OBSERVATIONAL CONSTRAINTS ON THE MAXIMUM NEUTRON STAR MASS

摘要

We review estimates of the mass of the compact core in SN 1987A and conclude that the most accurate determination can be obtained from the known value of ～0.075 solar mass of Ni production in the explosion. With binding energy correction, this gives an upper limit of gravitational mass of ～1.56 solar mass, slightly larger than Brown & Bethe's previous estimate of ～1.5 solar mass. Observation by OSSE of the ratio of γ-rays from ~(57)Co and ~(56)Co indicates that neutron-rich material from the inner regions does not reach the mass cut by convection or Rayleigh-Taylor instability. Arguments that the core of SN 1987A went into a black hole are reviewed. If one accepts this to be true, then the maximum compact core mass gives an upper limit on neutron star masses of (M_(NS))_(max) ≈ 1.56 solar mass (gravitational), in rough agreement with the previous result of Brown & Bethe.