Probing near-zone magnetic fields with extreme mass-ratio inspirals
Abstract
We investigate whether weak near-zone magnetic fields can leave observable imprints on extreme-mass-ratio inspiral (EMRI) waveforms. The central massive black hole is modeled by the magnetized Schwarzschild, or Ernst, solution, and the secondary compact object is treated as a neutral point particle on equatorial circular geodesics. We compute the magnetic corrections to the circular-orbit quantities and the innermost stable circular orbit, and then evolve the inspiral using a hybrid, source-corrected Regge--Wheeler--Zerilli approximation, in which the Schwarzschild wave-propagation potentials are kept fixed while the source is evaluated on the magnetized orbit. For a fiducial system with M=106M⊙ and μ=10M⊙, a field strength B≃ 4×10−5M−1, corresponding to Bphys∼109 G, produces a one-year dephasing of about 1.3 rad and \ccr{a LISA-noise-weighted mismatch which, after maximization over the relative arrival time and initial GW phase, remains slightly above the adopted distinguishability threshold at one year}. Our results suggest that EMRIs can in principle probe extremely strong near-zone magnetic fields, whereas ordinary magnetic environments around massive black holes are likely too weak to produce detectable effects within the present approximation.
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BibTeX
@misc{hu2026probing,
title = {{Probing near-zone magnetic fields with extreme mass-ratio inspirals}},
author = {Jin-Lu Hu and Xin-Dong Du and Peng-Cheng Li and Tieguang Zi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.05909},
eprint = {2607.05909},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.05909},
}
RIS
TY - UNPB
TI - Probing near-zone magnetic fields with extreme mass-ratio inspirals
AU - Jin-Lu Hu
AU - Xin-Dong Du
AU - Peng-Cheng Li
AU - Tieguang Zi
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2607.05909
UR - https://arxiv.org/abs/2607.05909
AB - We investigate whether weak near-zone magnetic fields can leave observable imprints on extreme-mass-ratio inspiral (EMRI) waveforms. The central massive black hole is modeled by the magnetized Schwarzschild, or Ernst, solution, and the secondary compact object is treated as a neutral point particle on equatorial circular geodesics. We compute the magnetic corrections to the circular-orbit quantities and the innermost stable circular orbit, and then evolve the inspiral using a hybrid, source-corrected Regge--Wheeler--Zerilli approximation, in which the Schwarzschild wave-propagation potentials are kept fixed while the source is evaluated on the magnetized orbit. For a fiducial system with M=10^6M_⊙ and μ=10M_⊙, a field strength B≃ 4×10^−5M^−1, corresponding to B_phys∼10^9 G, produces a one-year dephasing of about 1.3 rad and \ccr{a LISA-noise-weighted mismatch which, after maximization over the relative arrival time and initial GW phase, remains slightly above the adopted distinguishability threshold at one year}. Our results suggest that EMRIs can in principle probe extremely strong near-zone magnetic fields, whereas ordinary magnetic environments around massive black holes are likely too weak to produce detectable effects within the present approximation.
ER -