Speaker
Description
We investigate the detectability of line-of-sight acceleration (LOSA) in gravitational-wave signals from massive binary black holes (MBHBs) observable by LISA. A constant LOSA introduces a $-4$PN correction to the inspiral phase, which we derive and implement in the \texttt{LISAbeta} analysis pipeline.
Our Bayesian analysis reveals that LOSA measurement precision depends strongly on total mass and observation duration. Lower-mass systems ($10^4$--$10^5\,M_\odot$) benefit from extended low-frequency inspiral, with uncertainty decreasing steadily as more pre-merger data are included. High-mass systems ($10^7\,M_\odot$) are insensitive to early inspiral data, as most signal-to-noise accumulates in the final months.
Neglecting a genuine LOSA induces severe systematic biases in chirp mass and mass ratio. We validate the constant-acceleration approximation against time-varying jerk, and map the detectability of third-body perturbers ($\gtrsim 10^8\,M_\odot$) out to $\sim 1\,$pc, establishing LOSA as a novel probe of MBHB environments.