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arXiv · 2609.37039

Beyond circular and equatorial orbits: Bayesian constraint on vector charge with the adiabatic inspirals of generic Kerr geodesics

Tieguang Zi·Genliang Li
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Abstract

Extreme-mass-ratio inspirals (EMRIs) offer a powerful probe of additional fundamental fields through their cumulative influence on gravitational-wave phases. However, modeling vector radiation from generic Kerr orbits requires the evolution of the Carter constant, which cannot be determined from energy and angular-momentum balance alone. Here we derive the orbit-averaged electromagnetic Carter-constant flux for eccentric and inclined, nonresonant Kerr geodesics, including sections at infinity and event horizon. Combining the gravitational and electromagnetic energy and angular-momentum fluxes, we construct generic adiabatic inspirals using a four-dimensional Chebyshev interpolation mathod. We incorporate the relativistic trajectories into the state of the art of FastEMRIWaveform package and perform Bayesian inference of vector charge carried by secondaries. Our analysis reveals substantial correlations between the charge and intrinsic source parameters, with vector charge constraints exhibiting a nonmonotonic dependence on orbital inclination. These results establish a framework for investigating additional vector-radiation channels in generic EMRIs and their implications for tests of gravity with future space-based gravitational wave observations.

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Tieguang Zi, Genliang Li. 2026-09-29. Beyond circular and equatorial orbits: Bayesian constraint on vector charge with the adiabatic inspirals of generic Kerr geodesics. https://arxiv.org/abs/2609.37039

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