The Impact of Spin Priors on Parameterized Tests of General Relativity
Abstract
Spin priors play a fundamental role in gravitational-wave parameter estimation, yet their impact on parameterized tests of General Relativity (GR) remains insufficiently understood. We systematically investigate how spin-prior choices affect the 1.5PN deviation parameter δϕ̂3 using real gravitational-wave events. Prior-induced effects are quantified through the Jensen--Shannon divergence and posterior median shifts. We find that χp is significantly more sensitive to the spin prior than χeff, while δϕ̂3 is generally robust but can exhibit larger shifts in low-information regimes. GW231123_135430 shows particularly strong sensitivity, but its inferred properties are subject to waveform-model and event-specific systematics, warranting caution in interpreting results strongly influenced by this event. When δϕ̂3 is included in the parameter-estimation model, a strong correlation emerges between the prior sensitivities of χeff and δϕ̂3, consistent with their partial degeneracy at the 1.5PN order, whereas χp remains weakly correlated. A leave-one-out test shows that GW231123\_135430 significantly affects the correlation strength, but the correlation persists when this event is removed. These results demonstrate that spin-prior choices can propagate into parameterized tests of GR and should be carefully accounted for when interpreting apparent deviations from GR.
Versions
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BibTeX
@misc{wu2026impact,
title = {{The Impact of Spin Priors on Parameterized Tests of General Relativity}},
author = {Tian-Hao Wu and Shu-Jun Rong},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.04579},
eprint = {2605.04579},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.04579},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - The Impact of Spin Priors on Parameterized Tests of General Relativity
AU - Tian-Hao Wu
AU - Shu-Jun Rong
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2605.04579
UR - https://arxiv.org/abs/2605.04579
AB - Spin priors play a fundamental role in gravitational-wave parameter estimation, yet their impact on parameterized tests of General Relativity (GR) remains insufficiently understood. We systematically investigate how spin-prior choices affect the 1.5PN deviation parameter δϕ̂_3 using real gravitational-wave events. Prior-induced effects are quantified through the Jensen--Shannon divergence and posterior median shifts. We find that χ_p is significantly more sensitive to the spin prior than χ_eff, while δϕ̂_3 is generally robust but can exhibit larger shifts in low-information regimes. GW231123_135430 shows particularly strong sensitivity, but its inferred properties are subject to waveform-model and event-specific systematics, warranting caution in interpreting results strongly influenced by this event. When δϕ̂_3 is included in the parameter-estimation model, a strong correlation emerges between the prior sensitivities of χ_eff and δϕ̂_3, consistent with their partial degeneracy at the 1.5PN order, whereas χ_p remains weakly correlated. A leave-one-out test shows that GW231123\_135430 significantly affects the correlation strength, but the correlation persists when this event is removed. These results demonstrate that spin-prior choices can propagate into parameterized tests of GR and should be carefully accounted for when interpreting apparent deviations from GR.
ER -