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arxiv: 2605.04631 · v1 · submitted 2026-05-06 · 🌌 astro-ph.HE · gr-qc· hep-th

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Dynamics and Radiative Signatures of Accretion Flows onto a Kerr-like Wormhole

Jing-ze Xia , Hong-Xuan Jiang , Cheng Liu , Yosuke Mizuno
Authors on Pith no claims yet

Pith reviewed 2026-05-08 17:00 UTC · model grok-4.3

classification 🌌 astro-ph.HE gr-qchep-th
keywords wormholeaccretion flowKerr black-bounce metricGRMHD simulationradiative transferthroat emissionquasi-periodic modulationhorizon-scale imaging
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The pith

Accretion onto a Kerr-like wormhole produces dominant throat emissions that create quasi-periodic modulations in light curves.

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

The paper runs general relativistic magnetohydrodynamic simulations of a magnetized torus accreting onto one mouth of a wormhole described by a Kerr black-bounce metric with fixed throat size. It then computes the emitted radiation and finds that light produced right at the throat can overpower contributions from other regions. This throat light supplies most of the time-varying part of the signal and imprints repeating brightness cycles. A reader cares because these cycles differ from anything expected around a black hole and could be checked against telescope data on compact objects. The work also shows how the object's spin couples the flows on both sides of the wormhole through frame-dragging.

Core claim

In simulations initialized with a magnetized geometrically thick torus near one mouth of the wormhole while the opposite mouth starts empty, the spin parameter alters dynamical properties on both sides through frame-dragging. The subsequent radiative transfer calculations at 230 GHz show that emissions from the immediate vicinity of the throat dominate the images and light curves, supplying the variable component and producing clear quasi-periodic modulation, in contrast to the behavior around a Kerr black hole.

What carries the argument

The throat in the Kerr black-bounce metric with fixed parameter ℓ = 2.5 M, which permits material and photon trajectories to connect two asymptotic regions and allows throat-proximal emission to dominate the observed signal.

If this is right

  • Spin couples the accretion dynamics on both sides of the wormhole.
  • Throat emissions supply the main variable component of the radiative signal.
  • Clear quasi-periodic modulation appears in the computed light curves.
  • These signatures differ from those of a Kerr black hole and could be searched for in horizon-scale data.

Where Pith is reading between the lines

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

  • Varying the throat size parameter would test how strongly emission dominance depends on that choice.
  • Adding gas flow from the second mouth could reduce or eliminate the predicted modulation.
  • The same simulation pipeline could be applied to other horizonless compact objects to compare their light-curve variability.

Load-bearing premise

The opposite mouth of the wormhole remains free of gas and standard magnetohydrodynamics applies without additional effects at the throat.

What would settle it

Horizon-scale light curves at 230 GHz that lack any quasi-periodic modulation would show that throat emissions do not dominate under the modeled conditions.

Figures

Figures reproduced from arXiv: 2605.04631 by Cheng Liu, Hong-Xuan Jiang, Jing-ze Xia, Yosuke Mizuno.

