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The Tibet ASγ experiment provided the first measurement of the total diffuse gamma-ray emission from the Galactic disk in the sub-PeV energy range. Based on the analysis of TeV sources included in the H.E.S.S. Galactic Plane Survey catalog, we predict the expected contribution of unresolved pulsar-powered sources in the two angular windows of the Galactic plane observed by Tibet ASγ. We show that the sum of this additional diffuse component due to unresolved sources and the truly diffuse emission, due to cosmic-ray interaction with the interstellar medium, well saturates the Tibet data, without the need to introduce a progressive hardening of the cosmic-ray spectrum toward the Galactic center.

IceCube collaboration reported the first high-significance observation of the neutrino emission from the Galactic disk. The observed signal can be due to diffuse emission produced by cosmic rays interacting with interstellar gas but can also arise from a population of sources. In this paper, we evaluate both the diffuse and source contribution by taking advantage of gamma-ray observations and/or theoretical considerations. By comparing our expectations with IceCube measurements, we constrain the fraction of Galactic TeV gamma-ray sources (resolved and unresolved) with hadronic nature. In order to be compatible with the IceCube results, this fraction should be small, or the source proton energy cutoff should be well below the cosmic-ray proton knee. In particular, for a cutoff energy equal to 500 TeV, the fraction of hadronic sources should be less than ∼40% corresponding to a cumulative source flux Φ ν,s ≤ 2.6 × 10−10 cm−2 s−1 integrated in the 1–100 TeV energy range. This fraction reduces to ∼20% for energy cutoff reaching the cosmic-ray proton knee around 5 PeV.

We evaluate the diffuse gamma-ray flux at TeV energies produced by hadronic interactions of cosmic rays with the gas contained in the galactic disk. We consider different assumptions for the cosmic ray distribution, including the recently emerged possibility of a harder cosmic ray spectrum in the inner Galaxy. We show that observational data provided by Argo-YBJ, HESS, HAWC and Milagro, can already discriminate among different hyphoteses. The constraints can be strengthened if the contribution of sources not resolved by HESS is taken into account.

We describe a new generation of standard solar models (SSMs), Barcelona 2016 or B16 for short, that includes recent updates on some important nuclear reaction rates, a more consistent treatment of the equation of state and a novel and flexible treatment of opacity uncertainties. Two large sets of SSMs, each based on a different canonical set of solar abundances with high and low metallicity, are calculated and compared with different ensembles of solar observables including solar neutrinos, surface helium abundance, depth of convective envelope and sound speed profile.

In the last decades, a very important breakthrough has been brought about in the elementary particle physics by the discovery of the phenomenon of the neutrino oscillations, which has shown neutrino properties beyond the Standard Model. But a full understanding of the various aspects of the neutrino oscillations is far to be achieved. In this paper the theoretical background of the neutrino oscillation phenomenon is described, referring in particular to the paradigmatic models. Then the various techniques and detectors which studied neutrinos from different sources are discussed, starting from the pioneering ones up to the detectors still in operation and to those in preparation. The physics results are finally presented adopting the same research path which has been crossed by this long saga. The problems not yet fixed in this field are discussed, together with the perspectives of their solutions in the near future.

We present the predictions of updated standard solar models and we briefly discuss the solar composition problem, i.e. the conflict between helioseismology and standard solar models implementing the state-of-the-art photospheric abundances, emphasizing the importance of measuring neutrinos produced in the CNO cycle for its comprehension.

We analyze the subset of high energy neutrino events observed by IceCube above 60 TeV, combined with the information provided by passing muons, aiming to probe the flavor of cosmic neutrinos. First, we compare the observed track-to-shower ratio with the predictions for a cosmic neutrino population, taking into account the different production mechanisms and the uncertainties due to neutrino oscillations. Our results corroborate the hypotheses that cosmic neutrinos have been seen. In addition, we show that the possibility of neutrinos decay is disfavored at about 2σ level of significance for both the normal and inverted neutrino mass hierarchy.

The Borexino detector, located at the Laboratori Nazionali del Gran Sasso in Italy, is a radiopure 280 ton liquid scintillator detector with a primary goal to measure low-energy solar neutrinos created in the core of the Sun. These neutrinos are a consequence of nuclear fusion reactions in the solar core where Hydrogen is burned into Helium and provide a direct probe of the energy production processes, namely the proton-proton ( pp ) chain and the Carbon-Nitrogen-Oxygen (CNO) cycle. The fusion of Hydrogen in the case of the CNO cycle, which is expected to contribute in the order of less than 1% to the total solar energy, is catalyzed by Carbon, Nitrogen, and Oxygen directly depending on the abundances of these elements in the solar core. The measurement of CNO neutrinos is challenging due to the high spectral correlation with the decay electrons of the background isotope 210 Bi and the pep solar neutrino signal. The experimental achievement of thermal stabilization of the Borexino detector after mid 2016, has opened the possibility to develop a method to constrain the 210 Bi rate through its decay daughter and α emitter 210 Po which can be identified in Borexino with an efficiency close to 100 percent on an event-by-event basis. Moreover, the flux of pep neutrinos can be constrained precisely through a global analysis of solar neutrino data which is independent of the dataset used for the CNO analysis. This conference contribution is dedicated to the first experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun which is at the same time the dominant energy production mechanism in heavier stars compared to the Sun.

Thanks to the progress of neutrino physics, today we are able of exploiting neutrinos as a tool to study astrophysical objects. The latter in turn serve as unique sources of elusive neutrinos, which fundamental properties are still to be understood. This contribution attempts to summarize the latest results obtained by measuring neutrinos emitted from the Sun and geoneutrinos produced in radioactive decays inside the Earth, with a particular focus on a recent discovery of the CNO-cycle solar neutrinos by Borexino. Comprehensive measurement of the pp -chain solar neutrinos and the first directional detection of sub-MeV solar neutrinos by Borexino, the updated 8 B solar neutrino results of Super-Kamiokande, as well as the latest Borexino and KamLAND geoneutrino measurements are also discussed.

Borexino has been a neutrino detector based on ultrapure liquid scintillator, located at the Laboratori Nazionali del Gran Sasso, Italy. Its main scientific goal was the real-time measurement of solar neutrino fluxes, which play an irreplaceable role for the comprehension of the mechanisms powering our star. Over the past two years, the Borexino collaboration has pursued the improvement of the CNO flux measurement, obtaining further indications about the solar metallicity. In a parallel way, Borexino has demonstrated for the first time the possibility of exploiting the directional Cherenkov information, in a liquid scintillator detector, for the detection of sub-MeV solar neutrinos.