Vacuum popcorn: could the Amaterasu particle come from a collapsing false-vacuum pocket?

Telescope Array’s 244 EeV Amaterasu particle of 2021 points back to a void with no expected source in it. I propose a sourcethat needs no host galaxy: pockets of false vacuum in the Galaxy’s own halo, left by a first-order phase transition, that trap a gasof particles light inside them and heavy outside. If such a pocket collapses today (a “pop”), its wall becomes ultra-relativisticand throws the trapped particles out, much as fingers pinched together shoot out a pip. I followed tens of thousands of themthrough such collapses with exact relativistic kinematics. A particle that meets the fast-moving wall with energy E leaves withabout m2out /4E, where mout is its mass outside. For a gas at rest and mass ratios up to a million, the median escapee carries 0.1to 1.6 per cent of m2out /min , and a particle of 107 GeV outside and 10 GeV inside has a median escape energy near 1020 eV.Their decays give photons and a few protons. The photon searches that found nothing still allow two to ten of Telescope Array’s28 events above 100 EeV, Amaterasu among them, to be pop protons, and a halo of pops would put 1.9 times as many of thatarray’s events in Amaterasu’s direction as sources spread evenly over the sky would. If the pockets are the dark matter, Auger’sphoton limit bounds their lifetime against popping at 6 × 1031 f s, where f is the share of a pocket’s energy that leaves as suchparticles. The nearest pops would arrive as several air showers at the same instant from one direction, which no experiment hasyet searched for at these energies.