pith. the verified trust layer for science. sign in

arxiv: 2511.21789 · v2 · submitted 2025-11-26 · 🌌 astro-ph.CO · hep-th

Cosmological Constraints on 4D Einstein-Gauss-Bonnet Gravity and Kaniadakis Holographic Dark Energy: Implications for Black Hole Shadows

Pith reviewed 2026-05-17 04:44 UTC · model grok-4.3

classification 🌌 astro-ph.CO hep-th
keywords Einstein-Gauss-Bonnet gravityKaniadakis holographic dark energyblack hole shadowscosmological constraintsdark energy modelsEvent Horizon Telescopephantom equation of state
0
0 comments X p. Extension

The pith

Black hole shadows retain a roughly 6 percent intrinsic deviation from LambdaCDM at redshift 2 in 4D Einstein-Gauss-Bonnet gravity with Kaniadakis holographic dark energy.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines the cosmological evolution of black hole shadows within 4D Einstein-Gauss-Bonnet gravity coupled to Kaniadakis holographic dark energy, taking the future event horizon as the infrared cutoff. Markov Chain Monte Carlo constraints from cosmic chronometers, Pantheon+ supernovae, and DESI baryon acoustic oscillations favor a phantom-like equation of state, with parameters consistent with general relativity and standard holographic dark energy at the one-sigma level. When the shadow radius is evolved including accretion and a dispersive plasma medium, environmental effects cause overall shrinkage at high redshift. A residual intrinsic deviation of about 6 percent nevertheless persists at redshift 2 relative to the LambdaCDM prediction under a conservative accretion setup. The results indicate that population analyses of black hole shadows may help isolate subtle dynamical dark energy effects from the standard cosmological model.

Core claim

In the 4D EGB gravity model coupled to KHDE, the best-fit parameters are c approximately 1.18, beta approximately 2.26, and alpha approximately -0.004. Standard holographic cases produce monotonic evolution of black hole mass and vacuum shadow radius, while phantom-divide crossing yields non-monotonic behavior. Inclusion of dispersive plasma leads to refraction-dominated shrinkage of the observable shadow, yet a residual intrinsic deviation of approximately 6 percent for the conservative accretion setup remains at redshift 2 relative to the LambdaCDM prediction.

What carries the argument

The observable black hole shadow radius evolved in a universe whose dark energy density is set by Kaniadakis entropy with the future event horizon as infrared cutoff.

If this is right

  • Phantom-like dark energy evolution produces non-monotonic changes in black hole mass and shadow radius over cosmic time.
  • The accretion history of black holes is sensitive to the thermodynamic sector of the dark energy model.
  • Plasma refraction dominates environmental effects on the shadow but leaves a detectable intrinsic difference at moderate redshifts.
  • Precision studies of black hole shadow populations can disentangle dynamical dark energy imprints from the standard cosmological paradigm.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Higher-resolution imaging of supermassive black holes at intermediate redshifts could directly test the predicted deviation.
  • The same shadow-evolution approach could be applied to other holographic dark energy models to search for distinctive signatures.
  • Confirmation of the deviation would supply an independent probe of dark energy dynamics that complements distance and expansion-rate measurements.

Load-bearing premise

The future event horizon serves as the infrared cutoff for the Kaniadakis holographic dark energy and the accretion history follows a fixed conservative setup whose details are not varied across scenarios.

What would settle it

A population measurement of black hole shadow radii at redshift 2 that agrees with the LambdaCDM prediction to better than 6 percent after subtraction of plasma and accretion effects would rule out the predicted residual intrinsic deviation.

Figures

Figures reproduced from arXiv: 2511.21789 by Hao-Peng Yan, Xiang-Qian Li, Xiao-Jun Yue.

Figure 1
Figure 1. Figure 1: Confidence contours (68% and 95%) and 1D posterior distributions for the model [PITH_FULL_IMAGE:figures/full_fig_p007_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: The Hubble parameter H(z) as a function of redshift. The blue solid line represents the best-fit KHDE model (H0 = 73.6, c = 0.70, α = 0.146), demonstrating strong agreement with the Cosmic Chronometers data (black dots). back to higher redshifts, the fluid transitions into the quintessence regime (w > −1). The EGB coupling α modulates this trajectory, with positive α suppressing the high-redshift value of … view at source ↗
Figure 3
Figure 3. Figure 3: Evolution of the dark energy equation of state [PITH_FULL_IMAGE:figures/full_fig_p010_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Evolution of the normalized black hole mass [PITH_FULL_IMAGE:figures/full_fig_p011_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Evolution of the black hole shadow radius in an optical vacuum ( [PITH_FULL_IMAGE:figures/full_fig_p012_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Impact of Plasma Environment. (a) Comparison of shadow evolution in optical vacuum (k0 = 0) versus dispersive plasma (k0 > 0) for fixed h = 1. (b) Sensitivity to the radial profile slope h for fixed density k0 = 0.2. The baseline model is Bekenstein-Hawking-GR. 2. Frequency Redshift (ω term): Due to the cosmic expansion, the photon frequency ω observed at a high redshift z relates to the observed frequency… view at source ↗
read the original abstract

