Search for a Variation of the Fine Structure Constant around the Supermassive Black Hole in Our Galactic Center

Hees, A.; Do, Tuan; Roberts, B. M.; Ghez, A. M.; Nishiyama, Shogo; Bentley, Rory O.; Gautam, Abhimat K.; Jia, Siyao; Kara, T.; Lu, Jessica R.; Saida, Hiromi; Sakai, Shoko; Takahashi, Mizuki; Takamori, Yohsuke

doi:10.1103/physrevlett.124.081101

“…As in the case of the precession of Mercury in the Solar System, the constraints from the latter test are expressed in terms of the usual coefficients of the parametric post-Newtonian (PPN) framework [2]. Additional constraints can be imposed on equivalence principle violations via potential changes in the fine-structure constant [16], or on the Yuwaka strength and scale of a putative fifth force [17].…”

Section: Introductionmentioning

confidence: 99%

Probing the black hole metric: Black hole shadows and binary black-hole inspirals

Psaltis

¹

,

Talbot

²

,

Payne

³

et al. 2021

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In general relativity, the spacetimes of black holes have three fundamental properties: (i) they are the same, to the lowest order in spin, as the metrics of stellar objects; (ii) they are independent of mass when expressed in geometric units; and (iii) they are described by the Kerr metric. In this paper, we quantify the upper bounds on potential black-hole metric deviations imposed by observations of black-hole shadows and of binary black-hole inspirals in order to explore the current experimental limits on possible violations of the last two predictions. We find that both types of experiments provide correlated constraints on deviation parameters that are primarily in the tt components of the spacetimes when expressed in areal coordinates. We conclude that, currently, there is no evidence for deviations from the Kerr metric across the 8 orders of magnitude in mass and 16 orders in curvature spanned by the two types of black holes. Moreover, because of the particular masses of black holes in the current sample of gravitational-wave sources, the correlations imposed by the two experiments are aligned and of similar magnitudes when expressed in terms of the far-field, post-Newtonian predictions of the metrics. If a future coalescing blackhole binary with two low-mass (e.g., ∼3 M ⊙ ) components is discovered, the degeneracy between the deviation parameters can be broken by combining the inspiral constraints with those from the black-hole shadow measurements.

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“…Then for the experimental test of this new coupling, one could detect whether atomic spectra at different locations represent the same fine structure constant such as a given kind of atom on Earth and the same kind of atom on stars in orbits of supermassive black holes. We refer readers to [52][53][54] for more details.…”

Section: The Model Of Eep Violationmentioning

confidence: 99%

“…One of the main challenges of modern physics is the confirmation of the EEP at different scales and different contexts both from the theoretical and the experimental points of view [42][43][44][45][46][47][48][49][50][51]. However, the current experiments on testing EEP are mainly conducted on the scale of Newtonian or post-Newtonian gravity [52][53][54][55][56][57][58][59][60][61]. As for more extreme gravitational field such as that around the horizon of black holes, whether EEP holds or not is still unknown.…”

Section: Introductionmentioning

confidence: 99%

New test on the Einstein equivalence principle through the photon ring of black holes

Li

¹

,

Zhao

²

,

Cai

³

2021

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Einstein equivalence principle (EEP), as one of the foundations of general relativity, is a fundamental test of gravity theories. In this paper, we propose a new method to test the EEP of electromagnetic interactions through observations of black hole photon rings, which naturally extends the scale of Newtonian and post-Newtonian gravity where the EEP violation through a variable fine structure constant has been well constrained to that of stronger gravity. We start from a general form of Lagrangian that violates EEP, where a specific EEP violation model could be regarded as one of the cases of this Lagrangian. Within the geometrical optical approximation, we find that the dispersion relation of photons is modified: for photons moving in circular orbit, the dispersion relation simplifies, and behaves such that photons with different linear polarizations perceive different gravitational potentials. This makes the size of black hole photon ring depend on polarization. Further assuming that the EEP violation is small, we derive an approximate analytic expression for spherical black holes showing that the change in size of the photon ring is proportional to the violation parameters. We also discuss several cases of this analytic expression for specific models. Finally, we explore the effects of black hole rotation and derive a modified proportionality relation between the change in size of photon ring and the violation parameters. The numerical and analytic results show that the influence of black hole rotation on the constraints of EEP violation is relatively weak for small magnitude of EEP violation and small rotation speed of black holes.

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“…A possible time variation of the fine structure constant during the Big Bang nucleosynthesis (BBN) [36] is also explored. Moreover, in the context of a supermassive black hole in the Galactic Center with a high gravitational poten-tial, it is used late-type evolved giant stars data from the S-star [37]. Recently, the Ref.…”

Section: Introductionmentioning

confidence: 99%

Probing variation of the fine-structure constant in runaway dilaton models using Strong Gravitational Lensing and Type Ia Supernovae

Colaço

¹

,

Holanda

²

,

Silva

³

2021

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In order to probe a possible time variation of the fine-structure constant ($$\alpha $$ α ), we propose a new method based on Strong Gravitational Lensing and Type Ia Supernovae observations. By considering a class of runaway dilaton models, where $$\frac{\Delta \alpha }{\alpha }= - \gamma \ln {(1+z)}$$ Δ α α = - γ ln ( 1 + z ) , we obtain constraints on $$\frac{\Delta \alpha }{\alpha }$$ Δ α α at the level $$\gamma \sim 10^{-2}$$ γ ∼ 10 - 2 ($$\gamma $$ γ captures the physical properties of the model). Since the data set covers the redshift range $$0.075 \le z \le 2.2649$$ 0.075 ≤ z ≤ 2.2649 , the constraints derived here provide independent bounds on a possible time variation of $$\alpha $$ α at low, intermediate and high redshifts.

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Search for a Variation of the Fine Structure Constant around the Supermassive Black Hole in Our Galactic Center

Cited by 48 publications

References 121 publications

Probing the black hole metric: Black hole shadows and binary black-hole inspirals

Probing the black hole metric: Black hole shadows and binary black-hole inspirals

New test on the Einstein equivalence principle through the photon ring of black holes

Probing variation of the fine-structure constant in runaway dilaton models using Strong Gravitational Lensing and Type Ia Supernovae

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