Galileo versus Aristotle: the case of supernova 1987A

Most current supernova theories state that this phenomenon lasts a few seconds and ends with a bigfinal explosion.However, these theories do not take into account several experimental results obtained with neutrino and gravitational wave detectors during the explosion of SN1987A, the only supernova observed in a nearby galaxy in modern age. According to these experimental results the phenomenon is much more complex that envisaged by current theories, and has a duration of several hours. Indeed, SN1987A exploded on February 23, 1987, and two neutrino bursts, separated by 4.7 hours were detected: the first one at 2^h 52^m UT and the second one at 7^h 35^m UT. Furthermore, correlations between the neutrino and two gravitational wave detectors, ignored by most of the scientific community, were observed during the longer collapse time. Since the current standard theories, based on some rough simplifications, are a clear example of an Aristotelian attitude, still present in our days, we believe that a more Galilean attitude is necessary, being the only correct way for the progress of science.     

Problems of the detection of neutrino radiation from SN 1987A: Twenty years after

Basic characteristics of the “response” of underground neutrino detectors to the explosion of SN 1987A occurred on February 23, 1987, are presented. We discuss the evolution of our viewpoint on the interpretation of the results concerning the detection of neutrino radiation from the supernova over the past 20 years.     

A rotating collapsar and possible interpretation of the LSD neutrino signal from SN 1987A

We consider an improved rotational mechanism of the explosion of a collapsing supernova. We show that this mechanism leads to two-stage collapse with a phase difference of ～5 h. Based on this model, we attempt a new interpretation of the events in underground neutrino detectors on February 23, 1987, related to the supernova SN 1987A.     

A possible explanation of the second neutrino burst from SN 1987A

It is argued that the neutrino bursts registered on February 23.316 UT, 1987 signalized the transition of a fresh-borne neutron star into a superdense state. The neutron star is supposed to be formed approximately five hours before at February 23.12 UT in the supernova SN 1987a in the Large Magellanic Cloud.     

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.     

Neutrino bursts and gravitational waves experiments

Several experiments have been performed in many countries to observe gravitational waves or neutrino bursts. Since their simultaneous emission may occur in stellar collapses, we evaluate the effect of neutrino bursts on gravitational wave antennas and suggest the usefulness of a time correlation among the different detectors.     

The Neutrino Telescope Antares

Whilst the number of observed astrophysical sources of γ-rays is now moderately high, only three astrophysical objects have been studied with neutrinos, namely the Sun, a supernova (SN1987A) and the Earth (its atmosphere). However, astro-neutrinos may give a new boost to astrophysics, similar to the impressive progress provided during the last decades by γ-rays. The ANTARES collaboration aims to build a large neutrino telescope under the Mediterranean Sea at a depth of 2500 m. To reach this goal, a remarkable effort of R&D has been performed in recent years that has culminated in the deployment, connection and operation of two prototype strings. The final detector will be composed of 12 strings and will be ready by 2007.     

Detection of Solar Neutrinos

The present status of solar neutrino detection is reviewed. Results from the Homestake, Kamiokande, Super-Kamiokande, GALLEX and SAGE detectors all show a deficit when compared to recent standard solar model calculations. Two of these detectors, GALLEX and SAGE, have recently been checked with artificial 51Cr neutrino sources. It is shown that astrophysical scenarios to solve the solar neutrino problems are not favoured by the data. There is hope that the results of Super-Kamiokande and the forthcoming solar neutrino experiments can provide the answers to the open questions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Design,characterization, and sensitivity of the supernova trigger system at Daya Bay

Providing an early warning of galactic supernova explosions from neutrino signals is important in studying supernova dynamics and neutrino physics. A dedicated supernova trigger system has been designed and installed in the data acquisition system at Daya Bay and integrated into the worldwide Supernova Early Warning System (SNEWS). Daya Bay’s unique feature of eight identically-designed detectors deployed in three separate experimental halls makes the trigger system naturally robust against cosmogenic backgrounds, enabling a prompt analysis of online triggers and a tight control of the false-alert rate. The trigger system is estimated to be fully sensitive to 1987A-type supernova bursts throughout most of the Milky Way. The significant gain in sensitivity of the eight-detector configuration over a mass-equivalent single detector is also estimated. The experience of this online trigger system is applicable to future projects with spatially distributed detectors.     

Methods for point source analysis in high energy neutrino telescopes

Neutrino telescopes are moving steadily toward the goal of detecting astrophysical neutrinos from the most powerful galactic and extragalactic sources. Here we describe analysis methods to search for high energy point-like neutrino sources using detectors deep in the ice or sea. We simulate an ideal cubic kilometer detector based on real world performance of existing detectors such as AMANDA, IceCube, and ANTARES. An unbinned likelihood ratio method is applied, making use of the point spread function and energy distribution of simulated neutrino signal events to separate them from the background of atmospheric neutrinos produced by cosmic ray showers. The unbinned point source analyses are shown to perform better than binned searches and, depending on the source spectral index, the use of energy information is shown to improve discovery potential by almost a factor of two.     

Weibel Turbulence in Laboratory Experiments and GRB/SN Shocks

It has recently been realized that the Weibel instability plays a major role in the formation and dynamics of astrophysical shocks of gamma-ray bursts and supernovae. Thanks to technological advances in the recent years, experimental studies of the Weibel instability are now possible in laser-plasma interaction devices. We, thus, have a unique opportunity to model and study astrophysical conditions in laboratory experiments – a key goal of the Laboratory Astrophysics program. Here we briefly review the theory of strong non-magnetized collisionless GRB and SN shocks, emphasizing the crucial role of the Weibel instability and discuss the properties of radiation emitted by (isotropic) electrons moving through the Weibel-generated magnetic fields, which is referred to as the jitter radiation. We demonstrate that the jitter radiation field is anisotropic with respect to the direction of the Weibel current filaments and that its spectral and polarization characteristics are determined by microphysical plasma parameters. We stress that the spectral analysis can be used for accurate diagnostics of the plasma conditions in laboratory experiments and in astrophysical GRB and SN shocks.     

