Consequences of Disk Scale Height onLISAConfusion Noise from Close White Dwarf Binaries

Gravitational radiation from the Galactic population of close white dwarfbinaries (CWDBs) is expected to produce a confusion-limited signal at the lowerend of the sensitivity band of the Laser Interferometer Space Antenna (LISA).The canonical scale height of the disk population has been taken to be 90 pcfor most studies of the nature of this confusion-limited signal. This estimateis probably too low, and the consequences of a more realistic scale height areinvestigated with a model of the LISA signal due to populations of close whitedwarf binaries with different scale heights. If the local space density ofCWDBs is held constant, increasing the scale height results in both an increasein the overall strength of the confusion-limited signal as well as in increasein the frequency at which the signals become individually resolvable. If thetotal number of binaries is held constant, increasing the scale height resultsin a reduction of the number of expected bright signals above theconfusion-limited signal at low frequencies. We introduce an estimator forcomparing this transition frequency that takes into account the signalspreading at higher frequencies.Comment: 28 pages, 7 figures, accepted by Astrophysical Journal, substantial revisions in response to referee, conclusions slightly revise