New physics from supernova 1987A

Abstract

An overview of the significance for physics of the closest visual supernova in 400 years is presented. The supernova occurred in the Large Magellanic Cloud (LMC), ∼50 kpc away. The supernova star was a massive star of ∼20 M °, but it was blue, not red. It is explained how it is quite reasonable for such a star to explode and the nucleosynthesis contributions of the ejecta are described. The expectations and comparison with observations for the light curve are discussed. In particular the lower than standard luminosity and higher velocities are a natural consequence of the pre-supernova star being a blue rather than red (super)giant. The observations of the characteristic γ-ray lines for 56Co decay proves that significant heavy element synthesis occured. The expectations for the remnant and its possible associated particle acceleration are discussed. Of particular importance to physicists is the confirmed detection of neutrinos from the event by detectors in the United States and Japan, with possible detections in Italy and the Soviet Union as well. Not only did this establish extra solar system neutrino astronomy, but it also served to confirm the general picture of stellar collapse and to constrain the properties of neutrinos. Some model-independent constraints on neutrino properties are presented, as well as those conclusions which are more dependent on the details of the supernova model. It is shown that the well established Kamioka-IMB neutrino burst experimentally implies an event with about 2 to 4 × 10 53 erg emitted in neutrinos and a temperature, T v e , of between 4 and 4.5 MeV. This event is in excellent agreement with what one would expect from the gravitational core collapse of a massive star, when the effects of neutral currents are included. Detailed collapse models with timescales of seconds and high energy tails above thermal are marginally favored. A neutrino detection such as that reported earlier in Mt. Blanc would require more than the rest mass energy of a neutron star to be converted to neutrinos if it were to have its origin in the LMC. Thus it is probably unrelated to the supernova. The anticipated frequency of collapse events in our Galaxy as implied by SN 1987A is also discussed, with a rate as high as 1 10 year shown to be not unreasonable. This review also briefly discusses the erroneous report of a 0.5 ms pulsar and potential nuclear equation of state implications of pulsars.