The SN 1987A Link to Gamma-Ray Bursts

Abstract

Early measurements of SN 1987A can be interpreted in light of the beam/jet (BJ) which had to hit polar ejecta (PE) to produce the “Mystery Spot” (MS), some 22 light‐days distant. It takes an extra eight days for the SN flash to hit the MS, and early measurements confirm 2×1039 ergs/s in the optical for a day at day 8, before dropping off by day 8.5. A linear ramp in luminosity starting near day 10 indicates particles from the BJ hitting the PE, with the fastest particles traveling at 0.8 c, and an upper hmit for the optical luminosity of the MS of 5×1040 ergs/s, about 23% of the total of 2.1×1041 ergs/s at day 20. The many details of SN 1987A strongly suggest that it resulted from a merger of two stellar cores of a common envelope (CE) binary, i.e. a “double degenerate” (DD)‐initiated SN. Without having to blast through the CE of Sk −69° 202, it is likely that the BJ would have caused a full, long‐soft gamma‐ray burst (ℓGRB) upon hitting the PE, thus DD is a mechanism which can produce ℓGRBs. A 0.5° offset, the typical collimation for a GRB, over the 22 light‐days from SN 1987A to its PE, produces ∼100 s of delay, matching the observed delay of the non‐prompt parts of ℓGRBs. Because DD must be the overwhelmingly dominant SN mechanism in elliptical galaxies, where only short, hard GRBs (sGRBs) have been observed, DD without CE or PE must also produce sGRBs, and thus the initial photon spectrum of 99% of all GRBs is known, and neutron star (NS)‐NS mergers may not make GRBs as we know them. Millisecond pulsars (MSPs) in the non‐core‐collapsed globular clusters are also 99% DD‐formed from white dwarf (WD)‐WD merger, consistent with their 2.10 ms minimum spin period, and the 2.14 ms signal seen from SN 1987A. The many observational details of la's strongly suggest that these are also DD. This is a concern for systematics in Ia Cosmology, because Type Ia SNe will appear to be Ic's when viewed from their DD merger poles, given sufficient matter above that lost to core‐collapse (otherwise it would just beg the question of what else they could possibly be, and other mechanisms, such as “delayed detonation” or “gravitationally confined detonation,” don't produce the inverse relation between polarization and luminosity). As a DD‐initiated SN, SN 1987A appears to be the Rosetta Stone for 99% of SNe, GRBs and MSPs, including all recent nearby SNe except SN 1986J, and the more distant SN 2006gy. There is no need to invent exotica to account for GRBs.