Synthetic Lisa: Simulating Time Delay Interferometry in a Model Lisa

Synthetic LISA, developed at the Jet Propulsion Laboratory, is a C++/Python package to simulate the LISA science process at the level of scientific and technical requirements. It generates synthetic time series of the LISA fundamental noises, as filtered through all the Time-Delay-Interferometric (TDI) observables; it provides a streamlined module to compute the TDI responses to gravitational waves, according to a full model of TDI (including the motion of the LISA array, and the temporal and directional dependence of the armlengths). Synthetic LISA is written as a C++ modular package that allows adding code for specific gravitational-wave sources, or for new noise models; time series for waves and noises can also be easily loaded from disk or memory. In this paper we describe the theoretical model that underlies Synthetic LISA, we discuss the implementation of the package, we test its correctness, and we show examples of its use in characterizing the laser-noise residuals left by first-generation TDI with realistic time-dependent armlengths, and in estimating the armlengthmeasurements error budgets required for effective laser-noise cancellation in both firstand secondgeneration TDI. Subject headings: gravitation — gravitational waves — instrumentation: interferometers — space vehicles