SN1987A supernova: a black-hole precursor?

Abstract

The 11 + 8 neutrino events observed at Kamiokande1 and IMB2 detectors have been analysed by several authors1–12. The inferred total neutrino luminosity Wv and its distribution among the various neutrino species, vary between the different analyses depending on the events included in the analysis, the parameterization of the neutrino spectra, the role played by ve–oxygen scattering, the distance of the Large Magellanic Cloud (LMC) and other aspects. Most authors find high total neutrino energy, in the range Wv = 3–6.7×1053 erg, and a large flux of prompt neutronization neutrinos ≈1010cm−2. The Kamiokande collaboration1 has quoted a value of = 8×1052 erg for the total ve energy. This value is subject to uncertainties in the distance to the LMC, low statistics and other experimental and theoretical factors. From this value we have deduced8 that Wv≈6.7×1053 erg which implies a gravitational energy release ≳0.37 M⊙c2. This value is too high for a binding energy of a standard, 1.4 M⊙, neutron star which means that a massive M≳2 M⊙ neutron star or a black hole form. In the following we focus on lepton number conservation and the ensuing limitation on . We show that an identification of the first two events in the Kamiokande data as ve prompt events requires a mass, M≳6 M⊙, which implies a black-hole formation. This is also consistent with the probable identification of the progenitor13 as a B3I supergiant of ∼25M⊙.