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1.
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   

2.
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   

3.
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   

4.
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 2h 52m UT and the second one at 7h 35m 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.  相似文献   

5.
The neutrino burst detected during supernova SN 1987A is explained in a strangeon star model, in which it is proposed that a pulsar-like compact object is composed of strangeons(strangeon:an abbreviation for "strange nucleon"). A nascent strangeon star's initial internal energy is calculated,with the inclusion of pion excitation(energy around 10~(53) erg, comparable to the gravitational binding energy of a collapsed core). A liquid-solid phase transition at temperature ~ 1-2MeV may occur only a few tens of seconds after core collapse, and the thermal evolution of a strangeon star is then modeled.It is found that the neutrino burst observed from SN 1987A can be reproduced in such a cooling model.  相似文献   

6.
The properties of the neutrino burst generated by massive 1.5–2M collapsing stellar iron-oxygen cores are discussed. Special attention is given to the neutrino heat conductivity theory which allows us to calculate the transport of neutrinos through the collapsing stellar core up to the formation and during the first seconds of cooling of a hot hydrostatic neutron star. The theoretical predictions seem to be in good agreement with both the KAMIOKANDE II and IMB data on the neutrino burst detected from SN 1987A. The most reliable constraint on the neutrino rest mass is shown to bem v <20–30eV, while the safest upper limit on the neutrino magnetic moment, µ v < 10–11 Bohr magnetons, results rather from the cooling of white dwarfs than from the SN 1987A neutrino data.Presented to the 13th International Conference Neutrino-88, Boston, U.S.A., 5–11 June, 1988.  相似文献   

7.
The temporal structure of the neutrino scintillation detector response to the supernova explosion signal is calculated, taking into account the duration and the spectrum of the supernova neutrino radiation and also the neutrino rest-mass.  相似文献   

8.
We consider the time, angular, and energy distributions of SN 1987A events and discuss the quality of their agreement with the expectations. A global interpretation is made by considering a simple model based on the standard scenario for the explosion. Despite the contrasting and confusing indications, a straightforward fit to the data provides a result that does not contradict but rather supports the expectations. The calculated electron antineutrino flux is applied to predict the relic neutrino signal. The article was translated by the authors.  相似文献   

9.
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.  相似文献   

10.
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.  相似文献   

11.
In this paper, the neutrino mass has been determined from SN1987a observation in a manner that the simultaneity of neutrino emission is not regarded as the starting point, but is itself defined through the analysis by Monte-Carlo simulation. The result is that the neutrino mass lies in 3–4 eV, possiblym v 3.6 eV. Neutrino luminosity variation and neutrino spectrum are also obtained. Comparison with theories gives further support to the mass determination, and also predicts the mass of progenitor star of SN1987a to be in the range of 12–25M .The project supported by the National Natural Science Foundation of China.  相似文献   

12.
A quasi-one-dimensional hydrodynamic model for the collapse of a rotating iron stellar core is used to determine the neutrino spectra in the limiting case of total transparency to neutrino emission (without any deposition effect). The derived spectra allow the previously constructed spectra used to theoretically estimate the number of events in the LSD underground neutrino detector from SN 1987A to be refined. At typical iron stellar core parameters, including those that characterize the core rotation specified in the initial conditions of the model, this number has turned out to be 1.6, which is close in order of magnitude to its experimental value of 5. Here, we compare in detail these results by assuming that the transparency of the collapsing iron core itself could be attributable to the development of its three-dimensional dynamical instability—the subject of future theoretical studies. The physical formulation of the problem coincides closely with the collapse model proposed in our previous paper, where the above number of events turned out to be 0.5. We have confirmed the previously published results with regard to the neutrino spectra, including the significant superiority of electron neutrinos over electron antineutrinos in them. The hydrostatically equilibrium configuration (a rotating collapsar) obtained in our model calculation is discussed in comparison with self-similar solutions that are close in physical formulation of the problem. This result seems a nontrivial consequence of the included rotation effects that hinder nonstop collapse established in the mentioned self-similar solutions.  相似文献   

13.
In recent papers it was claimed that SN 1987A data supports the existence of 4.0 eV and 21.4 eV active neutrino mass eigenstates, and it was suggested that such large active neutrino masses could be made consistent with existing constraints including neutrino oscillation data and upper limits on the neutrino flavor state masses. The requirement was that there exist a pair of sterile neutrino mass states nearly degenerate with the active ones, plus a third active-sterile doublet that is tachyonic (m 2<0). Here, independent evidence is presented for the existence of sterile neutrinos with the previously claimed masses based on fits to the dark matter distributions in the Milky Way galaxy and four clusters of galaxies. The fits are in excellent agreement with observations within the uncertainties of the masses. In addition, sterile neutrinos having the suggested masses address the “cusp” problem and the missing satellites problem, as well as that of the “top down” scenario of structure formation—previously a chief drawback of HDM particles. Nevertheless, due to the highly controversial nature of the claim, and the need for two free parameters in the dark matter fits, additional confirming evidence will be required before it can be considered proven.  相似文献   

