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REVIEW 4 minor 83 references

For off-shell Kerr spacetimes with a radial mass profile, a strict-convexity criterion fully classifies the possible horizon roots.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

T0 review · deepseek-v4-flash

2026-08-05 00:45 UTC pith:Y4MUPVJR

load-bearing objection A correct, narrow convexity theorem for off-shell Kerr with an honest FDM benchmark; worth a serious referee.

arxiv 2608.00519 v1 pith:Y4MUPVJR submitted 2026-08-01 gr-qc

Convexity criterion and radial-profile response for off-shell Kerr geometries: a fuzzy-dark-matter profile as an analytic benchmark

classification gr-qc MSC 83C5783C1083C75 PACS 04.70.Bw04.20.-q95.30.Sf
keywords off-shell Kerrradial mass profileconvexity criterionhorizon structurephoton sphereblack hole shadowfuzzy dark matterNewman–Janis completion
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

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

This paper establishes a sufficient condition under which the horizon structure of an off-shell Kerr spacetime, one built from a radial mass function m(r) instead of a constant total mass, is completely classified. The condition is the pointwise inequality 2m'(r) + r m''(r) < 1, together with mild positivity, monotonicity, and finite-ADM boundary limits; it makes Δ(r) = r² − 2r m(r) + a² strictly convex, so the geometry has two simple horizons, one double (extremal) horizon, or none. The theorem matters because it turns a profile-by-profile numerical root search into a certified classification: no secondary horizon branches or hidden extremal curves can exist inside the allowed domain. The authors then use a fuzzy-dark-matter-inspired soliton profile as an analytic benchmark to derive first-order responses of the outer horizon, extremal spin, photon sphere, and shadow area to general deformations m/M_ADM = 1 + εh, and show which responses are fixed by the mass profile and which depend on the arbitrary rotating completion.

Core claim

Within the one-function radial-Δ family, the paper's central claim is a convexity theorem: for any C² positive nondecreasing m(r) with m + r m' → m0 > 0 at r → 0+, m → M_ADM finite and r m' → 0 at infinity, and pointwise 2m' + r m'' < 1, the function H(r) = r − m(r) − r m'(r) is strictly increasing from a negative value to +∞, hence vanishes exactly once; consequently Δ'' = 2H' > 0 and Δ is strictly convex with a unique positive minimum. For a ≠ 0, the sign of that minimum decides between two simple positive roots, one double root, or no root; for a = 0 there is exactly one simple positive root after excluding the origin. The FDM-inspired profile satisfies the hypotheses whenever f_sol/(r_c/

What carries the argument

The load-bearing object is H(r) = r − m(r) − r m'(r), one half of Δ'(r). The proof hinges on the identity H'(r) = 1 − 2m'(r) − r m''(r): the pointwise bound makes H strictly increasing, and the central and asymptotic limits force it to cross zero exactly once. This single monotone-crossing argument carries all root-count, extremality, and completeness statements. For the response theory, the organizing device is the deformation μ(x; ε) = 1 + εh(x) with h → 0 at infinity; first-order coefficients for the outer horizon, extremal spin, static photon sphere, and critical impact parameters are expressed directly through local values of h and h', with the shadow area treated through an endpoint-re

Load-bearing premise

The fragile premise is that the mass profile has a finite ADM limit with r m'(r) → 0 at infinity while remaining monotone and satisfying the pointwise derivative bound; realistic profiles such as the untruncated NFW profile are logarithmically divergent and fall outside the theorem, leaving open the possibility of extra roots there.

What would settle it

Build a smooth, positive, nondecreasing C² mass function m(r) that satisfies m + r m' → m0 > 0 at r → 0+, m → finite M_ADM, r m' → 0 at infinity, and 2m' + r m'' < 1 everywhere, and compute H(r) = r − m − r m'. If H has more than one positive zero for some such m, the strict-convexity theorem is false; a numerical random search over such profiles, or an explicit counterexample with an admissible but sharply varying derivative, would settle it. The paper's own smooth-shell example rules out only the converse (monotonicity without the derivative bound), so it does not test this case.

Watch this falsifier. Get emailed when new claim-graph text bears on it.

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If this is right

  • For any profile inside the theorem's domain, horizon classification is exhaustive: two simple roots, one double root, or none (one positive root when a = 0), so a numerically missed secondary horizon cannot occur.
  • The constant-mass replacement m(r) → M_ADM returns Kerr exactly and eliminates all radial-profile response; it is a reference baseline, not an approximation to a distributed environment.
  • At first order in the environmental fraction, the outer horizon, extremal spin, and static photon sphere are determined by local values of h and h' at the unperturbed radii; the area-equivalent shadow radius follows with endpoint motion included.
  • Spin-odd shadow displacement is not fixed by the mass profile alone: the slow-rotation comparison yields a displacement band at O(a), with half-widths around 0.017–0.043 M_ADM at f_sol = 0.1–0.2 and j_ADM = 0.2.
  • In a physically scaled weak-field FDM example the true profile-gradient effect is below 10⁻²⁰; percent-level deviations at fixed ADM mass are charge-normalization effects, so the compact benchmark must not be read as a self-consistent rotating scalar-field solution.

