state unambiguously an astrophysical nature of the penetrative EAS component, and to discuss its probable connection with the origin of the famous knee in the energy spectrum of cosmic rays at E 0 ≃ 3 PeV.