通过光与轨道力学探测非线性电动力学源黑洞
Probing nonlinear electrodynamics-sourced black holes via light and orbital mechanics
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中文总结 AI 辅助
该研究通过光与轨道力学分析ModMax黑洞几何，发现夏皮罗时间延迟等对其双折射结构不敏感，萨格纳克效应可区分，还利用S2星进动约束了相关耦合，为探索NED场特征提供了方法。
中文摘要 AI 辅助
成熟的非线性电动力学（NED）模型通常具有一个额外参数，该参数与它们对线性电动力学的偏离程度相关。此外，从现象学角度来看，NED理论最引人入胜的结果之一是光子会根据有效几何遵循类光测地线。特别是对于双参数电磁拉格朗日密度，我们可能会观测到真空双折射现象，即光子可根据两种有效几何遵循类光测地线。在过去几十年里，人们已付出诸多努力以更好地理解有效光锥在NED理论中的作用，并约束该理论提供的额外自由参数。我们通过光与轨道力学研究ModMax黑洞（BH）几何，该黑洞是基于双参数拉格朗日密度的、具有充分动机的NED源黑洞，研究中考虑了夏皮罗时间、萨格纳克效应、引力与运动学红移以及轨道进动。我们发现非线性电磁场引入的修正可能十分显著。特别地，我们表明两种有效度规的夏皮罗时间延迟和引力红移完全相同，使得这些可观测量对ModMax电动力学的双折射结构不敏感。相比之下，萨格纳克效应和运动学红移仍能区分两种有效几何。此外，考虑S2恒星围绕人马座A$^{\boldsymbol{\u2605}}$的轨道近星点进动的轨道力学研究，为NED参数与ModMax黑洞荷质比之间的耦合提供了观测约束。总体而言，我们提供了逐步程序，用于从理论上探索NED场的特征并约束NED源黑洞模型的自由参数。
英文摘要
Well-founded models of nonlinear electrodynamics (NED) are typically characterized by an additional parameter associated with their deviation from linear electrodynamics. In addition to that, from a phenomenological point of view, one of the most intriguing results of NED theory is that photons follow null geodesics according to an effective geometry. In particular, for a two-parameter electromagnetic Lagrangian density, we might observe the vacuum birefringence phenomenon, i.e., photons can follow null geodesics according to two effective geometries. Over the past few decades, efforts have been made to better understand the role of effective light cones in NED theory, as well as to constrain the additional free parameters provided by the theory. We investigate the ModMax black hole (BH) geometry, which is a well-motivated NED-sourced BH based on a two-parameter Lagrangian density, via light and orbital mechanics, considering the Shapiro time, the Sagnac effect, the gravitational and kinematic shifts, and the orbital precession. We find that the corrections introduced by nonlinear electromagnetic fields can be significant. In particular, we show that the Shapiro time delay and the gravitational redshift are identical for both effective metrics, making these observables insensitive to the birefringent structure of ModMax electrodynamics. By contrast, the Sagnac effect and the kinematic shifts remain capable of distinguishing the two effective geometries. Moreover, the orbital mechanics investigation, considering the orbital periapsis precession of the S2 star around Sagittarius A$^{\star}$, provides an observational constraint on the coupling between the NED parameter and the charge-to-mass ratio of the ModMax BH. Generally speaking, we provide a step-by-step procedure for theoretically exploring signatures of NED fields and constraining the free parameters of NED-sourced BH models.
