Impact of LISA's low frequency sensitivity on observations of massive black hole mergers

LISA will be able to detect gravitational waves from inspiralling massive black hole (MBH) binaries out to redshifts z > 10. If the binary masses and luminosity distances can be extracted from the LISA data stream, this information can be used to reveal the merger history of MBH binaries and their host galaxies in the evolving universe. Since this parameter extraction generally requires that LISA observe the inspiral for a significant fraction of its yearly orbit, carrying out this program requires adequate sensitivity at low frequencies, f < 10^{-4} Hz. Using several candidate low frequency sensitivities, we examine LISA's potential for characterizing MBH binary coalescences at redshifts z > 1.