Figure 1
Figure 1. Figure 1: The mass flux rate at different mouth (top: r = 2 M and middle: r = −2 M) from 2D GRMHD simulations, M2Da03 and M2Da09 (left), and 3D cases M3Da00, M3Da03, and M3Da09 (right), respectively. We note that mass flux is inflow at r = 2 M (mouth A side) while the mass flux becomes outflow at r = −2 M (mouth B side). The lower panels show the magnetic flux for each model, evaluated at mouth A (r = 2 M). ⟨M˙ ⟩ = … view at source ↗
Figure 2
Figure 2. Figure 2: Azimuthally and time-averaged (t = 15,000–17,000 M) logarithmic density (left), toroidal component of magnetic field, bϕ (middle), and Lorentz factor (right) for the 3D cases M3Da03 (top) and M3Da09 (bottom). The black contour and dashed line in the density panels correspond to σ = 1 and 10, respectively. The white contour in the Lorentz-factor panels denotes −hut = 1. For each sub-figure, the right panel … view at source ↗
Figure 4
Figure 4. Figure 4: Time-averaged radial profiles of the density and mass flux rate M˙ for the models M3Da00, M3Da03 and M3Da09. Averaged time range is from t = 15, 000 M to 17, 000 M. at r = 0 M (see Appendix B for a detailed discussion). This behavior is consistent with the centrally enhanced density discussed above, which manifests itself as the bright center band of the density diagram (lower panel) in view at source ↗
Figure 5
Figure 5. Figure 5: shows the analytically calculated critical curves for different values of the spin parameter, using the same throat parameter ℓ = 2.5 M with an inclination angle of i = 90◦ . As the spin increases, the shape of the Kerr branch is progressively modified, becoming more “D-shaped” asymmetry (H.-M. Wang et al. 2019; J. M. Bardeen 1973). The throat branch for a fixed value of ℓ is also influenced by the spin, w… view at source ↗
Figure 6
Figure 6. Figure 6: The time and azimuthal averaged emissivity proxy j for the models M3Da03 and M3Da09. Averaged time range is from 15, 000 M to 17, 000 M. a far distance in the position of positive radius. As shown in view at source ↗
Figure 7
Figure 7. Figure 7 view at source ↗
Figure 8
Figure 8. Figure 8: Same as view at source ↗
Figure 9
Figure 9. Figure 9: The light curve for M3Da03 and M3Da09. The lower panels show the wavelet power spectrum over the same time interval as in the upper panel, together with the analytical period–radius relation (Pr(r) and Pθ(r)) from E. Deligianni et al. (2021). We find that the dominant oscillation period is associated with the inner region of the flow, i.e., the vicinity of the throat, with the theoretical curve (Pθ(r)) ove… view at source ↗
read the original abstract

Wormholes are a hypothetical object that connects disparate points in spacetime. It is a theoretically well-motivated black hole alternative and offers a potential observationally testable arena for probing strong-field gravity with horizon-scale images. We perform general relativistic magnetohydrodynamic (GRMHD) simulations and general relativistic radiative transfer (GRRT) calculations of accretion flows onto a Kerr-like wormhole. Adopting a Kerr black-bounce metric with a fixed throat parameter $\ell = 2.5\,\rm M$, we explore the effects of spin using both two- and three-dimensional simulations. The accretion flow is initialized as a magnetized geometrically thick torus near one mouth of the wormhole, while the opposite mouth is initially gas-free. We find that the spin parameter influences the dynamical properties on both sides of the wormhole through the frame-dragging effects. Based on the GRMHD results, we compute ray-traced images at $230\,\mathrm{GHz}$ using \texttt{RAPTOR}, and analyze the horizon-scale image structure through higher-order photon trajectories. Our GRRT calculations show that emissions originating from the immediate vicinity of the throat can dominate, in contrast to the case of a Kerr black hole. It provides the variable component of the signal and imprints a clear quasi-periodic modulation in the light curves. These properties would be useful to either confirm or rule out such exotic compact objects through horizon-scale observations.

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

2 major / 2 minor

Summary. The manuscript performs 2D and 3D GRMHD simulations of a magnetized torus accreting onto one mouth of a Kerr-like wormhole (black-bounce metric with fixed throat parameter ℓ = 2.5 M) while the opposite mouth starts gas-free. Varying spin, it evolves the system under standard GRMHD and then computes 230 GHz images and light curves via GRRT, claiming that throat-vicinity emission dominates the signal (unlike Kerr BHs), supplies the variable component, and imprints clear quasi-periodic modulation useful for observational tests.