The direct imaging of black holes by the Event Horizon Telescope (EHT) enables strong-field tests of gravity. We study the cosmological evolution and the black-hole shadow radius in 4D Einstein-Gauss-Bonnet (EGB) gravity coupled to Kaniadakis holographic dark energy (KHDE), adopting the future event horizon as the infrared cutoff. Using Cosmic Chronometers, Pantheon+ Type Ia supernovae, and DESI BAO data, we constrain the model with a Markov Chain Monte Carlo analysis. The best-fit values favor a phantom-like equation of state driven by Kaniadakis entropy ($c\simeq 1.18$, $\beta\simeq 2.26$), but $\beta$ remains weakly constrained ($\beta=2.26^{+0.11}_{-2.20}$), consistent with the standard holographic limit $\beta\to0$ at $1\sigma$. The EGB coupling is constrained to $\alpha\simeq -0.004$, also consistent with General Relativity ($\alpha=0$) at $1\sigma$. Guided by the posterior, we define five representative scenarios to probe the dynamical phase space. We find that the accretion history is highly sensitive to the thermodynamic sector: standard holographic cases yield monotonic evolution, whereas phantom-divide crossing leads to non-monotonic behavior in both the black hole mass and the vacuum shadow radius. Including a dispersive plasma medium, refraction dominates over intrinsic mass growth and induces an overall shrinkage of the observable shadow at high redshift; nevertheless, a residual intrinsic deviation of $\sim6\%$ (for our conservative accretion setup) persists at $z\simeq2$ relative to the $\Lambda$CDM prediction. These results indicate that, despite environmental dominance, precision population analyses of black hole shadows may help disentangle subtle dynamical dark-energy imprints from the standard cosmological paradigm.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The manuscript constrains 4D Einstein-Gauss-Bonnet gravity coupled to Kaniadakis holographic dark energy (with future event horizon as IR cutoff) using Cosmic Chronometers, Pantheon+ supernovae, and DESI BAO data via MCMC. Best-fit values favor phantom-like behavior (c≈1.18, β≈2.26, α≈−0.004), consistent with GR and standard holographic limits at 1σ. Five representative scenarios drawn from the posterior are used to evolve black-hole mass and shadow radius, incorporating accretion and a dispersive plasma medium. The analysis finds that refraction dominates and shrinks the observable shadow at high redshift, yet a residual ∼6% intrinsic deviation from ΛCDM persists at z≃2 for the adopted conservative accretion setup, suggesting that precision shadow population studies could isolate dynamical dark-energy effects.

Significance. If the central modeling assumptions prove robust, the work provides a concrete link between late-time cosmological constraints and strong-field observables, extending EHT shadow measurements to test modified gravity plus holographic dark energy. The MCMC analysis with three independent datasets, explicit consistency checks against GR and β→0 limits, and the identification of non-monotonic mass evolution in phantom-crossing cases constitute clear strengths that enhance reproducibility and falsifiability.

major comments (1)
  1. [Abstract and § on shadow evolution] Abstract and the section describing the five representative scenarios: the headline claim of a residual ∼6% intrinsic shadow deviation at z≃2 (and the consequent suggestion that precision population analyses can disentangle DE imprints) rests on a single fixed conservative accretion setup whose parameters are not varied across the scenarios. The text states that refraction dominates yet an offset remains “for our conservative accretion setup”; because the non-monotonic evolution is itself sensitive to the thermodynamic sector, the absence of any exploration of alternative Bondi rates, efficiencies, or plasma dispersion relations makes the persistence of the 6% offset load-bearing for the central assertion.
minor comments (2)
  1. [Model setup] The definition of the infrared cutoff and the precise form of the Kaniadakis entropy correction could be stated explicitly in the model section to aid reproducibility.
  2. [Figures] Figure captions for the shadow-radius evolution plots should indicate whether the curves include the plasma refraction term or show the vacuum case only.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the careful and constructive review of our manuscript. We address the major comment point by point below, indicating the revisions we intend to implement.

