Observation Of SN 1987A Research Articles

Massive Majorons and constraints on the Majoron-neutrino coupling

We revisit a singlet Majoron model in which neutrino masses arise from the spontaneous violation of lepton number. If the Majoron obtains a mass of order MeV, it can play the role of dark matter. We discuss constraints on the couplings of the massive Majoron with masses of order MeV to neutrinos from supernova data. In the dense supernova core, Majoron-emitting neutrino annihilations are allowed and can change the signal of a supernova. Based on the observation of SN1987A, we exclude a large range of couplings from the luminosity and the deleptonization arguments, taking the effect of the background medium into account. If the Majoron mass does not exceed the Q-value of the experiment, the neutrino-Majoron couplings allow for neutrinoless double beta decay with Majoron emission. We derive constraints on the couplings for a Majoron mass of order MeV based on the phase space suppression and the diminishing signal-to-background ratio due to the Majoron mass. The combination of constraints from astrophysics and laboratory experiments excludes a large range of neutrino-Majoron couplings in the mass range of intererest for Majoron dark matter.

The joint search for gravitational wave and low energy neutrino signals from core-collapse supernovae: methodology and status report

The detection of gravitational waves opens a new era in physics. Now it's possible to observe the Universe using a fundamentally new way. Gravitational waves potentially permit getting insight into the physics of Core-Collapse Supernovae (CCSNe). However, due to signi cant uncertainties on the theoretical models of gravitational wave emission associated with CCSNe, bene ts may come from multi-messenger observations of CCSNe. Such bene ts include increased con dence in detection, extending the astrophysical reach of the detectors and allowing deeper understanding of the nature of the phenomenon. Fortunately, CCSNe have a neutrino signature con rmed by the observation of SN1987A. The gravitational and neutrino signals propagate with the speed of light and without signi cant interaction with interstellar matter. So that they must reach an observer on the Earth almost simultaneously. These facts open a way to search for the correlation between the signals. However, this method is limited by the sensitivity of modern neutrino detectors that allow to observe CCSNe only in the Local Group of galaxies. The methodology and status of a proposed joint search for the correlation signals are presented here.

Supernova constraints on massive (pseudo)scalar coupling to neutrinos

In this paper we derive constraints on the emission of a massive (pseudo)scalar S from annihilation of neutrinos in the core of supernovae through the dimension-4 coupling νν S, as well as the effective dimension-5 operator 1/Λ(νν)(SS). While most of earlier studies have focused on massless or ultralight scalars, our analysis involves scalar with masses of order eV–GeV which can be copiously produced during {the explosion of supernovae, whose core temperature is} generally of order T∼ \U0001d4aaO(10) MeV. From the luminosity and deleptonization arguments regarding the observation of SN1987A, we exclude a large range of couplings 10−12 ≲ |gαβ|≲ 10−5 for the dimension-4 case, depending on the neutrino flavours involved and the scalar mass. In the case of dimension-5 operator, for a scalar mass from MeV to 100 MeV the coupling hαβ get constrained from 10−6 to 10−2, with the cutoff scale explicitly set Λ = 1 TeV. We finally show that if the neutrino burst of a nearby supernova explosion is detected by Super-Kamiokande and IceCube, the constraints will be largely reinforced.

Neutrino decays over cosmological distances and the implications for neutrino telescopes

We discuss decays of ultra-relativistic neutrinos over cosmological distances by solving the decay equation in terms of its redshift dependence. We demonstrate that there are significant conceptual differences compared to more simplified treatments of neutrino decay. For instance, the maximum distance the neutrinos have traveled is limited by the Hubble length, which means that the common belief that longer neutrino lifetimes can be probed by longer distances does not apply. As a consequence, the neutrino lifetime limit from supernova 1987A cannot be exceeded by high-energy astrophysical neutrinos. We discuss the implications for neutrino spectra and flavor ratios from gamma-ray bursts as one example of extragalactic sources, using up-to-date neutrino flux predictions. If the observation of SN 1987A implies that ν1 is stable and the other mass eigenstates decay with rates much smaller than their current bounds, the muon track rate can be substantially suppressed compared to the cascade rate in the region IceCube is most sensitive to. In this scenario, no gamma-ray burst neutrinos may be found using muon tracks even with the full scale experiment, whereas reliable information on high-energy astrophysical sources can only be obtained from cascade measurements. As another consequence, the recently observed two cascade event candidates at PeV energies will not be accompanied by corresponding muon tracks.