Significance. If the no-crossing assumption and numerical robustness hold, the work supplies a concrete, falsifiable variability signature that could distinguish wormhole candidates from black holes at horizon scales, extending standard GRMHD/GRRT techniques to an exotic metric.

major comments (2)
  1. [Simulation initialization and evolution] The headline result (throat emission dominating the 230 GHz signal and producing distinct QPO modulation) is load-bearing on the opposite mouth remaining gas-free throughout the evolution. The abstract states the opposite mouth is 'initially gas-free' and the metric is traversable with frame-dragging evolved on both sides, yet no explicit check for net mass flux, density buildup, or coordinate-crossing is reported; modest crossing would populate the second mouth and weaken the claimed single-sided discriminant.
  2. [Numerical methods and results] No grid resolution, convergence tests, or quantitative error analysis (e.g., mass conservation across the throat or image variability convergence) are described, undermining verification of the dynamical properties and the GRRT claim that throat emission dominates.
minor comments (2)
  1. The abstract mentions analysis of 'higher-order photon trajectories' in the images; the manuscript should specify how these are isolated and weighted in the RAPTOR ray-tracing.
  2. The fixed choice ℓ = 2.5 M is stated without a sensitivity study; a brief exploration of nearby values would strengthen the robustness claim.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive and detailed comments on our manuscript. We address each major point below and will incorporate revisions to strengthen the presentation of our results.

read point-by-point responses

  1. Referee: The headline result (throat emission dominating the 230 GHz signal and producing distinct QPO modulation) is load-bearing on the opposite mouth remaining gas-free throughout the evolution. The abstract states the opposite mouth is 'initially gas-free' and the metric is traversable with frame-dragging evolved on both sides, yet no explicit check for net mass flux, density buildup, or coordinate-crossing is reported; modest crossing would populate the second mouth and weaken the claimed single-sided discriminant.

    Authors: We agree that explicit verification of the gas-free condition on the opposite mouth is necessary to support the single-sided accretion interpretation. Our simulations were initialized with zero density on the far side and evolved under the traversable metric, with no visible mass transfer observed in the data. However, quantitative checks were not reported. In the revised manuscript we will add time series of the integrated density and net mass flux through the throat, confirming that crossing remains negligible over the simulated duration. This will directly address the concern and reinforce the robustness of the throat-dominated emission claim. revision: yes

  2. Referee: No grid resolution, convergence tests, or quantitative error analysis (e.g., mass conservation across the throat or image variability convergence) are described, undermining verification of the dynamical properties and the GRRT claim that throat emission dominates.

    Authors: We acknowledge that the absence of resolution details and convergence tests limits the ability of readers to assess numerical reliability. The original manuscript omitted these elements. In the revision we will specify the grid resolutions employed for both the 2D and 3D GRMHD runs, include convergence tests for global quantities such as mass accretion rate and total energy, and demonstrate that the 230 GHz light-curve variability and image morphology converge with increasing resolution. For the GRRT post-processing we will report the ray-tracing parameters and show that the throat-emission dominance is insensitive to modest changes in resolution. revision: yes

Circularity Check

0 steps flagged

No circularity: forward GRMHD/GRRT simulations on fixed metric

full rationale

The paper initializes standard GRMHD equations on the Kerr black-bounce metric (ℓ fixed at 2.5M) with a magnetized torus on one side and explicit gas-free condition on the other, evolves the flow, then applies GRRT to compute 230 GHz images and light curves. The claimed throat-vicinity dominance and QPO modulation are direct numerical outputs under these inputs, not re-derived by fitting, self-definition, or load-bearing self-citation. No parameters are tuned to target observables; the opposite-mouth assumption is an explicit initial condition rather than a derived result. The chain is self-contained forward modeling.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 1 invented entities

The central claim rests on standard GRMHD and radiative transfer applied to a specific wormhole metric; the main added elements are the numerical setup and the resulting light-curve signature.

