Descalarization bursts from Galactic supramassive neutron stars: a kHz continuous-wave target

In massive scalar-tensor gravity, a scalarized neutron star must shed its scalar hair as it collapses into a black hole. Using 3D simulations of a realistic rotating progenitor we show that dispersion stretches the emitted burst into a quasi-monochromatic signal in the kHz frequency range lasting $>{10}^4$ yr and amenable to continuous-wave methods. We find that detecting these signals in directed searches of supernova remnants without a central pulsar requires sensitivity depths of 233–762 $\mathrm{H}{\mathrm{z}}^{-1\mathrm{/}2}$ with the A±ET-CE detector network. We estimate up to $\sim 3$ of these signals in transit at any observational epoch.