Effect of noise characterization on the detection of mHz stochastic gravitational waves

TL;DR

This paper investigates how detailed noise modeling affects the ability of LISA to detect millihertz stochastic gravitational waves, emphasizing the importance of realistic noise simulations and flexible inference models.

Contribution

It advances previous noise inference methods by incorporating more realistic instrumental simulations and additional noise modeling degrees of freedom for LISA.

Findings

Refined detection bounds depend on noise model flexibility.

Separate transfer functions improve noise characterization accuracy.

Enhanced noise modeling increases robustness of SGWB detection.

Abstract

Pulsar timing arrays' hint for a stochastic gravitational-wave background (SGWB) leverages the expectations of a future detection in the millihertz band, particularly with the LISA space mission. However, finding an SGWB with a single orbiting detector is challenging: It calls for cautious modelling of instrumental noise, which is also mainly stochastic. It was shown that agnostic noise reconstruction methods provide robustness in the detection process. We build on previous work to include more realistic instrumental simulations and additional degrees of freedom in the noise inference model and analyze the impact of LISA's sensitivity to SGWBs. Particularly, we model the two main types of noise sources with separate transfer functions and power spectral density spline fitting. We assess the detectability bounds and their dependence on the flexibility of the noise model and on the prior probability, allowing us to refine previously reported results.