Nucleosynthesis of Light Elements and Heavyr‐Process Elements through the ν‐Process in Supernova Explosions

We study the nucleosynthesis of the light elements 7Li and 11B and the r-process elements in Type II supernovae from the point of view of supernova neutrinos and Galactic chemical evolution. We investigate the influence of the luminosity and average energy (temperature) of supernova neutrinos on these two nucleosynthesis processes. Common models of the neutrino luminosity, which is parameterized by the total energy Eν and decay time τν, and neutrino temperature are adopted to understand both processes. We adopt the model of the supernova explosion of a 16.2 M☉ star, which corresponds to SN 1987A, and calculate the nucleosynthesis of the light elements by postprocessing. We find that the ejected masses of 7Li and 11B are roughly proportional to the total neutrino energy and are weakly dependent on the decay time of the neutrino luminosity. As for the r-process nucleosynthesis, we adopt the same models of the neutrino luminosity in the neutrino-driven wind models of a 1.4 M☉ neutron star. We find that the r-process nucleosynthesis is affected through the peak neutrino luminosity, which depends on Eν/τν. The observed r-process abundance pattern is better reproduced at a low peak neutrino luminosity. We also discuss the unresolved problem of the overproduction of 11B in the Galactic chemical evolution of the light elements. We first identify that the ejected mass of 11B is a factor of 2.5-5.5 overproduced in Type II supernovae when one adopts neutrino parameters similar to those in previous studies, i.e., Eν = 3.0 × 1053 ergs, τν = 3 s, and a neutrino temperature T = T = 8.0 MeV/k. We have to assume Eν ≤ 1.2 × 1053 ergs to avoid the overproduction of 11B, which is too small to accept in comparison to the 3.0 × 1053 ergs deduced from the observation of SN 1987A. We here propose to reduce the temperatures of νμ,τ and μ,τ to 6.0 MeV/k in a model with Eν ~ 3.0 × 1053 ergs and τν ~ 9 s. This modification of the neutrino temperature is shown to resolve the overproduction problem of 11B while still keeping a successful r-process abundance pattern.

Supernova bounds on Majoron-emitting decays of light neutrinos

Neutrino masses arising from the spontaneous violation of ungauged lepton-number are accompanied by a physical Goldstone boson, generically called a Majoron. In the high-density supernova medium the effects of Majoron-emitting neutrino decays are important even if they are suppressed in vacuo by small neutrino masses and/or small off-diagonal couplings. We reconsider the influence of these decays on the neutrino signal of supernovae in the light of recent Super-Kamiokande data on solar and atmospheric neutrinos. We find that Majoron-neutrino coupling constants in the range $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}\ensuremath{\lesssim}g\ensuremath{\lesssim}2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ or $g\ensuremath{\gtrsim}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ are excluded by the observation of SN 1987A. Then we discuss the potential of Super-Kamiokande and the Sudbury Neutrino Observatory to detect Majoron-neutrino interactions in the case of a future galactic supernova. We find that these experiments could probe Majoron-neutrino interactions with improved sensitivity.

Are strange stars distinguishable from neutron stars by their cooling behaviour?

The general statement that strange stars cool more rapidly than neutron stars is investigated in greater detail. It is found that the direct Urca process could be forbidden not only in neutron stars but also in strange stars. If so, strange stars would be slowly cooling and their surface temperatures would be moreorless indistinguishable from those of slowly cooling neutron stars. The case of enhanced cooling is reinvestigated as well. It is found that strange stars cool significantly more rapidly than neutron stars within the first yr after birth. This feature could become particularly interesting if continued observation of SN 1987A would reveal the temperature of the possibly existing pulsar at its centre.

Differences in the Cooling Behavior of Strange Quark Matter Stars and Neutron Stars

The general statement that hypothetical strange quark matter stars cool more rapidly than neutron stars is investigated in greater detail. It is found that the direct Urca process can be forbidden not only in neutron stars, but also in strange-matter stars. In this case, strange-matter stars cool slowly and their surface temperatures are more or less indistinguishable from those of slowly cooling neutron stars. We investigate the case of enhanced cooling again. We find that strange-matter stars cool significantly more rapidly than neutron stars within the first ~30 yr after birth. This result may become particularly interesting if continued observation of SN 1987A reveals the temperature of the pulsar that may reside at its center.