free parameters (2)
  • throat parameter ℓ = 2.5 M
    Fixed at 2.5 M for the Kerr black-bounce metric used throughout the simulations.
  • spin parameter a = varied
    Varied across simulations to explore frame-dragging effects.
axioms (2)
  • domain assumption General relativistic magnetohydrodynamics equations govern the accretion flow
    Invoked for all 2D and 3D simulations of the magnetized torus.
  • domain assumption The Kerr black-bounce metric with fixed ℓ describes a traversable wormhole spacetime
    Adopted as the background geometry for both sides of the wormhole.
invented entities (1)
  • Kerr-like wormhole with throat parameter ℓ no independent evidence
    purpose: Spacetime geometry connecting two asymptotic regions without an event horizon
    Postulated as the central object; no independent observational evidence is supplied beyond the metric choice.

pith-pipeline@v0.9.0 · 5568 in / 1639 out tokens · 78938 ms · 2026-05-08T17:00:44.248832+00:00 · methodology

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Reference graph

Works this paper leans on

34 extracted references · 33 canonical work pages · 1 internal anchor

  1. [1]

    Bardeen, J. M. 1973, in Black Holes (Les Astres Occlus), ed. C. Dewitt & B. S. Dewitt, 215–239

    1973

  2. [2]

    2018, A&A, 613, A2, doi: 10.1051/0004-6361/201732149

    Bronzwaer, T., Davelaar, J., Younsi, Z., et al. 2018, A&A, 613, A2, doi: 10.1051/0004-6361/201732149 14 Figure B1.The effective potential for models with different spin parameters at fixedℓ= 2.5. Figure C1.The time-averaged GRRT images observed from the mouth B side are shown together with the overlaid critical curve forM3Da09. We note that the different ...

    work page doi:10.1051/0004-6361/201732149 2018

  3. [3]

    Carter, Global structure of the Kerr family of gravitational fields, Phys

    Carter, B. 1968, Physical Review, 174, 1559, doi: 10.1103/PhysRev.174.1559

    work page doi:10.1103/physrev.174.1559 1968

  4. [4]

    On the Cuspy Structure of Rotating Wormhole Shadows

    Cheng, P., Xu, R.-F., & Zhao, P. 2026, https://arxiv.org/abs/2602.14182

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  5. [5]

    2024, PhRvD, 109, 103034, doi: 10.1103/PhysRevD.109.103034

    Combi, L., Yang, H., Gutierrez, E., et al. 2024, Phys. Rev. D, 109, 103034, doi: 10.1103/PhysRevD.109.103034 de Kleuver, J., Bronzwaer, T., Falcke, H., et al. 2024, A&A, 689, A197, doi: 10.1051/0004-6361/202348489

    work page doi:10.1103/physrevd.109.103034 2024

  6. [6]

    2021, PhRvD, 104, 024048, doi: 10.1103/PhysRevD.104.024048

    Zheleva, R. 2021, PhRvD, 104, 024048, doi: 10.1103/PhysRevD.104.024048

    work page doi:10.1103/physrevd.104.024048 2021

  7. [7]

    K., Uniyal, A., & Mizuno, Y

    Dihingia, I. K., Uniyal, A., & Mizuno, Y. 2025, ApJ, 978, 44, doi: 10.3847/1538-4357/ad9600 Ertola Urtubey, M., & P´ erez, D. 2025, European Physical Journal C, 85, 1178, doi: 10.1140/epjc/s10052-025-14919-y Event Horizon Telescope Collaboration, Akiyama, K.,

    work page doi:10.3847/1538-4357/ad9600 2025

  8. [8]

    2019a, 875, L5, doi: 10.3847/2041-8213/ab0f43 Event Horizon Telescope Collaboration, Akiyama, K.,

    Alberdi, A., et al. 2019a, ApJL, 875, L5, doi: 10.3847/2041-8213/ab0f43 Event Horizon Telescope Collaboration, Akiyama, K.,

    work page doi:10.3847/2041-8213/ab0f43 2041

  9. [9]

    2019b, ApJL, 875, L6, doi: 10.3847/2041-8213/ab1141 Event Horizon Telescope Collaboration, et al

