The Pair-Instability Window and the Remnant Mass Gap Implied by Metal-Free Progenitors

A sufficiently massive metal-free star develops a helium core so hot that photons convert into electron-positron pairs, removing pressure support and triggering a thermonuclear explosion that leaves no remnant at all. This study computes the relevant quantities from stated assumptions and compares them with published values. The headline results are: window low Msun = 140; window high Msun = 260; He low Msun = 58.8; He high Msun = 109.2; max energy 1e51 erg = 10.0; gap low Msun = 60; gap high Msun = 130. With the stated core fraction, initial masses near one hundred and forty to two hundred and sixty solar masses fall inside the explosive window, producing energies up to roughly ten times a normal supernova and leaving nothing behind. The study is simulated and computed, not measured, and its negative findings, where the computation does not support an effect, are reported at the same prominence as its positive ones.