Can theLaser Interferometer Space AntennaResolve the Distance to the Large Magellanic Cloud?

Abstract

The Laser Interferometer Space Antenna (LISA) is expected to detect N ~ 22 × 10±1 close white dwarf binaries in the Large Magellanic Cloud (LMC) through their gravitational radiation with signal-to-noise ratios greater than ~10 in observational durations of 3 yr or more. In addition to chirp mass, location on the sky, and other binary parameters, the distance to each binary is an independent parameter that can be extracted from an analysis of gravitational waves from these binaries. Using a sample of binaries, one can establish the mean distance to the LMC as well as the variance of this distance. Assuming no confusion noise at frequencies above 2 mHz, for data collected over 10 yr, LISA might determine the LMC distance to ~4.5(N/22)1/2(1 yr/Tobs)1/2% and the line-of-sight extent of the LMC to ~15(N/22)1/4%, relative to its distance, at the 1 σ confidence. For a 3 yr observational window, these estimates are degraded by a factor of ~2.5. In general, the estimates based on LISA are competitive with some of the proposed direct geometric techniques of measuring the LMC distance in the future with missions such as the Space Interferometry Mission and the Global Astrometric Interferometer for Astrophysics.