    Alberdi, A., et al. 2019b, ApJL, 875, L6, doi: 10.3847/2041-8213/ab1141 15 Figure D1.MRI quality factor for modelM3Da09att= 17,000 M. Event Horizon Telescope Collaboration, Akiyama, K.,

    work page doi:10.3847/2041-8213/ab1141 2041

  10. [10]

    2022, ApJL, 930, L12, doi: 10.3847/2041-8213/ac6674

    Alberdi, A., et al. 2022a, ApJL, 930, L12, doi: 10.3847/2041-8213/ac6674 Event Horizon Telescope Collaboration, Akiyama, K.,

    work page doi:10.3847/2041-8213/ac6674 2041

  11. [11]

    2022c, ApJL, 930, L17, doi: 10.3847/2041-8213/ac6756 Event Horizon Telescope Collaboration, et al

    Alberdi, A., et al. 2022b, ApJL, 930, L17, doi: 10.3847/2041-8213/ac6756

    work page doi:10.3847/2041-8213/ac6756 2041

  12. [12]

    Gammie, C. F. 2025, ApJ, 980, 193, doi: 10.3847/1538-4357/adaea3

    work page doi:10.3847/1538-4357/adaea3 2025

  13. [13]

    F., McKinney, J

    Gammie, C. F., McKinney, J. C., & Toth, G. 2003, Astrophys. J., 589, 444, doi: 10.1086/374594

    work page doi:10.1086/374594 2003

  14. [14]

    A., & Sushkov, S

    Ishkaeva, V. A., & Sushkov, S. V. 2023, PhRvD, 108, 084054, doi: 10.1103/PhysRevD.108.084054

    work page doi:10.1103/physrevd.108.084054 2023

  15. [15]

    K., Liu, C., Mizuno, Y., & Zhu, T

    Jiang, H.-X., Dihingia, I. K., Liu, C., Mizuno, Y., & Zhu, T. 2024a, JCAP, 2024, 101, doi: 10.1088/1475-7516/2024/05/101

    work page doi:10.1088/1475-7516/2024/05/101 2024

  16. [16]

    K., et al

    Jiang, H.-X., Mizuno, Y., Dihingia, I. K., et al. 2024b, A&A, 688, A82, doi: 10.1051/0004-6361/202449681

    work page doi:10.1051/0004-6361/202449681

  17. [17]

    M., & Nathanail, A

    Jiang, H.-X., Mizuno, Y., Fromm, C. M., & Nathanail, A. 2023, MNRAS, 522, 2307, doi: 10.1093/mnras/stad1106

    work page doi:10.1093/mnras/stad1106 2023

  18. [18]

    2025, arXiv e-prints, arXiv:2512.07466, doi: 10.48550/arXiv.2512.07466

    Karakonstantakis, A., & Klu´ zniak, W. 2025, arXiv e-prints, arXiv:2512.07466, doi: 10.48550/arXiv.2512.07466

    work page doi:10.48550/arxiv.2512.07466 2025

  19. [19]

    2021, PhRvD, 103, 104050, doi: 10.1103/PhysRevD.103.104050

    Kasuya, S., & Kobayashi, M. 2021, PhRvD, 103, 104050, doi: 10.1103/PhysRevD.103.104050

    work page doi:10.1103/physrevd.103.104050 2021

  20. [20]

    2021, Phys

    Simpson, A., & Visser, M. 2021, Phys. Rev. D, 103, 084052, doi: 10.1103/PhysRevD.103.084052

    work page doi:10.1103/physrevd.103.084052 2021

  21. [21]

    2021, JCAP, 04, 082, doi: 10.1088/1475-7516/2021/04/082

    Mazza, J., Franzin, E., & Liberati, S. 2021, JCAP, 04, 082, doi: 10.1088/1475-7516/2021/04/082

    work page doi:10.1088/1475-7516/2021/04/082 2021

  22. [22]

