Spatial and Spectral Characterization of the Gravitational-wave Background with the PTA Optimal Statistic

• DOI: 10.48550/arxiv.2406.11954
• Publication Date: 2024-06-17
• Authors: Kyle A. Gersbach; Stephen R. Taylor; P. M. Meyers; Joseph D. Romano
• Keywords: Statistic; Characterization

Pulsar timing arrays (PTAs) have made tremendous progress and are now showing strong evidence for the gravitational-wave background (GWB). Further probing origin characteristics of GWB will require more generalized analysis techniques. Bayesian methods most often used but can be computationally expensive. On other hand, frequentist methods, like PTA Optimal Statistic (OS), efficient produce results that complementary to allowing stronger statistical cases built from a confluence different approaches. In this work we expand capabilities OS through technique call Per-Frequency (PFOS). The PFOS removes underlying power-law assumption inherent in previous implementations OS, allows one estimate spectrum frequency-by-frequency manner. We also adapted recent generalization pipeline into PFOS, making it capable accurately characterizing intermediate GW signal regimes using only small fraction necessary computational resources when compared with fully-correlated while empowering many new types analyses not possible before. find even regime, where dominates over noise all frequencies, injected value lies within 50th-percentile uncertainty distribution 41-45% simulations, remaining 3$\sigma$-consistent unbiased estimation.