A. M. Rogan

Optimal statistic for detecting gravitational wave signals from binary inspirals with LISA

A binary compact object early in its inspiral phase will be picked up by its nearly monochromatic gravitational radiation by LISA. But even this innocuous appearing candidate poses interesting detection challenges. The data that will be scanned for such sources will be a set of three functions of LISAs twelve data streams obtained through time-delay interferometry, which is necessary to cancel the noise contributions from laser-frequency fluctuations and optical-bench motions to these data streams. We call these three functions pseudo-detectors. The sensitivity of any pseudo-detector to a given sky position is a function of LISAs orbital position. Moreover, at a given point in LISAs orbit, each pseudo-detector has a different sensitivity to the same sky position. In this work, we obtain the optimal statistic for detecting gravitational wave signals, such as from compact binaries early in their inspiral stage, in LISA data. We also present how the sensitivity of LISA, defined by this optimal statistic, varies as a function of sky position and LISAs orbital location. Finally, we show how a real-time search for inspiral signals can be implemented on the LISA data by constructing a bank of templates in the sky positions.

The optimal statistic for detecting eccentric binary compact objects with LISA

Eccentric binary compact objects have been predicted as LISA sources by several recent astrophysical studies. These objects are expected to radiate gravitational waves at twice the orbital frequency and at its harmonics. Indeed, for high enough eccentricity some harmonics will carry more power than the fundamental. This calls for a search statistic that combines power from the in‐band harmonics in an optimal way. Here, we present such a statistic for detecting these signals in LISA’s time‐delay‐interferometric observables.