The ANTARES telescope neutrino alert system

The ANTARES telescope has the capability to detect neutrinos produced in astrophysical transient sources. Potential sources include gamma-ray bursts, core collapse supernovae, and flaring active galactic nuclei. To enhance the sensitivity of ANTARES to such sources, a new detection method based on coincident observations of neutrinos and optical signals has been developed. A fast online muon track reconstruction is used to trigger a network of small automatic optical telescopes. Such alerts are generated for special events, such as two or more neutrinos, coincident in time and direction, or single neutrinos of very high energy.     

Neutrino fluxes from a core-collapse supernova in a model with three sterile neutrinos

The characteristics of the gravitational collapse of a supernova and the fluxes of active and sterile neutrinos produced during the formation of its protoneutron core have been calculated numerically. The relative yields of active and sterile neutrinos in corematter with different degrees of neutronization have been calculated for various input parameters and various initial conditions. A significant increase in the fraction of sterile neutrinos produced in superdense core matter at the resonant degree of neutronization has been confirmed. The contributions of sterile neutrinos to the collapse dynamics and the total flux of neutrinos produced during collapse have been shown to be relatively small. The total luminosity of sterile neutrinos is considerably lower than the luminosity of electron neutrinos, but their spectrum is considerably harder at high energies.     

太阳中微子"亏缺"与非标准太阳模型

系统阐述了太阳中微子“亏缺”问题出现的背景,包括介绍标准太阳模型,太阳内部的相聚变反应,太阳中微子能谱和流量的理论估算,以及太阳中微子探测实验和结果。讨论了为解释太阳中微子“亏缺”而提出的各种非标准太阳模型以及近年来愈益受到重视的中微子振动问题。     

The dogma of matters neutrino-transparency

In this paper the observed underrepresentation of solar neutrinos in the various detector experiments performed is tentatively interpreted as a result of a substantial and often variable obsorption of neutrinos by various layers of the Sun, contrary to the dogma of neutrino-transparency by matter.     

Stopping power of matter and energy losses of solar neutrinos

The effects of neutrino mass and oscillations are investigated in the calculations of energy losses of solar neutrinos. In these calculations, we take into account the full energy dependence of the stopping power of matter for neutrinos. The case of Majorana neutrinos are also investigated. It is found that the total losses of energy of solar neutrinos are too small to account for the solar neutrino problem.     

A search for astrophysical burst signals at the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) has confirmed the standard solar model and neutrino oscillations through the observation of neutrinos from the solar core. In this paper we present a search for neutrinos associated with sources other than the solar core, such as gamma-ray bursts and solar flares. We present a new method for looking for temporal coincidences between neutrino events and astrophysical bursts of widely varying intensity. No correlations were found between neutrinos detected in SNO and such astrophysical sources.     

History of neutrino telescope/astronomy

Neutrinos represent a new window to the Universe. In this paper we discuss the attempts to detect neutrinos, starting with the Homestake experiment, which showed the deficit of solar neutrinos. The detection of neutrinos from SN 1987A gave a new impetus to neutrino research. By using successive generations of neutrino detectors it was possible to show that the solar neutrino deficit could be explained by a flavor change of massive neutrinos. With the latest detector, kamLAND, it is possible to investigate the interior of the Earth through the detection of geoneutrinos.     

Study on the possible detection of Gamma Ray Bursts with the ANTARES neutrino telescope

The ANTARES telescope, currently in construction, is aiming to detect high energy neutrinos. Data from the first line of the detector, which became operational recently, demonstrates that the nominal time and space resolutions are achieved. Various models predict the emission of high energy neutrinos from astrophysical sources such as Supernova Remnants, Microquasars, Active Galactic Nuclei and Gamma Ray Bursts. With the custom designed data acquisition system of this detector, in combination with the existing satellite alert systems, the ANTARES telescope has an increased sensitivity for neutrinos from Gamma Ray Bursts compared to conventional time independent sources. Gabrielle Lelaizant on behalf of the ANTARES Collaboration.     

