Theoretical frameworks for multi-messenger gravitational wave astrophysics: advanced waveform modeling and parameter estimation for space-based detection systems Gravitational waves

Abstract

The Laser Interferometer Space Antenna (LISA), formally adopted by the European Space Agency in January 2024 with a planned 2035 launch, will revolutionize gravitational wave astronomy by accessing the millihertz frequency band. This theoretical framework is developed for multi-messenger gravitational wave astrophysics that employ 3.5PN-accurate inspiral waveforms with leading self-force corrections, numerical relativity-calibrated merger-ringdown models, and reduced-order modeling for computational efficiency. Using the Nessai nested sampling algorithm with LISA's 2.5-Gm arm configuration and design sensitivity curve, this study demonstrates median sky-localization improvements from 120 deg² to 35 deg² for massive black hole binaries at SNR 15-50, with luminosity-distance uncertainties reduced by 24% compared to standard methods. For extreme mass-ratio inspirals, This achieve < 1% mass ratio recovery accuracy at  using augmented analytic kludge waveforms. This global fitting framework successfully resolves 94% of injected sources in confusion-limited regimes. These results assume circular or low-eccentricity orbits (e<0.1), neglect subdominant spin-orbit coupling effects beyond 3.5PN order, treat detector noise as stationary Gaussian, and do not account for thermal noise systematics. The frameworks enable reliable parameter estimation for multi-messenger observations, with joint gravitational wave and electromagnetic analysis constraining the Hubble constant to 3-5% precision for sources at z<2, contingent on electromagnetic counterpart identification within 30 deg² sky areas.