Post-Newtonian expansions of extreme mass ratio inspirals of spinning bodies into Schwarzschild black holes

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Hauptverfasser: Skoupý, Viktor, Witzany, Vojtěch
Format: Preprint
Veröffentlicht: 2024
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author Skoupý, Viktor
Witzany, Vojtěch
author_facet Skoupý, Viktor
Witzany, Vojtěch
contents Space-based gravitational-wave detectors such as LISA are expected to detect inspirals of stellar-mass compact objects into massive black holes. Modeling such inspirals requires fully relativistic computations to achieve sufficient accuracy at leading order. However, subleading corrections such as the effects of the spin of the inspiraling compact object may potentially be treated in weak-field expansions such as the post-Newtonian (PN) approach. In this work, we calculate the PN expansion of eccentric orbits of spinning bodies around Schwarzschild black holes. Then we use the Teukolsky equation to compute the energy and angular momentum fluxes from these orbits up to the 5PN order. Some of these PN orders are exact in eccentricity, while others are expanded up to the tenth power in eccentricity. Then we use the fluxes to construct a hybrid inspiral model, where the leading part of the fluxes is calculated numerically in the fully relativistic regime, while the linear part in the small spin is analytically approximated using the PN series. We calculate LISA-relevant adiabatic inspirals and respective waveforms with this model and a fully relativistic model. Through the calculation of mismatch between the waveforms from both models we conclude that the PN approximation of the linear-in-spin part of the fluxes is sufficient for lower eccentricities.
format Preprint
id arxiv_https___arxiv_org_abs_2406_14291
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Post-Newtonian expansions of extreme mass ratio inspirals of spinning bodies into Schwarzschild black holes
Skoupý, Viktor
Witzany, Vojtěch
General Relativity and Quantum Cosmology
Instrumentation and Methods for Astrophysics
Space-based gravitational-wave detectors such as LISA are expected to detect inspirals of stellar-mass compact objects into massive black holes. Modeling such inspirals requires fully relativistic computations to achieve sufficient accuracy at leading order. However, subleading corrections such as the effects of the spin of the inspiraling compact object may potentially be treated in weak-field expansions such as the post-Newtonian (PN) approach. In this work, we calculate the PN expansion of eccentric orbits of spinning bodies around Schwarzschild black holes. Then we use the Teukolsky equation to compute the energy and angular momentum fluxes from these orbits up to the 5PN order. Some of these PN orders are exact in eccentricity, while others are expanded up to the tenth power in eccentricity. Then we use the fluxes to construct a hybrid inspiral model, where the leading part of the fluxes is calculated numerically in the fully relativistic regime, while the linear part in the small spin is analytically approximated using the PN series. We calculate LISA-relevant adiabatic inspirals and respective waveforms with this model and a fully relativistic model. Through the calculation of mismatch between the waveforms from both models we conclude that the PN approximation of the linear-in-spin part of the fluxes is sufficient for lower eccentricities.
title Post-Newtonian expansions of extreme mass ratio inspirals of spinning bodies into Schwarzschild black holes
topic General Relativity and Quantum Cosmology
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2406.14291