Improved analysis of SN1987A antineutrino events
Abstract
We propose a new parameterization of the antineutrino flux from core collapse supernovae, that allows an interpretation of its astrophysical parameters within the Bethe and Wilson scenario for the explosion, and that leads to a reasonable (smooth) behavior of the average energy and of the luminosity curve. We apply it to analyze the events observed by KamiokandeII, IMB and Baksan detectors in correlation with SN1987A. For the first time, we consider in the same analysis all data characteristics: times, energies and angles of the observed events. We account for the presence of background and evaluate the impact of neutrino oscillations. The hypothesis that the initial luminous phase of emission (accretion) is absent can be rejected at the 2% significance level. Without the need to impose external priors in the likelihood analysis, the bestfit values of the astrophysical parameters are found to be in remarkable agreement with the expectations of the standard core collapse scenario; in particular, the electron antineutrinosphere radius is 16 km, the duration of the accretion phase is found to be 0.55 s, and the initial accreting mass is 0.22 M_{☉}. Similarly, the total energy emitted in neutrinos is 2.2×10^{53}erg, again close to the expectations. The errors on the parameters are evaluated and found to be relatively large, consistently with the limited number of detected events; the twodimensional confidence regions, that demonstrate the main correlations between the parameters, are also given.
 Publication:

Astroparticle Physics
 Pub Date:
 April 2009
 DOI:
 10.1016/j.astropartphys.2008.12.010
 arXiv:
 arXiv:0810.0466
 Bibcode:
 2009APh....31..163P
 Keywords:

 97.60.;
 26.30.Jk;
 95.55.Vj;
 14.60.Pq;
 Weak interaction and neutrino induced processes galactic radioactivity;
 Neutrino muon pion and other elementary particle detectors;
 cosmic ray detectors;
 Neutrino mass and mixing;
 Astrophysics
 EPrint:
 15 pages, 5 figures