read point-by-point responses
  1. Referee: [Abstract and § on shadow evolution] Abstract and the section describing the five representative scenarios: the headline claim of a residual ∼6% intrinsic shadow deviation at z≃2 (and the consequent suggestion that precision population analyses can disentangle DE imprints) rests on a single fixed conservative accretion setup whose parameters are not varied across the scenarios. The text states that refraction dominates yet an offset remains “for our conservative accretion setup”; because the non-monotonic evolution is itself sensitive to the thermodynamic sector, the absence of any exploration of alternative Bondi rates, efficiencies, or plasma dispersion relations makes the persistence of the 6% offset load-bearing for the central assertion.

    Authors: We appreciate the referee highlighting this aspect of our analysis. The conservative accretion setup (including fixed Bondi rates, efficiencies, and plasma dispersion) was deliberately chosen as a representative baseline drawn from the literature to isolate the effects of the different dark-energy scenarios on black-hole mass and shadow evolution. This allows direct comparison of monotonic versus non-monotonic behaviors arising from the thermodynamic sector of the KHDE model. We agree that the precise numerical value of the residual offset could shift under alternative parameter choices and that a full sensitivity study would strengthen the claim. In the revised manuscript we will (i) qualify the abstract to state explicitly that the ∼6% figure applies to our conservative accretion setup and (ii) add a short paragraph in the shadow-evolution section discussing how variations in Bondi accretion parameters or plasma relations might modulate the offset while noting that refraction remains dominant. These changes will reduce the load-bearing character of the single-setup result without requiring an exhaustive new parameter scan, which lies beyond the present scope. revision: partial

Circularity Check

0 steps flagged

No significant circularity; derivation uses independent data constraints to explore separate observable implications

full rationale

The paper performs MCMC constraints on parameters (c, β, α) using external cosmological datasets (Cosmic Chronometers, Pantheon+, DESI BAO). Five representative scenarios are then selected from that posterior solely to illustrate dynamical behavior in the black-hole shadow calculation under a fixed accretion model. The reported ~6% residual deviation at z≃2 is a numerical outcome of integrating the constrained cosmology with the chosen accretion and plasma refraction prescriptions; it is not equivalent to any input datum or fit by construction. No self-definitional equations, fitted quantities renamed as predictions, or load-bearing self-citations appear in the derivation chain. The conservative accretion setup is an explicit modeling choice whose sensitivity is acknowledged but does not create a circular reduction.

Axiom & Free-Parameter Ledger

3 free parameters · 2 axioms · 0 invented entities

The model rests on the standard FLRW metric, the future event horizon as IR cutoff, and the specific form of Kaniadakis entropy; the accretion history and plasma dispersion are additional modeling choices not derived from first principles.

free parameters (3)
  • alpha (EGB coupling)
    Fitted to cosmological data; best-fit ~ -0.004
  • c (holographic parameter)
    Fitted; best-fit ~1.18
  • beta (Kaniadakis parameter)
    Fitted; best-fit ~2.26 with large uncertainty
axioms (2)
  • domain assumption Future event horizon as infrared cutoff for holographic dark energy
    Stated in abstract as the adopted cutoff
  • standard math FLRW background with standard matter and radiation components
    Implicit in cosmological evolution equations

pith-pipeline@v0.9.0 · 5660 in / 1655 out tokens · 29896 ms · 2026-05-17T04:44:12.136877+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

36 extracted references · 36 canonical work pages

  1. [1]

    First m87 event horizon telescope results

    Event Horizon Telescope Collaboration. First m87 event horizon telescope results. i. the shadow of the supermassive black hole.Astrophys. J. Lett., 875:L1, 2019

  2. [2]

    First sagittarius a* event horizon telescope results

    Event Horizon Telescope Collaboration. First sagittarius a* event horizon telescope results. i. the shadow of the supermassive black hole in the center of the milky way.Astrophys. J. Lett., 930:L12, 2022

  3. [3]

    Glavan and C

    D. Glavan and C. Lin. Einstein-gauss-bonnet gravity in four-dimensional spacetime.Phys. Rev. Lett., 124:081301, 2020

  4. [4]

    Lu and Yi Pang

    H. Lu and Yi Pang. Horndeski gravity asD→4 limit of Gauss-Bonnet.Phys. Lett. B, 809:135717, 2020

  5. [5]

    A note on the novel 4D Einstein–Gauss–Bonnet gravity.Commun

    Wen-Yuan Ai. A note on the novel 4D Einstein–Gauss–Bonnet gravity.Commun. Theor. Phys., 72(9):095402, 2020

