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Free keywords:
General Relativity and Quantum Cosmology, gr-qc, Astrophysics, Instrumentation and Methods for Astrophysics, astro-ph.IM, Physics, Instrumentation and Detectors, physics.ins-det
Abstract:
Tilt-to-length (TTL) noise from angular jitter in LISA is projected to be the
dominant noise source in the milli-Hertz band unless corrected in
post-processing. The correction is only possible after removing the
overwhelming laser phase noise using time-delay interferometry (TDI). We
present here a frequency domain model that describes the effect of angular
motion of all three spacecraft on the interferometric signals after propagating
through TDI. We then apply a Fisher information matrix analysis to this model
to calculate the minimum uncertainty with which TTL coupling coefficients may
be estimated. Furthermore, we show the impact of these uncertainties on the
residual TTL noise in the gravitational wave readout channel, and compare it to
the impact of the angular witness sensors' readout noise. We show that the
residual TTL noise post-subtraction in the TDI variables for a case using the
LISA angular jitter requirement and integration time of one day is limited to
the 8\,pm/$\sqrt{\rm Hz}$ level by angular sensing noise. However, using a more
realistic model for the angular jitter we find that the TTL coupling
uncertainties are 70 times larger, and the noise subtraction is limited by
these uncertainties to the 14\,pm/$\sqrt{\rm Hz}$ level.
