Plasma noise in TianQin time-delay interferometry

Abstract

TianQin is a proposed geocentric space-based gravitational wave observatory mission, which requires time-delay interferometry (TDI) to cancel laser frequency noise. With high demands for precision, solar-wind plasma environment at ∼ 10 5 km above the Earth may constitute a nonnegligible noise source to laser interferometric measurements between satellites, as charged particles perturb the refractivity along light paths. In this paper, we first assess the plasma noises along single links from space-weather models and numerical orbits, and analyze the time and frequency domain characteristics. Particularly, to capture the plasma noise in the entire measurement band of 10 −4 − 1 Hz, we have performed additional space-weather magnetohydrodynamic simulations in finer spatial and temporal resolutions and utilized Kolmogorov spectra in high-frequency data generation. Then we evaluate the residual plasma noises of the first-and second-generation TDI combinations. Both analytical and numerical estimations have shown that under normal solar conditions the plasma noise after TDI is less than the secondary noise requirement. Moreover, TDI is shown to exhibit moderate suppression on the plasma noise below ∼ 10 −2 Hz due to noise correlation between different arms, when compared with the secondary noise before and after TDI.

Effect of Earth-Moon’s gravity on TianQin’s range acceleration noise. III. An analytical model

“…As in the previous case of static gravity, we calculate the inter-satellite range-acceleration ASD from Eq. (42). At the same time, we obtain the numerical result from TQPOP in which the force models consist of the Earth's static gravity and the gravity change from the free oscillations mentioned above.…”

“…We calculate the TianQin's rangeacceleration time series using the numerical procedure and the analytical formula, respectively. Then we process the data with a high-pass filter [42] to extract signals of Earth's free oscillation induced by earthquake above 10 −4 Hz. The numerical and analytical waveforms are compared in Fig.…”

The evaluation for plasma noise in arbitrary time-delay interferometry combinations

“…The result indicated that, the PSD of singlelink plasma noise based on the 572 daily measurements from Wind/SWE are lower than the single-link sensitivity requirements of LISA. In addition, in [16], the SWMF model and piecewise parabolic method with a Lagrangian remap-magnetohydrodynamic model were utilized to simulate plasma noise in the 10 −4 Hz-10 −1 Hz frequency band. It was demonstrated that plasma noise in this frequency band follows Kolmogorov spectrum.…”

“…It was demonstrated that plasma noise in this frequency band follows Kolmogorov spectrum. Currently, most research on plasma noise in space-based GW detectors relies on numerical results [13,14,16]. The numerical simulation results are more realistic but also require more computational resources and are limited by the resolution of models.…”

“…The numerical simulation results are more realistic but also require more computational resources and are limited by the resolution of models. In contrast, analytical results have shorter computation times and are convenient for subsequent data processing, and the feasibility of this analytical model has been demonstrated in [15,16]. In this paper, we primarily focus on the influence of time-delay interferometry (TDI) on plasma noise.…”