Supernova 1987A: 3D Mixing and light curves for explosion models based on binary-merger progenitors

Abstract

Six binary-merger progenitors of Supernova 1987A (SN 1987A), whose properties are close to those of the blue supergiant Sanduleak −69 • 202, are exploded by neutrino heating in three-dimensions (3D), and light-curve calculations are performed in spherical symmetry, starting long after shock breakout. Our results confirm basic findings of previous works using single-star progenitors: (1) 3D neutrino-driven explosions with SN 1987Alike energies synthesize an amount of 56 Ni that is consistent with the radioactive tail of the light curve; (2) hydrodynamic models mix hydrogen inward to minimum velocities below 40 km s −1 as required by spectral observations of SN 1987A; and (3) for given explosion energy the efficiency of outward radioactive 56 Ni 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 consistent with 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. The light curve shape of models that mix about 0.5 M of hydrogen into the helium shell and that exhibit strong outward mixing of 56 Ni with maximum velocities exceeding the 3000 km s −1 observed for the bulk of ejected 56 Ni is in very good agreement with the dome of the SN 1987A light curve. A comparative analysis of light-curve models of SN 1987A based on 3D neutrino-driven explosions of single-star and binary-merger progenitors shows that only one binary model matches all observational constraints with one exception.

Supernova Fallback as Origin of Neutron Star Spins and Spin-kick Alignment

“…Since the present paper is not focussed on the numerical modeling and simulation results, but these results are only taken as a motivation for proposing the revised fallback scenario described in Section 3, we refrain from repeating a detailed description of the code and its inputs here. All relevant information can be found in previous papers of some of the authors (Wongwathanarat et al 2013(Wongwathanarat et al , 2015(Wongwathanarat et al , 2017Utrobin et al 2015Utrobin et al , 2017Utrobin et al , 2019Utrobin et al , 2021 and in Wongwathanarat & Janka (in preparation).…”

The morphology of the ejecta of SN 1987A at 31 years from 1150 to 10000 Å

“…This corresponds to the region with enriched Mg abundance and high density from the O/Ne/Mg core. Note that this ejecta model is a result of a spherical av-10 10 10 8 10 6 10 4 10 2 10 0 F( 1240 erage with clumps from the O/Ne/Mg core mixed with H and He rich gas (Utrobin et al 2021). Therefore, clumps from the core will have considerably higher optical depths within this region and may also be optically thick at higher velocities.…”

“…X-ray deposition in the ejecta was discussed in Fransson et al (2013), based on the 14E1 model in Blinnikov et al (2000). We update this with the M15-7b merger model from Utrobin et al (2021), which gives the best agreement with the light curve of SN 1987A. This model is based on a 15 + 7 M merger model from Menon & Heger (2017), which was exploded in 3D and then mapped into a 1D model by taking spherical averages of the density and abundances.…”

“…Based on the velocities of matter in the rings, they were ejected around 20000 years ago , probably after the merger of a binary system with masses on the order of 15 M and 5 M , before which the primary was a red supergiant (RSG) star (Morris & Podsiadlowski 2007. Utrobin et al (2021) found a numerical SN model of such a merger remnant progenitor (with initial masses of 15 M and 7 M , based on Menon & Heger 2017) a better match to the observables of SN 1987A than single-star models. Orlando et al (2020) and Ono et al (2020) performed extensive magnetohydrodynamic modelling and found a similar merger scenario (14 M + 9 M ; Urushibata et al 2018) to match the observed properties of the BSG progenitor, the SN itself and the evolution of its remnant.…”