  6. [6]

    Hennigar, David Kubizˇ n´ ak, Robert B

    Robie A. Hennigar, David Kubizˇ n´ ak, Robert B. Mann, and Christopher Pollack. On taking the D→4 limit of Gauss-Bonnet gravity: theory and solutions.JHEP, 07:027, 2020

  7. [7]

    Pedro G. S. Fernandes. Charged black holes in AdS spaces in 4D Einstein Gauss-Bonnet gravity.Phys. Lett. B, 805:135468, 2020

  8. [8]

    Extended thermodynamics and microstructures of four- dimensional charged Gauss-Bonnet black hole in AdS space.Phys

    Shao-Wen Wei and Yu-Xiao Liu. Extended thermodynamics and microstructures of four- dimensional charged Gauss-Bonnet black hole in AdS space.Phys. Rev. D, 101(10):104018, 2020

  9. [9]

    Naveena Kumara, C

    Kartheek Hegde, A. Naveena Kumara, C. L. Ahmed Rizwan, Md Sabir Ali, and K. M. Ajith. Null geodesics and thermodynamic phase transition of four-dimensional Gauss–Bonnet AdS black hole.Annals Phys., 429:168461, 2021

  10. [10]

    Thermodynamics and circular motion in a 4D Einstein–Gauss–Bonnet black hole embedded in quintessence.Can

    Indrajit Halder. Thermodynamics and circular motion in a 4D Einstein–Gauss–Bonnet black hole embedded in quintessence.Can. J. Phys., 103(10):978–992, 2025. 15

  11. [11]

    Hawking-Page transition in 4D Einstein-Gauss- Bonnet gravity.Nucl

    Xiao-yan Hu, Yuan-zhang Cui, and Wei Xu. Hawking-Page transition in 4D Einstein-Gauss- Bonnet gravity.Nucl. Phys. B, 1012:116821, 2025

  12. [12]

    M. S. Churilova. Quasinormal modes of the test fields in the consistent 4D Einstein–Gauss- Bonnet–(anti)de Sitter gravity.Annals Phys., 427:168425, 2021

  13. [13]

    R. A. Konoplya and A. F. Zinhailo. Quasinormal modes, stability and shadows of a black hole in the 4D Einstein–Gauss–Bonnet gravity.Eur. Phys. J. C, 80(11):1049, 2020

  14. [14]

    Ram´ on B´ ecar, P. A. Gonz´ alez, Eleftherios Papantonopoulos, and Yerko V´ asquez. Massive scalar field perturbations of 4D de Sitter–Einstein-Gauss-Bonnet black holes.Phys. Rev. D, 111(12):124013, 2025

  15. [15]

    Zubair, Muhammad Ali Raza, Furkat Sarikulov, and Javlon Rayimbaev

    M. Zubair, Muhammad Ali Raza, Furkat Sarikulov, and Javlon Rayimbaev. 4D Einstein- Gauss-Bonnet black hole in Power-Yang-Mills field: a shadow study.JCAP, 10:058, 2023

  16. [16]

    Javier Bad´ ıa and Ernesto F. Eiroa. Shadow of black holes with a plasma environment in 4D Einstein-Gauss-Bonnet gravity. In16th Marcel Grossmann Meeting on Recent Devel- opments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories, 11 2021

  17. [17]

    Kumar and S

    R. Kumar and S. G. Ghosh. Rotating black holes in 4d einstein-gauss-bonnet gravity and its shadow.JCAP, 07:053, 2020

  18. [18]

    Double shadow of a 4D Einstein–Gauss–Bonnet black hole and the connection between them with quasinormal modes.Mod

    Tian-Tian Liu, He-Xu Zhang, Yu-Hang Feng, Jian-Bo Deng, and Xian-Ru Hu. Double shadow of a 4D Einstein–Gauss–Bonnet black hole and the connection between them with quasinormal modes.Mod. Phys. Lett. A, 37(24):2250154, 2022

  19. [19]

    Khodabakhshi, M

    H. Khodabakhshi, M. Farhang, and H. L¨ u. Observational feasibility of 4D Einstein-Gauss- Bonnet cosmology: bouncing and non-bouncing universes.JCAP, 05:024, 2024

  20. [20]

    Carola M. A. Zanoletti, Brayden R. Hull, C. Danielle Leonard, and Robert B. Mann. Cosmological constraints on 4-dimensional Einstein-Gauss-Bonnet gravity.JCAP, 01:043, 2024

