共查询到20条相似文献，搜索用时 46 毫秒
1.
T. J. Mazurek 《Astrophysics and Space Science》1975,35(1):117-135
Typically collapsing supernova hydrodynamic computations assume LTE neutrino transport andimpose photon-like behavior, i.e., fix the neutrino chemical potentials at zero. The validity of the latter condition is investigated in the diffusion approximation to transport. A coupled system of diffusion equations for energy and lepton number is solved in a collapsing supernova ambience. The results indicate a substantial growth in the neutrino chemical potential for densities above 1012 gm cm?3. The rate of energy transport is affected significantly by the concomitant increases in Fermi integrals and gradients in chemical potential counter to those of temperature. It is found that the extent of neutrino particle/antiparticle interaction also affects energy diffusion rates. Thus the photon-like condition on neutrino transport may misrepresent supernova energetics substantially. An extension of the usual Sn transport to include lepton characteristics is deemed necessary for a definitive answer to the neutrino transport supernova question. 相似文献
2.
3.
The Fermi γ-ray space telescope reported the observation of several Galactic supernova remnants recently, with the γ-ray spectra well described by hadronic pp collisions. The possible neutrino emissions from these Fermi detected supernova remnants are discussed in this work, assuming the hadronic origin of the γ-ray emission. The muon event rates induced by the neutrinos from these supernova remnants on typical km3 neutrino telescopes, such as the IceCube and the KM3NeT, are calculated. The results show that for most of these supernova remnants the neutrino signals are too weak to be detected by the on-going or up-coming neutrino experiment. Only for the TeV bright sources RX J1713.7-3946 and possibly W28 the neutrino signals can be comparable with the atmospheric background in the TeV region, if the protons can be accelerated to very high energies. The northern hemisphere based neutrino telescope might detect the neutrinos from these two sources. 相似文献
4.
We present a real-time supernova neutrino burst monitor at Super-Kamiokande (SK). Detecting supernova explosions by neutrinos in real time is crucial for giving a clear picture of the explosion mechanism. Since the neutrinos are expected to come earlier than light, a fast broadcasting of the detection may give astronomers a chance to make electromagnetic radiation observations of the explosions right at the onset. The role of the monitor includes a fast announcement of the neutrino burst detection to the world and a determination of the supernova direction. We present the online neutrino burst detection system and studies of the direction determination accuracy based on simulations at SK. 相似文献
5.
The current supernova detection technique used in IceCube relies on the sudden deviation of the summed photomultiplier noise rate from its nominal value during the neutrino burst, making IceCube a ≈3 Megaton effective detection volume - class supernova detector. While galactic supernovae can be resolved with this technique, the supernova neutrino emission spectrum remains unconstrained and thus presents a limited potential for the topics related to supernova core collapse models.The paper elaborates analytically on the capabilities of IceCube to detect supernovae through the analysis of hits in the detector correlated in space and time. These arise from supernova neutrinos interacting in the instrumented detector volume along single strings. Although the effective detection volume for such coincident hits is much smaller (?35 kton, about the scale of SuperK), a wealth of information is obtained due to the comparatively low rate of coincident noise hits. We demonstrate that a neutrino flux from a core collapse supernova will produce a signature enabling the resolution of rough spectral features and, in the case of a strong signal, providing indication on its location.We further discuss the enhanced potential of a rather modest detector extension, a denser array in the center of IceCube, within our one dimensional analytic calculation framework. Such an extension would enable the exploration of the neutrino sky above a few GeV and the detection of supernovae up to a few 100’s of kilo parsec. However, a 3-4 Mpc detection distance, necessary for routine supernova detection, demands a significant increase of the effective detection volume and can be obtained only with a more ambitious instrument, particularly the boosting of sensor parameters such as the quantum efficiency and light collection area. 相似文献
6.
We calculated the expected neutrino signal in Borexino from a typical Type II supernova at a distance of 10 kpc. A burst of around 110 events would appear in Borexino within a time interval of about 10 s. Most of these events would come from the reaction channel
, while about 30 events would be induced by the interaction of the supernova neutrino flux on 12C in the liquid scintillator. Borexino can clearly distinguish between the neutral-current excitations 12C(ν,ν′)12C* (15.11 MeV) and the charged-current reactions 12C(νe,e−)12N and
, via their distinctive event signatures. The ratio of the charged-current to neutral-current neutrino event rates and their time profiles with respect to each other can provide a handle on supernova and non-standard neutrino physics (mass and flavor oscillations). 相似文献
7.
H.-J. Haubold S. Gottlber J. P. Mücket V. Müller B. Kmpfer 《Astronomische Nachrichten》1987,308(6):329-331
Implications from the available information on the supernova SN 1987 A are discussed for the supernova models. We derive an upper bound of 10–25 eV for the neutrino rest mass. 相似文献
8.
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. 相似文献
9.
The sterile neutrino mechanisms for pulsar natal kicks are reanalyzed. The necessary strength of the magnetic field generated in a supernova explosion is shown to have been underestimated significantly in previous works. An alternative mechanism for pulsar natal kicks involving only standard neutrinos in which the outgoing neutrino flux in a supernova explosionwith the generation of a strong toroidal magnetic field leads to a magnetic field redistribution in the ??upper?? and ??lower?? hemispheres of the supernova envelope is discussed. The emerging magnetic field pressure asymmetry can produce a pulsar natal kick. 相似文献
10.
