Post-Newtonian dynamics in dense star clusters: Binary black holes in the LISA band

The dynamical processing of black holes in the dense cores of globular clusters (GCs) makes them efficient factories for producing binary black holes (BBHs). Here we explore the population of BBHs that form dynamically in GCs and may be observable at mHz frequencies or higher with the future space-based gravitational-wave observatory LISA. We use our Monte Carlo stellar dynamics code, which includes gravitational radiation reaction effects for all BH encounters. By creating a representative local universe of GCs, we show that up to dozens of these systems may be resolvable by LISA. Approximately one-third of these binaries will have measurable eccentricities (e >10^-3 ) in the LISA band, and a small number (≲5 ) may evolve from the LISA band to the LIGO band during the LISA mission.