Testing charged bumblebee black holes through high-frequency quasi-periodic oscillations in X-ray binaries

Abstract

We investigate strong-field orbital dynamics for static spherically symmetric charged bumblebee black holes featuring spontaneous Lorentz-violating effects. Analysis of null and timelike circular geodesics yields the photon-sphere radius, the innermost stable circular orbit (ISCO) radius, and characteristic orbital frequencies for test particles. Within the relativistic precession model for high-frequency quasi-periodic oscillations (HFQPOs), observed twin-peak frequencies are governed by the full set of fundamental parameters $M$, $X=r/M$, $l_1$, $l_2$, and $Q_0/M$. Among them, $l_1$, $l_2$, and $Q_0/M$ enter frequency expressions only in combined forms, giving rise to intrinsic parameter degeneracy. An effective-parameter set $\Theta =(M,X,C,\beta )$ is accordingly introduced to characterize these composite contributions. Bayesian MCMC parameter inference is carried out using HFQPO observational data from three black-hole X-ray binaries: GRO J1655--40, XTE J1550--564, and GRS 1915+105. The 68\% credible intervals of composite parameter $C$ all contain the Reissner--Nordström limit $C=1$, revealing no statistically significant net Lorentz-violating correction under our model assumptions. Distinct triples $(l_1,l_2,Q_0/M)$ yield identical QPO predictions, so HFQPO observations alone cannot disentangle Lorentz-violating and charge-related effects; precise constraints on these fundamental quantities require additional, more precise observational data.