    , keywords =

    Olivares, H., Younsi, Z., Fromm, C. M., et al. 2020, MNRAS, 497, 521, doi: 10.1093/mnras/staa1878

    work page doi:10.1093/mnras/staa1878 2020

  23. [23]

    2019, ApJS, 243, 26, doi: 10.3847/1538-4365/ab29fd

    Porth, O., Chatterjee, K., Narayan, R., et al. 2019, ApJS, 243, 26, doi: 10.3847/1538-4365/ab29fd

    work page doi:10.3847/1538-4365/ab29fd 2019

  24. [24]

    Prather, B. S. 2025, KHARMA: Flexible, Portable Performance for GRMHD, doi: 10.1007/978-981-97-8522-3 5

    work page doi:10.1007/978-981-97-8522-3 2025

  25. [25]

    J., & Stone, J

    Sano, T., Inutsuka, S.-i., Turner, N. J., & Stone, J. M. 2004, ApJ, 605, 321, doi: 10.1086/382184

    work page doi:10.1086/382184 2004

  26. [26]

    2018, PhRvD, 98, 024044, doi: 10.1103/PhysRevD.98.024044

    Shaikh, R. 2018, PhRvD, 98, 024044, doi: 10.1103/PhysRevD.98.024044

    work page doi:10.1103/physrevd.98.024044 2018

  27. [28]

    2019, JCAP, 02, 042, doi: 10.1088/1475-7516/2019/02/042

    Simpson, A., & Visser, M. 2019, JCAP, 02, 042, doi: 10.1088/1475-7516/2019/02/042

    work page doi:10.1088/1475-7516/2019/02/042 2019

  28. [29]

    2025, arXiv e-prints, arXiv:2511.20756, doi: 10.48550/arXiv.2511.20756

    Suzuki, H., Mizuno, Y., Uniyal, A., et al. 2025, arXiv e-prints, arXiv:2511.20756, doi: 10.48550/arXiv.2511.20756

    work page doi:10.48550/arxiv.2511.20756 2025

  29. [30]

    2022, PhRvD, 105, 084036, doi: 10.1103/PhysRevD.105.084036

    Tsukamoto, N. 2022, PhRvD, 105, 084036, doi: 10.1103/PhysRevD.105.084036

    work page doi:10.1103/physrevd.105.084036 2022

  30. [31]

    K., & Mizuno, Y

    Uniyal, A., Dihingia, I. K., & Mizuno, Y. 2024, Astrophys. J., 970, 172, doi: 10.3847/1538-4357/ad5b5b

    work page doi:10.3847/1538-4357/ad5b5b 2024

  31. [32]

    E., P´ erez, D., & Romero, G

    Urtubey, M. E., P´ erez, D., & Romero, G. E. 2024, Eur. Phys. J. C, 84, 1163, doi: 10.1140/epjc/s10052-024-13563-2

    work page doi:10.1140/epjc/s10052-024-13563-2 2024

  32. [33]

    H., Wielgus, M., Abramowicz, M

    Vincent, F. H., Wielgus, M., Abramowicz, M. A., et al. 2021, A&A, 646, A37, doi: 10.1051/0004-6361/202037787

    work page doi:10.1051/0004-6361/202037787 2021

  33. [34]

    Shadows of Kerr-like black holes in a modified gravity theory.JCAP, 03:046, 2019.arXiv:1810.12767,doi:10.1088/1475-7516/2019/03/046

    Wang, H.-M., Xu, Y.-M., & Wei, S.-W. 2019, JCAP, 2019, 046, doi: 10.1088/1475-7516/2019/03/046

    work page doi:10.1088/1475-7516/2019/03/046 2019

  34. [35]

    N., Prather, B

    Wong, G. N., et al. 2022, Astrophys. J. Supp., 259, 64, doi: 10.3847/1538-4365/ac582e

    work page doi:10.3847/1538-4365/ac582e 2022