Supernova 1987A: 3D Mixing and Light Curves for Explosion Models Based on Binary-merger Progenitors

Six binary-merger progenitors of supernova 1987A (SN 1987A) with properties close to those of the blue supergiant Sanduleak -69°202 are exploded by neutrino heating and evolved until long after shock breakout in 3D and continued for light-curve calculations in spherical symmetry. Our results confirm previous findings for single-star progenitors: (1) 3D neutrino-driven explosions with SN 1987A-like energies synthesize ⁵⁶Ni masses consistent with the radioactive light-curve tail; (2) hydrodynamic models mix hydrogen inward to minimum velocities below 40 km s^-1 compatible with spectral observations of SN 1987A; and (3) for given explosion energy the efficiency of outward radioactive ⁵⁶Ni mixing depends mainly on high growth factors of Rayleigh-Taylor instabilities at the (C+O)/He and He/H composition interfaces and a weak interaction of fast plumes with the reverse shock occurring below the He/H interface. All binary-merger models possess presupernova radii matching the photometric radius of Sanduleak -69°202 and a structure of the outer layers allowing them to reproduce the observed initial luminosity peak in the first ~7 days. Models that mix about 0.5 M_⊙ of hydrogen into the He-shell and exhibit strong outward mixing of ⁵⁶Ni with maximum velocities exceeding the 3000 km s^-1 observed for the bulk of ejected ⁵⁶Ni have light-curve shapes in good agreement with the dome of the SN 1987A light curve. A comparative analysis of the best representatives of our 3D neutrino-driven explosion models of SN 1987A based on single-star and binary-merger progenitors reveals that only one binary model fulfills all observational constraints, except one.