AI Insight
This study investigates how massive scalar fields affect extreme mass-ratio inspirals (EMRIs), where a small object spirals into a supermassive black hole while emitting both gravitational waves and scalar radiation. The researchers found that massive scalar radiation produces measurable phase shifts in gravitational wave signals, with effects becoming stronger for highly eccentric orbits, and that heavier scalar fields suppress scalar emission because fewer wave harmonics can propagate to infinity. Using statistical methods, they demonstrate that the Laser Interferometer Space Antenna (LISA) could effectively constrain both the scalar charge of the inspiraling object and the mass of the scalar field.
Why it matters
This research provides a concrete method for testing alternative theories of gravity and detecting fundamental scalar fields using future space-based gravitational wave detectors. If scalar fields exist as predicted by some extensions to general relativity, LISA observations of EMRIs could reveal their properties and validate or constrain scalar-tensor theories of gravity.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
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Abstract: Extreme mass-ratio inspirals (EMRIs) are among the most promising sources for future space-based gravitational wave (GW) observatories and provide sensitive probes of additional fundamental fields in the strong-gravity regime. In the present work, we investigate eccentric equatorial EMRIs around Kerr black holes in the presence of a massive scalar field. We assume that the inspiralling object carries a scalar charge, therefore, emits scalar radiation in addition to GWs. By solving the massive scalar perturbation equation in the frequency domain, we compute the relativistic scalar energy fluxes at the event horizon and at infinity and incorporate them into an adiabatic inspiral model. We investigate the impact of the scalar charge and scalar field mass on the orbital evolution and gravitational waveforms by analysing the accumulated phase differences and waveform mismatches relative to both general relativity (GR) and the massless scalar limit. Our results show that the massive scalar radiation can produce significant GW dephasing, with the effect becoming increasingly pronounced for more eccentric orbits. In addition, the scalar flux is suppressed for larger scalar field masses as fewer scalar harmonics satisfy the propagation condition at infinity. Finally, using both Fisher-information-matrix forecasts and Bayesian parameter estimation, we assess the capability of the Laser Interferometer Space Antenna to constrain the scalar charge and scalar field mass. The two inference approaches gives consistent constraints, demonstrating that eccentric EMRIs provide a promising avenue for probing massive scalar fields and scalar-tensor extensions of gravity in the strong-field regime.