  21. [21]

    Observational constraints on the regularized 4d einstein-gauss-bonnet theory of gravity.Phys

    Timothy Clifton, Pedro Carrilho, Pedro GS Fernandes, and David J Mulryne. Observational constraints on the regularized 4d einstein-gauss-bonnet theory of gravity.Phys. Rev. D, 102(8):084058, 2020

  22. [22]

    Kaniadakis

    G. Kaniadakis. Statistical mechanics in the context of special relativity.Phys. Rev. E, 66:056125, 2002

  23. [23]

    Statistical mechanics in the context of special relativity

    Giorgio Kaniadakis. Statistical mechanics in the context of special relativity. ii.Phys. Rev. E, 72(3):036108, 2005

  24. [24]

    Saridakis, and Kuralay Yesmakhanova

    Niki Drepanou, Andreas Lymperis, Emmanuel N. Saridakis, and Kuralay Yesmakhanova. Kaniadakis holographic dark energy and cosmology.Eur. Phys. J. C, 82(5):449, 2022

  25. [25]

    Hern´ andez-Almada, Genly Leon, Juan Maga˜ na, Miguel A

    A. Hern´ andez-Almada, Genly Leon, Juan Maga˜ na, Miguel A. Garc´ ıa-Aspeitia, V. Motta, Emmanuel N. Saridakis, and Kuralay Yesmakhanova. Kaniadakis-holographic dark energy: observational constraints and global dynamics.Mon. Not. Roy. Astron. Soc., 511(3):4147– 4158, 2022

  26. [26]

    Revisiting the constraints on interacting holographic dark energy models with current ob- servational data.Eur

    Xiaofang Shen, Bing Xu, Kaituo Zhang, Xiangyun Fu, Liangliang Ren, and Zelin Zhang. Revisiting the constraints on interacting holographic dark energy models with current ob- servational data.Eur. Phys. J. C, 85(9):992, 2025. 16

  27. [27]

    Saridakis

    Andreas Lymperis, Spyros Basilakos, and Emmanuel N. Saridakis. Modified cosmology through Kaniadakis horizon entropy.Eur. Phys. J. C, 81(11):1037, 2021

  28. [28]

    Babichev, V

    E. Babichev, V. Dokuchaev, and Y. Eroshenko. Black hole mass decreasing due to phantom energy accretion.Phys. Rev. Lett., 93:021102, 2004

  29. [29]

    Perlick, O

    V. Perlick, O. Y. Tsupko, and G. S. Bisnovatyi-Kogan. Influence of a plasma on the shadow of a spherically symmetric black hole.Phys. Rev. D, 92:104031, 2015

  30. [30]

    Optical appearance and shadow of Kalb–Ramond black hole: effects of plasma and accretion models.Eur

    Mou Xu, Ruonan Li, Jianbo Lu, Shining Yang, and Shu-Min Wu. Optical appearance and shadow of Kalb–Ramond black hole: effects of plasma and accretion models.Eur. Phys. J. C, 85(6):676, 2025

  31. [31]

    P. G. S. Fernandes, P. Carrilho, T. Clifton, and D. J. Mulryne. The 4d einstein-gauss-bonnet theory of gravity: a review.Class. Quant. Grav., 39:063001, 2022

  32. [32]

    Mukherjee, U

    P. Mukherjee, U. Debnath, H. Chaudhary, and G. Mustafa. Constraining the parameters of generalized and viscous modified chaplygin gas and black hole accretion in einstein-aether gravity.Eur. Phys. J. C, 84:930, 2024

  33. [33]

    Accretion of Holo- graphic Dark Energy : Dependency only upon Horizon Radius of Expanding Universe

    Ritabrata Biswas, Nairwita Mazumder, and Subenoy Chakraborty. Accretion of Holo- graphic Dark Energy : Dependency only upon Horizon Radius of Expanding Universe. Astrophys. Space Sci., 335:603–609, 2011

  34. [34]

    Torrado and A

    J. Torrado and A. Lewis. Cobaya: Code for bayesian analysis of hierarchical physical models.J. Cosmol. Astropart. Phys., 2021(05):057, 2021

  35. [35]

    Moresco and et al

    M. Moresco and et al. A 6% measurement of the hubble parameter at z∼0.45: direct evidence of the epoch of cosmic re-acceleration.J. Cosmol. Astropart. Phys., 2016(05):014, 2016

  36. [36]

    Brout et al

    D. Brout et al. The pantheon+ analysis: Cosmological constraints.Astrophys. J., 938:110, 2022. 17