The LAPEX experiment for observation of the supernova SN 1987A in hard X-rays

The LAPEX payload is described in the configuration that will be launched to observe the supernova SN 1987A. The balloon flight will be performed from Alice Springs (Australia) in April 1989 as a part of a NASA balloon campaign. The experiment will allow simultaneous observations of source and background in order to minimize systematic errors due to background variations. The limiting flux sensitivity of the instrument in the (20÷200) keV energy band is 4·10−6 ph/(cm2s keV) or ∼2.5 mCrab for a 104 s observation of SN 1987A. The presence of a57Co emission line in the SN 1987A photon spectrum could be detected down to an intensity level of ∼8·10−5 photons/cm2s as at 99.7% confidence level. The high resolution of the event timing (<0.1 ms) will make it possible to detect millisecond pulsations with amplitudes down to ∼4% of the expected average flux from SN 1987A in the (20÷60) keV band.

Correlation Analysis of the Data Recorded by the Baksan, Kamioka, and Mont Blanc Detectors during SN 1987A

Results are presented on the correlation analysis of data recorded by the Baksan, Kamioka, and Mont Blanc underground detectors during the explosion of the SN 1987. The analysis was performed in order to reinvestigate the observations of two burst of several pulses each occurring several hours before first optical observations. The Mont Blanc computer detected a burst of five pulses about 8 hrs before the first optical observation, followed by a second burst of three pulses about 2 hrs later; Kamioka and Baksan reported observations of a burst made by eleven and five pulses, respectively, delayed by 4.7 hrs in comparison with the Mont Blanc burst. The results of the analysis strongly suggest that the event was real, occurring a few hours before the first optical observation of SN 1987A. 9 refs.

An imaging observation of SN 1987A at gamma-ray energies

The Caltech imaging γ-ray telescope was launched by balloon from Alice Springs, NT, Australia for observations of SN 1987A during the period 1987 November 18.60-18.87 UT. The preliminary results presented here are derived from 8200 s of instrument live time on the supernova and 2500 s on the Crab Nebula and pulsar at a float altitude of 36 km. We have obtained the first images of the SN 1987A region at γ-ray energies confirming that the bulk of the γ-ray emission comes from the supernova and not from LMC X-1. We compare our flux measurements to recent predictions concerning the distribution of ^(56)Co in the supernova ejecta and find the data to be consistent with models invoking moderate mixing of core material into the envelope.

Observation of SN1987A by neutrino light

On the 54th day of 1987 an event occurred on Earth which gave reality to the fifty-five year old dreams of Baade, Zwicky, and Landauan event which confirmed thoughts of Chandrasekhar and Bethe. Also confirmed were the computer-based calculations of Colgate, Arnett, Burrows, Lattimer, Weaver, Woosley, Wilson and many others. The event was the arrival of a neutrino pulse that had been rushing towards the Earth for 170 000 yr. Had it arrived a few years earlier it would have gone unrecorded. Had its source in the Large Magellanic Cloud been much further away, it would have been too feeble to see. ~1016 neutrinos passed through the IMB detector (in the United States) in a few seconds. Only eight made recorded interactions. Simultaneously the Kamiokande detector (in Japan) recorded eleven. These numbers are in remarkable accord with the expectations of the above thinkers. It is a masterful triumph of the human intellect. Such pulses may pass our way every 10-100 years. *~ The chance that any more will be recorded may not be high since it requires the maintenance of large, complex detectors over these very long time periods. The detectors which recorded these events consisted of large masses of water viewed by many photomultiplier tubes located deep underground. **~ The events seen in the detectors are, individually, not very spectacular. In the IMB detector, for example, they have energies of only 20-40 MeV, close to that detector's threshold of visibility. An electron of 20 MeV will only light up approximately two dozen of the detector's 2048 phototubes. Such a signal must be picked out from a background due to radioactivity, electronic noise, and neutrino interactions from the atmospheric cosmic ray background. By appropriate filtering one can reduce the data to the cosmic ray neutrino rate, which is about two events per week in the 20-50 MeV energy band. A pulse of eight such events in six seconds is, therefore, truly extraordinary. This is what was recorded by IMB and similarly by a sequence of pulses in Kamiokande on February 23, many powers of ten above that expected from statistical fluctuations in the neutrino background.

X-Ray Observation of SN1987A from Ginga

AbstractAn unusual hard X-ray source was discovered in an error box of 0.2° × 0.3° including SN1987A from the X-ray astronomy satellite Ginga. The energy spectrum is quite unusual for any known classes of X-ray source, and apparently consists of two separate components, a soft component and a very hard component. This source is considered to be identified with SN1987A. The X-ray emergence occurred in July, 1987, or possibly even earlier. The soft component is significantly time-variable and also showed a flare-like increase in January, 1988, while the intensity of the hard component has remained relatively unchanged for more than 200 days.