Zhao Gang Zhao Yong-heng Huang Jia-sheng Feng Long-long Huang Ke-liang Peng Qiu-he Lu Tan 《Chinese Astronomy and Astrophysics》1988,12(4):294-297
We carried out a Monte Carlo simulation calculation on the observed data of neutrino events of the supernova SN1987A. Our results show that the best value for the rest-mass of neutrino is 3–4 eV. We also calculated the light curve of the neutrino bursts and the energy spectrum.Our results impose constraints on the rest-mass of neutrino and the mass of the precursor of SN 1987A. 相似文献
11.
The remnant resulting from the merger of two neutron stars produces neutrinos in copious amounts. In this paper we present the neutrino emission results obtained via Newtonian, high-resolution simulations of the coalescence event. These simulations use three-dimensional smoothed particle hydrodynamics together with a nuclear, temperature-dependent equation of state and a multiflavour neutrino leakage scheme. We present the details of our scheme, discuss the neutrino emission results from a neutron star coalescence and compare them with the core-collapse supernova case where neutrino emission has been studied for several decades. The average neutrino energies are similar to those in the supernova case, but contrary to the latter, the luminosities are dominated by electron-type antineutrinos that are produced in the hot, neutron-rich, thick disc of the merger remnant. The cooler parts of this disc contain substantial fractions of heavy nuclei, which, however, do not influence the overall neutrino emission results significantly. Our total neutrino luminosities from the merger event are considerably lower than those found in previous investigations. This imposes constraints on the ability of neutron star mergers to produce a gamma-ray burst via neutrino annihilation. The neutrinos are emitted preferentially along the initial binary rotation axis, an event seen 'pole-on' would appear much brighter in neutrinos than a similar event seen 'edge-on'. 相似文献
12.
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. 相似文献
13.
We analyze the influence of neutrino helicity conversion, ν
L → ν
R, on the neutrino flux from a supernova attributable to the interaction of the Dirac neutrino magnetic moment with a magnetic
field.We show that if the neutrino has a magnetic moment in the interval 10−13μB < μν < 10−12μB and provided that a magnetic field of ∼1013–1014 G exists in the supernova envelope, a peculiar kind of time evolution of the neutrino signal from the supernova attributable
to the resonance transition ν
L → ν
R in the magnetic field of the envelope can appear. 相似文献
14.
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. 相似文献
15.
Based on the magnetorotational model of a supernova explosion with core collapse, we investigate the significant processes of neutrino heating of the supernova shock. These processes should be taken into account in self-consistent modeling, since the neutrino heating mechanism is capable of increasing the explosion efficiency. We show that, even in the presence of a strong magnetic field (B ～ 1015 G) in the shock formation region, the heating rate is determined with good accuracy by the absorption and emission of neutrinos in direct URCA processes. Moreover, the influence on them of a magnetic field is reduced to insignificant corrections. 相似文献
16.
Expressions for the source and collision terms of the neutrino transport equation relevant to the neutrino transport supernova model are derived in the framework of the theory of neutral currents. In particular we study the capture and emission of neutrini (and anti-neutrini) by free nucleos, the inelastic scattering by free nucleons, the coherent scattering by nuclei, as well as the corresponding muonic processes.We also derive an analytical formula for the neutrino scatteringrate on electrons, valid for large electron degeneracy. 相似文献
17.
Probhas Raychaudhuri 《Astrophysics and Space Science》1972,19(1):145-149
It is pointed out that the all old supernova remnants are not in general sources of soft X-ray emission. Again it is pointed out that the galactic radio spur (Cetus arc) may be an old supernova remnant but it has already ceased to be a source of X-ray emission. Finally X-ray flux from Vela is ostimated from cooling rate of neutron star by neutrino emission. The results agree approximately with the observed X-ray flux from Vela X. 相似文献
18.
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. 相似文献
19.
Identifying the accelerators that produce the Galactic and extragalactic cosmic rays has been a priority mission of several generations of high energy gamma ray and neutrino telescopes; success has been elusive so far. Detecting the gamma-ray and neutrino fluxes associated with cosmic rays reaches a new watershed with the completion of IceCube, the first neutrino detector with sensitivity to the anticipated fluxes, and the construction of CTA, a ground-based gamma ray detector that will map and study candidate sources with unprecedented precision. In this paper, we revisit the prospects for revealing the sources of the cosmic rays by a multiwavelength approach; after reviewing the methods, we discuss supernova remnants, gamma ray bursts, active galaxies and GZK neutrinos in some detail. 相似文献
20.
The effects of ion screening in stellar core collapses are investigated based on a new progenitor star model.Simulation results show that ion screening slightly affects the leptons and decreases explosion energy,which is a negative factor for energy transfer supernova explosions.We also investigate the effect on type Ⅱ-supernova explosions of neutrino-nucleus elastic scattering based on the new progenitor star model.It is shown that,compared with the previously calculated results,neutrinos-nucleus elastic scattering in stellar core collapses is more severe,leading to an obvious reduction of the neutrino leakage energy loss and an increase of supernova explosion energy. 相似文献