On the Detectability of a Stochastic Gravitational Wave Background from the White Dwarf Binaries in the LMC with LISA*

In the 2030s, the Laser Interferometer Space Antenna (LISA) will provide astronomers with the first tool to study gravitational waves (GWs) in the millihertz frequency range. In addition to individual binary sources, LISA will detect a stochastic GW foreground signal from the incoherent superposition of many double white dwarf (DWD) binary systems in the Milky Way. The detectability of similar backgrounds from nearby dwarf galaxies was unknown until this work. We evaluate the detectability of a stochastic GW background signal from the DWDs in the Large Magellanic Cloud (LMC). The LMC is an ideal first candidate due to its large size and close proximity relative to other dwarf galaxies. We use the Bayesian LISA Pipeline (BLIP) to simulate the stochastic GW signal and perform recovery and Bayesian parameter estimation in the spherical harmonic basis via nested sampling. We simulate the LMC signals from a DWD population using realistic population synthesis catalogs. While prospects for signal characterization must be studied further, initial results indicate that the LMC stochastic background will be detectable by LISA.