14.
We present spectroscopic and photometric observations of the peculiar Type II supernova (SN) 1998A. The light curves and spectra closely resemble those of SN 1987A, suggesting that the SN 1998A progenitor exploded when it was a compact blue supergiant. However, the comparison with SN 1987A also highlights some important differences: SN 1998A is more luminous and the spectra show bluer continua and larger expansion velocities at all epochs. These observational properties indicate that the explosion of SN 1998A is more energetic than SN 1987A and more typical of Type II supernovae. Comparing the observational data with simulations, we deduce that the progenitor of SN 1998A was a massive star  (∼25 M⊙)  with a small pre-supernova radius  (≲6 × 1012 cm)  . The Ba  ii lines, unusually strong in SN 1987A and some faint II-P events, are almost normal in the case of SN 1998A, indicating that the temperature plays a key role in determining their strength.  相似文献   

15.
Utrobin  V. P. 《Astronomy Letters》2005,31(12):806-815
Astronomy Letters - Our study of the photometric and spectroscopic observations of SN 1987A based on the hydrodynamic modeling of its bolometric light curve and nonstationary hydrogen kinetics and...  相似文献   

16.
Twenty three years ago on February 23, 1987, the explosion of the SN in the L.M.C. was observed both optically and by underground detectors. The optical observations were done in Chile and Australian observatories while the neutrino burst was detected by several underground experiments in the Northern Hemisphere, running at that time: Mt. Blanc in Italy, Kamioka in Japan, and Baksan in Russia and IMB in the USA. For the first time in the history of human existence, an astrophysical phenomenon has been observed in underground detectors. In this astrophysical event, the Mt. Blanc experiment detected five pulses on-line that were not at the same time, as detected by the other three detectors around five hours later. It is still not clear to astrophysicists why two bursts at two different times have been detected and how an SN can generate two neutrino bursts. After 23 years a model has proposed an explanation for a double stage collapse at two different times, as recently suggested by V.S. Imshennik and O. Ryazhskaya. In this paper, a detailed occurrence of something strange that happened on February 23rd is presented while most of the scientific information has been exhibited in other published papers.  相似文献   

17.
Nonlinear processes describing the interaction of neutrinos with collective plasma oscillations and the excitation of plasma turbulence by a large neutrino flux is discussed. The excitation considered is the inverse processes of neutrino emission by plasma waves first considered by Tsytovich (V.N. Tsytovich, Soviet Fiz. Dokl. 9 (1965) 1114). The process is similar to a beam plasma instability considered as inverse Landau damping in which the usual electromagnetic interactions are important. In the neutrino beam relaxation the weak interaction can play a similar role. We emphasize here the possibility of another process namely the interaction of an intense neutrino flux with a strongly turbulent plasma. The turbulence can also be assumed to be due to the shock produced at the early stages of a type II supernova (SN) explosion. The scattering of the neutrinos in the turbulent plasma is shown to be sufficient for transferring momentum and energy from the neutrino flux to the plasma causing the shock to continue moving outward and eventually creating the blow-off of the mantle of the star producing type II SN.  相似文献   

18.
Light-echo measurements show that SN 1987A is 425 pc behind the LMC disk. It is continuing to move away from the disk at 18 km s-1. Thus, it has been suggested that SN 1987A was ejected from the LMC disk. However, SN 1987A is a member of a star cluster, so this entire cluster would have to have been ejected from the disk. We show that the cluster was formed in the LMC disk, with a velocity perpendicular to the disk of about 50 km s-1. Such high-velocity formation of a star cluster is unusual, having no known counterpart in the Milky Way.  相似文献   

19.
Three decades have passed since the supernova SN 1987A was observed in the Large Magellanic Cloud, inside which the product is most likely a neutron star (NS) formed in the core collapse explosion.Although lots of observations with sensitive radio telescopes have taken place, astronomers have not yet detected any evidence for a radio pulsar around the remnant of 1987A. To investigate pulsars inside the SN remnants, we calculate the cut-off oscillation frequency of the plasma around the presumed NS inside SN1987A, as shown to be about 33 GHz at present (2018 CE), which is much higher than the favorite “searching window” (e.g. L-band ∼ 1.4 GHz) of radio pulsar surveys that have been commonly exploited by astronomers. Since radio waves with frequencies lower than the plasma cut-off frequency cannot penetrate the SN remnant media, we suggest that astronomers use higher frequency bands to search for a pulsar in SN 1987A.Furthermore, with the expansion of SN remnant media, we find that the plasma cut-off frequency can decay to the L-band (1.4 GHz) in the future. The strategy of finding a pulsar of SN 1987A is that either the high frequency bands of radio telescopes, or the high energy detections at Gamma-ray and X-ray bands by space satellites are applied.  相似文献   

20.
We present the spectrum of the supernova SN1987L in NGC 2336 over the wavelength range 4000–9700 Å as recorded in one 500 s exposure on 20–21 October, 1987. This spectrum was taken using the new Faint Object Spectrograph on the 4.2 m William Herschel Telescope (WHT) at the Observatorio del Roque de los Muchachos.We conclude that SN1987L was a type Ia supernova, and approximately 100 days post maximum at the time of the observation.  相似文献   

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