On the observability of high-energy neutrinos from gamma ray bursts

A method is presented for the identification of high-energy neutrinos from gamma ray bursts (GRBs) by means of a large-scale neutrino telescope. The procedure makes use of a time profile stacking technique of observed neutrino induced signals in correlation with satellite observations. By selecting a rather wide time window, a possible difference between the arrival times of the gamma and neutrino signals may also be identified. This might provide insight in the particle production processes at the source. By means of a toy model it will be demonstrated that a statistically significant signal can be obtained with a km³ scale neutrino telescope on a sample of 500 GRBs for a signal rate as low as 1 detectable neutrino for 3% of the bursts.     

高能中微子和极高能宇宙线起源天体的理论研究

极高能宇宙线一般指来自地外的能量高于1018电子伏特(eV)的高能质子与原子核,其起源的研究一直是高能天体物理和粒子天体物理领域的热点问题.近年随着一些大型探测器(如Pierre Auger天文台)的运行,极高能宇宙线的研究取得很大进展.然而由于极高能宇宙线事例相对较少及其在从源到地球传播过程中的复杂性(如与宇宙微波背景辐射以及磁场的作用),需要通过观测这些宇宙线在强子反应中产生的次级粒子(如中微子)来获得其起源的额外信息.最近,位于南极的IceCube中微子天文台探测到了54个能量分布在60TeV{3PeV内的中微子事例,开启了高能中微子天文学的新时代.在本文中,我们研究了高能中微子、极高能宇宙线的天体物理起源以及它们之间可能的联系.     

A WIMP detector with two-phase xenon

We describe an important new technique to search for WIMPs. This technique employs a method of background discrimination using double phase xenon as detector target. We describe the construction of a two-phase, 1-kg xenon detector. The detector will be installed at the underground laboratory in the Mt. Blanc tunnel, which provides a low background rate. A comparison between the sensitivity curve of our detector and the theoretical events limit from SUSY calculations is presented.     

Periodicities of the neutrino burst from Supernova 1987A

The neutrino burst from Supernova 1987A detected by Mont Blanc, Kamiokande II, IMB, and BAKSAN have been studied by Jurkevich's mathematical technique of search for periodicities. It is found that all the data exhibit 11±0.2 ms period. There are also other periods, but they are almost exact multiples of 11 ms. We suggests that the 11 ms period is the pulsation period of the neutron core of the supernova remnant. From the observed period of neutrino data it is also possible to predict the masses of the neutrinos.     

Astrophysical interpretation of small-scale neutrino angular correlation searches with IceCube

The IceCube Neutrino Observatory has discovered a diffuse all-flavor flux of high-energy astrophysical neutrinos. However, the corresponding astrophysical sources have not yet been identified. Neither significant point sources nor significant angular correlations of event directions have been observed by IceCube or other instruments to date. We present a new method to interpret the non-observation of angular correlations in terms of exclusions on the strength and number of point-like neutrino sources in generic astrophysical scenarios. Additionally, we constrain the presence of these sources taking into account the measurement of the diffuse high-energy neutrino flux by IceCube. We apply the method to two types of astrophysically motivated source count distributions: The first type is obtained by considering the cosmological evolution of the co-moving density of active galaxies, while the second type is directly derived from the gamma ray source count distribution observed by Fermi-LAT. As a result, we constrain the possible parameter space for both types of source count distributions.     

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.     

Type I X-ray Bursts Detected by the JEM-X Telescope Onboard the INTEGRAL Observatory in 2003–2015

We present the results of our analysis of the JEM-X/INTEGRAL data obtained from January 2003 to January 2015 aimed at searching for type I X-ray bursts from known and new bursters. Such bursts are caused by thermonuclear explosions on the surface of a neutron star. We have searched for bursts in the records of the count rate of the JEM-X detectors in the 3–20 keV energy band. We have separately reconstructed and analyzed the light curves of 104 X-ray bursters known to date based on the JEM-X data. A similar search for bursts was previously carried out in the 15–25 keV data from the IBIS/ISGRI telescope onboard the INTEGRAL observatory obtained in 2003–2009. We have continued to analyze the data from this telescope up until the observations in January 2015. The joint catalog of bursts detected by the two instruments includes 2201 events; their basic parameters are given. The large size of the sample of bursts makes it one of the most representative of the existing one and allows various statistical studies of bursts to be performed. In particular, we have constructed the dependence of the mean rate of type I bursts from bursters on the luminosity (accretion rate), revealed an appreciable burst rate from sources with a near-Eddington luminosity, and investigated the population of multiple bursts with a recurrence time much shorter than the time it takes for a critical mass of matter required for the initiation of an explosion to be accumulated on the neutron star surface. Almost all of the detected bursts are associated with already known bursters,we have found only one previously unknown burster, IGRJ17380-3749, in the archival data, and one more known, but poorly studied source, AX J1754.2-2754, has been identified as a burster. Several similar sources have previously been identified as bursters directly during the INTEGRAL observations.     

On detection of high-energy neutrinos from sources of gamma-ray bursts

We show that, contrary to a recent suggestion, fluxes of 30 GeV-1 TeV neutrinos that may accompany-ray bursts are at least a few orders of magnitude too weak to be detected by the current or planned neutrino detectors.