Neutrino Tomography – Learning About The Earth’s Interior Using The Propagation Of Neutrinos

Because the propagation of neutrinos is affected by the presence of Earth matter, it opens new possibilities to probe the Earth’s interior. Different approaches range from techniques based upon the interaction of high energy (above TeV) neutrinos with Earth matter, to methods using the MSW effect on the oscillations of low energy (MeV to GeV) neutrinos. In principle, neutrinos from many different sources (sun, atmosphere, supernovae, beams etc.) can be used. In this talk, we summarize and compare different approaches with an emphasis on more recent developments. In addition, we point out other geophysical aspects relevant for neutrino oscillations.     

On the detection of ultra high energy neutrinos with the Auger observatory

We show that the Auger Air Shower Array has the potential to detect neutrinos of energies in the 10¹⁹ eV range through horizontal air showers. Assuming some simple conservative trigger requirements, we obtain the acceptance for horizontal air showers as induced by high energy neutrinos by two alternative methods and we then give the expected event rates for a variety of neutrino fluxes as predicted in different models which are used for reference.     

Neutrinos in the early universe

The neutrinos from the Big Bang or the Cosmic Neutrino Background (CNB) carry precious information from the early epoch when our universe was only 1 s old. Although not yet directly detected, CNB may be revealed indirectly through cosmological observations due to neutrino important cosmological influence.We review the cosmological role of neutrinos and the cosmological constraints on neutrino characteristics. Namely, we discuss the impact of neutrinos in the early universe: the cosmic expansion, neutrino decoupling, the role of neutrinos in the primordial production of light elements, leptogenesis, etc. We briefly discuss the role of neutrino at later stages of the universe.Due to the considerable cosmological influence of neutrinos, cosmological bounds on neutrino properties from observational data exist. We review the cosmological constraints on the effective number of neutrino species, neutrino mass and mixing parameters, lepton number of the universe, presence of sterile neutrino, etc.     

Effect of non-zero rest-mass of neutrinos on clustering in the early universe

This paper discusses the effect of neutrinos with non-zero rest-mass on the clustering process in the early universe. The early universe is regarded as a two-component fluid, one component being the de-coupled neutrinos, and the other being matter and radiation, between the two there is only the gravitational coupling. The main conclusions are: (1) such neutrinos will cause clustering of matter before the epoch of re-combination; (2) the mass so clustered will be in the range of the mass of clusters of galaxies; (3) there exists a preferential clustering scale, corresponding to the earliest onset of Jeans instability; (4) if the rest-mass is below a certain value, then there will be no effect.     

Rotational evolution of protoneutron stars with hyperons: spin up or not?

We study the evolution of a rigidly rotating protoneutron star (PNS) with hyperons and nucleons or solely nucleons in its core due to the escape of trapped neutrinos. As the neutrinos escape, the core nucleonic neutron star (NS) expands and the stellar rotation slows. After the neutrinos escape, the range of the spin periods is narrower than the initial one, but the distribution is still nearly uniform. A PNS with hyperons, at the late stage of its evolution, keeps shrinking and spinning up until all the trapped neutrinos escape. Consequently, the distribution of the stellar initial spin periods is skewed towards shorter periods. If the hyperonic star is metastable, its rotational frequency accelerates distinguishedly before it collapses to a black hole.     

