Constraint on magnetized black bounce spacetime from HFQPOs data and the selection of resonance models via information criterion

TL;DR

The paper tackles HFQPOs in microquasars by modeling charged-particle dynamics in a magnetized Simpson–Visser spacetime, linking ISCO shifts and epicyclic frequencies to resonance models that explain the observed 3:2 HFQPO ratios. It combines chi-squared data fitting with AIC model selection to constrain the SV regularization parameter $a$ and the external magnetic parameter $\mathcal{B}$, finding that a magnetized SV spacetime provides a better fit than the no-field case. The strongest evidence corresponds to the ER8 resonance variant, with moderate support for ER3 and weak support for ER6/ER7, while other variants are disfavored; this yields 68% CL bounds such as $0\le a<0.736$ and magnetic field strengths of order $B\sim10^{-5}$–$10^{-4}$ G for electrons or $B\sim10^{-2}$–$10^{-1}$ G for protons, depending on the particle. The results imply that HFQPO observations favor a magnetized regular black hole interpretation and demonstrate the utility of combining dynamical modelling with information-theoretic model selection to discriminate resonance mechanisms.

Abstract

This paper primarily explores the dynamics of charged particle in the magnetized SV spacetime, and constrains the parameters of the SV spacetime along with its surrounding magnetic fields. The constraints are given by using $χ^2$ analysis combined with high-frequency quasi-periodic oscillation (HFQPO) data observed from three microquasars: GRS 1915+105, XTE 1550-564, and GRO J1655-40. The results indicate that the magnetic field significantly influences the position of the innermost stable circular orbit of charged particle and frequency distribution of epicyclic motion, which excites more resonance model variants, enhancing observational effects. Additionally, we employ the Akaike Information Criterion (AIC) to evaluate resonance model and its various variants. The support for different models from observational data shows significant variation: $E R_8$ as the best model is supported strongly, $ER_3$ model has moderate evidence of support, $ER_6$ and $ER_7$ models are considerably less support, while other resonance models have essentially no support. For models more supported by the observational data, the allowed ranges of the regularization parameter: $0\leq a<0.736$ ($68\%$ confidence level) suggests that HFQPOs data support the magnetized black bounce spacetime as a regular black hole, and the smaller value of the regularization parameter indicates a possibility of the presence of quantum effects. According to the constraint results, we get the best-fit values of magnetic field strength around $10^{-5}\sim 10^{-4}$ GS for electrons and around $10^{-2}\sim 10^{-1}$ GS for protons. Finally, as a comparison, we test the SV spacetime without a magnetic field using microquasar observational data, and the calculated results of AIC show that this case is incompatible with the HFQPOs data, further supporting the existence of a magnetic field in SV spacetime.

Figures (6)

• Figure 1: The variation of the ISCO position of a charged particle with the magnetic field, where the particle is considered as moving in SV spacetime around different types of celestial bodies.
• Figure 2: The variation curves of the angular frequency $\omega_r$ (solid line), $\omega_\theta$ (dashed line), $\omega_\phi$ (dotted line) of a test particle with respect to the radial coordinate $r$ in magnetized SV spacetime, under the influence of the regularization parameter $a$ and the magnetic parameter $\mathcal{B}$, along with the image of $\omega_L$ (dot-dash line).
• Figure 3: The variation of the $3: 2$ resonance position with the magnetic field parameter in four types of magnetized SV spacetimes under the resonance models $E R_0-E R_9$.
• Figure 4: The $68 \%$ and $95 \%$ confidence regions of the magnetic parameter $\mathcal{B}$ and the regularization parameter $a$ under $E R_0-E R_5$ resonance models.
• Figure 5: The $68 \%$ and $95 \%$ confidence regions of the magnetic parameter $\mathcal{B}$ and the regularization parameter $a$ under $E R_6-E R_9$ resonance models.