Detecting Cosmological Phase Transitions with Taiji: Sensitivity Analysis and Parameter Estimation

Abstract

We investigate the capability of the Taiji space-based gravitational wave observatory to detect stochastic gravitational wave backgrounds produced by first-order phase transitions in the early universe. Using a comprehensive simulation framework that incorporates realistic instrumental noise, galactic double white dwarf confusion noise, and extragalactic compact binary backgrounds, we systematically analyze Taiji's sensitivity across a range of signal parameters. Our Bayesian analysis demonstrates that Taiji can robustly detect and characterize phase transition signals with energy densities exceeding ${\Omega }_{\text{PT}}\gtrsim 1.4\times 10^{-11}$ across most of its frequency band, with particularly strong sensitivity around $10^{-3}$ to $10^{-2}$ Hz. For signals with amplitudes above ${\Omega }_{\text{PT}}\gtrsim 1.1\times 10^{-10}$, Taiji can determine the peak frequency with relative precision better than $10\%$. These detection capabilities would enable Taiji to probe electroweak-scale phase transitions in various beyond-Standard-Model scenarios, potentially revealing new physics connected to baryogenesis and dark matter production. We quantify detection confidence using both Bayes factors and the Deviance Information Criterion, finding consistent results that validate our statistical methodology.

23 pages, 8 figures; To be published in Chinese Physics C

References in corpus (2)

• Gravitational Waves from Phase Transitions at the Electroweak Scale and Beyond
• Confusion noise from Galactic binaries for Taiji

Cited by in corpus (4)

• Measuring gravitational wave spectrum from electroweak phase transition and Higgs self-couplings
• Bayesian analysis of the complex singlet model with phase transition gravitational waves
• Dynamical backreaction of a mass-acquiring scalar field on first-order phase transitions
• Inflationary phase transitions in the early Universe: A Bayesian study with space-based gravitational-wave detectors