Transmuted Gravity Wave Signals from Primordial Black Holes

Abstract

Primordial black holes (PBHs) interacting with compact stars in binaries lead to a new class of gravity wave signatures that we explore. A small $10^{-16} - 10^{-7} M_{\odot}$ PBH captured by a neutron star or a white dwarf will eventually consume the host. The resulting black hole will have a mass of only $\sim0.5-2.5 M_{\odot}$, not expected from astrophysics. For a double neutron star binary system this leads to a transmutation into a black hole-neutron star binary, with a gravity wave signal detectable by the LIGO-VIRGO network. For a neutron star-white dwarf system this leads to a black hole-white dwarf binary, with a gravity wave signal detectable by LISA. Other systems, such as cataclysmic variable binaries, can also undergo transmutations. We describe gravity wave signals of the transmuted systems, stressing the differences and similarities with the original binaries. New correlating astrophysical phenomena, such as a double kilonova, can further help to distinguish these events. This setup evades constraints on solar mass PBHs and still allows for PBHs to constitute all of the dark matter. A lack of signal in future searches could constrain PBH parameter space.