Probing parity-breaking black-hole geometry with extreme-mass-ratio inspirals
Abstract
We investigate the gravitational-wave signatures of equatorial reflection symmetry breaking in extreme-mass-ratio inspirals (EMRIs) around a parity-violating conformal Kerr black hole. For the circular-orbit branch connected to equatorial Kerr orbits, we derive the dynamics through second order in the dimensionless deformation parameter ε and construct adiabatic inspirals and gravitational-wave signals using a mass-quadrupole prescription. Equatorial reflection maps ε to −ε, making the polar displacement odd and the orbital frequency and energy even in the deformation. The induced first harmonic has a small direct contribution for the configurations studied, while second-order dynamical corrections accumulate over many cycles to produce appreciable dephasing. We find that rapid black-hole rotation enhances these phase effects and the associated noise-weighted waveform mismatch. For a one-year inspiral of a 10M⊙ object into a 106M⊙ black hole with a/M=0.9 and viewing inclination ι=2π/3, the fixed-parameter mismatch reaches the comparison benchmark ℳ=0.01 at approximately ε=10−3, without optimization over time, phase, or Kerr parameters. A single-parameter Fisher analysis also indicates improved local sensitivity to ε at high spin. These results connect the reflection properties of the circular branch to accumulated source-phase effects and complement tests of propagation birefringence. The sensitivity estimates remain conditional on the adiabatic quadrupole model and the adopted comparison procedure; robust observational constraints require more accurate radiation modeling and a full parameter-estimation analysis.
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BibTeX
@misc{wu2026probing,
title = {{Probing parity-breaking black-hole geometry with extreme-mass-ratio inspirals}},
author = {Zhen-Bo Wu and Qing Ou and Peng-Cheng Li},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.25291},
eprint = {2610.25291},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.25291},
}
RIS
TY - UNPB
TI - Probing parity-breaking black-hole geometry with extreme-mass-ratio inspirals
AU - Zhen-Bo Wu
AU - Qing Ou
AU - Peng-Cheng Li
PY - 2026
DA - 2026/10/18
PB - arXiv
DO - 10.48550/arxiv.2610.25291
UR - https://arxiv.org/abs/2610.25291
AB - We investigate the gravitational-wave signatures of equatorial reflection symmetry breaking in extreme-mass-ratio inspirals (EMRIs) around a parity-violating conformal Kerr black hole. For the circular-orbit branch connected to equatorial Kerr orbits, we derive the dynamics through second order in the dimensionless deformation parameter ε and construct adiabatic inspirals and gravitational-wave signals using a mass-quadrupole prescription. Equatorial reflection maps ε to −ε, making the polar displacement odd and the orbital frequency and energy even in the deformation. The induced first harmonic has a small direct contribution for the configurations studied, while second-order dynamical corrections accumulate over many cycles to produce appreciable dephasing. We find that rapid black-hole rotation enhances these phase effects and the associated noise-weighted waveform mismatch. For a one-year inspiral of a 10M_⊙ object into a 10^6M_⊙ black hole with a/M=0.9 and viewing inclination ι=2π/3, the fixed-parameter mismatch reaches the comparison benchmark ℳ=0.01 at approximately ε=10^−3, without optimization over time, phase, or Kerr parameters. A single-parameter Fisher analysis also indicates improved local sensitivity to ε at high spin. These results connect the reflection properties of the circular branch to accumulated source-phase effects and complement tests of propagation birefringence. The sensitivity estimates remain conditional on the adiabatic quadrupole model and the adopted comparison procedure; robust observational constraints require more accurate radiation modeling and a full parameter-estimation analysis.
ER -