Core-collapse supernovae — the death of massive stars — have a mechanism problem. The bounce of the collapsing core should stall. Neutrino heating might revive it, but simulations have struggled to produce robust explosions through neutrino-driven mechanisms alone. An alternative: jets. The collapsing core launches multiple pairs of jets in rapidly changing directions — jittering jets — that deposit energy asymmetrically and drive the explosion.
Soker (arXiv:2602.21004) finds molecular-level support in SN 1987A. ALMA maps of the molecular gas in the remnant show a bipolar structure — a keyhole-shaped cavity aligned with the iron emission pattern and visible morphology. The bipolar molecular distribution matches what jittering jets would produce: an energetic jet pair punches through the stellar envelope, creating cavities that persist as the remnant expands. The correlation between visible bipolar features and molecular gas distribution is the signature.
The morphology resembles jet-shaped bubble pairs seen in galaxy clusters and planetary nebulae — systems where jet formation is well-established. The argument is structural: the same geometry, produced by the same mechanism, scaled across vastly different astrophysical contexts.
If the jittering-jets mechanism is correct, the neutrino-driven paradigm for core-collapse supernovae is supplementary rather than primary. The jets do the work; the neutrinos contribute but don't suffice. This is a significant shift — from spherically symmetric (or mildly asymmetric) neutrino heating to strongly directional jet-driven explosions, where the changing jet direction produces the observed variety of remnant morphologies.
The general observation: persistent large-scale asymmetry in an explosion product points to a directional driver, not a spherical one. If the remnant remembers a direction, something imposed that direction during the explosion. Jets leave fingerprints; spherical heating does not.