A model independent approach to future solar neutrino experiments

We discuss here what model independent information about properties of neutrinos and of the sun can be obtained from future solar neutrino experiments (SNO, Super-Kamiokande). It is shown that in the general case of transitions of solar ν_e's into νμ and/or ντ the initial ⁸B neutrino flux can be measured by the observation of NC events. From the CC measurements the ν_e survival probability can be determined as a function of neutrino energy. The general case of transitions of solar ν_e's into active as well as sterile neutrinos is considered. A number of relations between measurable quantities the test of which will allow to answer the question whether there are sterile neutrinos in the solar neutrino flux on the earth are derived. Transitions of solar ν_e's into active and sterile states due to neutrino mixing and Dirac magnetic moments or into active left-handed neutrinos and active right-handed antineutrinos due to neutrino mixing and Majorana transition magnetic moments are also considered. It is shown that future solar neutrino experiments will allow to distinguish between the cases of Dirac and Majorana magnetic moments.     

Galactic PeV neutrinos

The IceCube experiment has detected two neutrinos with energies between 1 and 10 PeV. They might have originated from Galactic or extragalactic sources of cosmic rays. In the present work we consider hadronic interactions of the diffuse very high energy cosmic rays with the interstellar matter within our Galaxy to explain the PeV neutrino events detected in IceCube. We also expect PeV gamma ray events along with the PeV neutrino events if the observed PeV neutrinos were produced within our Galaxy in hadronic interactions. PeV gamma rays are unlikely to reach us from sources outside our Galaxy due to pair production with cosmic background radiation fields. We suggest that in future with simultaneous detections of PeV gamma rays and neutrinos it would be possible to distinguish between Galactic and extragalactic origins of very high energy neutrinos.     

Sterile neutrinos as dark matter in clusters and galaxies

The recent analysis of MiniBooNE experiment suggests that a better fit of the data arises if there are 2 types of sterile neutrinos. If the sterile neutrinos were produced during the early epoch of the Big Bang, they would be slightly degenerate. I show that the existence of 2 types slightly degenerate sterile neutrinos can fully explain the dark matter problem, the cusp problem, the hot gas density profile in clusters and the rotation curves of galaxies.     

Neutrino-Astronomy with the Macro Experiment at Gran Sasso

The MACRO experiment at Gran Sasso is collecting muons since February 1989. These muons are induced by charged current interactions of atmospheric and, possibly, astrophysical muon neutrinos below the apparatus. A search has been made for discrete astrophysical sources of VHE and UHE neutrinos using the upward going muons direction information. Given the large area and the long period of data taking MACRO is, at the moment, able to set very competitive upper limits to the flux of neutrinos from most of the sources considered in the search. This revised version was published online in July 2006 with corrections to the Cover Date.     

Kinetic equations for neutrino spin- and type-oscillations in a medium

Quantum kinetic equations for the distribution function of massive Dirac neutrinos have been obtained. They describe neutrino spin- and type-oscillations in a medium. The processes of elastic and inelastic scattering of neutrinos with medium components as well as -processes have been taken into account. Applications of developed equations for stellar collapse are discussed.     

Studies on the evolved carbon cores

Physical conditions prevalent in a degenerate carbon plasma lead to the enhancement of the carbon-carbon thermonuclear reaction rates. Nuclear energy generation rate in the carbon core is thereby augmented. The possible dissipation of energy due to pair-annihilation neutrinos, plasma neutrinos and neutrino bremsstrahlung are considered. Neutral current contribution to these weak processes are also taken into account. It is suggested that the enhanced nuclear gene-ration rate in the evolved core might halt the core collapse for a time, thus necessitating a reassessment of the phenomenon of core collapse as a precursor of carbon detonation supernova events.     

Observational constraints of sterile neutrinos in galaxies

We study a model in which degenerate sterile neutrinos account for galactic dark matter. We fit the rotation curves of 5 dwarf galaxies with the degenerate sterile neutrinos in hydrostatic equilibrium. Also we estimate the range of sterile neutrino mass by calculating the upper and lower bounds of the mass densities of sterile neutrino halos in the outermost regions of 21 normal galaxies. The observed rotation curves of 5 dwarf galaxies and 21 normal galaxies are consistent with having sterile neutrinos with mass (26–30) eV, and the similarity of the rotation curves of different galaxies emerges naturally in our model.