Where Pith is reading between the lines

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

  • Beyond the paper: the theorem's proof depends only on one-variable Δ and monotonicity of H, so the same root classification should transfer to other off-shell Kerr–Schild or regular rotating families satisfying the hypotheses, regardless of how the matter closure was chosen.
  • Beyond the paper: the first-order response formulas are invertible in principle—measured horizon and shadow-area shifts as functions of environmental fraction could constrain m(r) near the photon sphere independently of the total ADM mass.
  • Beyond the paper: applying the criterion to truncated NFW or Einasto profiles would map where extra-horizon branches appear once the infinite-mass failure of untruncated NFW is removed.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

0 major / 4 minor

Summary. The paper studies off-shell Kerr geometries specified by a radial mass function m(r) through Δ(r)=r²−2rm(r)+a². Its central result is a sufficient convexity theorem (Sec. V.A): for a positive, nondecreasing C² mass function satisfying the central limit m+r m′→m₀>0, the finite-ADM limits m→M_ADM and r m′→0, and the pointwise bound 2m′+r m″<1, the function H=r−m−r m′ is strictly increasing, so Δ is strictly convex and has a unique positive minimum. This yields a complete root trichotomy for a≠0 (two simple roots, one double root, or none) and exactly one physical positive root in the static case. The theorem is applied to an FDM-inspired compact profile with a closed-form mass integral, giving an analytic domain f_sol/(r_c/M_ADM)<0.691428 that covers the production box. The paper then derives first-order response formulas for horizons, the extremal branch, photon orbits, and the shadow under m/M_ADM=1+εh, and compares them with full-profile numerics and constant-mass Kerr. It also quantifies Newman–Janis completion dependence of spin-odd shadow displacements and repeatedly emphasizes that the geometry is an effective benchmark, not a self-consistent Einstein–Klein–Gordon solution.

Significance. If accepted, the convexity theorem is a clean and portable classification tool for horizon topology in the one-function radial-Δ family. The proof is self-contained and correct: H′>0 makes H strictly increasing, and the boundary limits fix exactly one zero, giving the stated root behavior. The paper’s strengths include its explicit scope mapping (the theorem is sufficient, not necessary, and the untruncated NFW profile is correctly placed outside the domain), the inclusion of counterexamples such as the smooth shell with four roots, extensive numerical audits (2976 all-branch and 1736 perturbative-error configurations with documented convergence), and symbolic consistency checks of the inverse metric, determinant, and Kretschmann scalar. The first-order response formulas are internally consistent with the unexpanded equations, and the numerical derivatives are reported with conservative error budgets. The authors are unusually careful to separate general off-shell results from profile-specific and completion-dependent claims, which makes the benchmark character of the FDM application clear.

minor comments (4)
  1. [Acknowledgments] Typo: “The authors gratefully acknowledges” should be “The authors gratefully acknowledge”.
  2. [Appendix B / CAS scripts] The text refers to an “accompanying open CAS script kretschmann_cas.wl” and a “distributed script”, but no URL, repository, or ancillary-file listing is given. If these scripts are intended to support the reproducibility claim, please provide access information or attach them.
  3. [Sec. V.A / Eq. (194)] The central-limit hypothesis is stated as a combined limit. It would help the reader to add one sentence noting that monotonicity plus this limit implies m(0+)=m₀ and r m′(r)→0, which is what justifies Δ(0+)=a² in the root trichotomy. The proof is sound, but this step is implicit.
  4. [Sec. II.B / Eq. (35)] In the physical scaling example, “rc = 3GMADM/c2 ≃6.38×10⁻⁷ pc” is notationally awkward; writing r_c = 3GM_ADM/c² would avoid confusion with the core-radius symbol and the exponent.

Circularity Check

0 steps flagged

No significant circularity: the convexity theorem, corollary, and response formulas are derived from stated assumptions via direct calculus, not from fitted parameters or self-citations.

full rationale

The central claim (Sec. V A) is self-contained: H'(r)=1-2m'-rm''>0 makes H strictly increasing; the central limit gives H(0+)=-m0<0 and the asymptotic conditions give H(r)->r-M_ADM>0, so H has exactly one zero and Delta is strictly convex. The root trichotomy then follows from the sign of Delta at the unique minimum; the static a=0 case is handled by excluding the coordinate factor root. None of these definitions or assumptions is stated in terms of the conclusion, and the theorem does not depend on the FDM profile. The FDM-inspired corollary is obtained by explicitly maximizing Q(y) for the closed-form profile, giving f_sol/(r_c/M_ADM)<0.691428; this is an analytic sufficient domain, not a fit. The first-order response identities in Sec. VII are ordinary Taylor coefficients of the same unexpanded horizon, extremal, photon-sphere, and shadow equations, with h(x) an arbitrary C^2 deformation satisfying h(infinity)=0; they are not fitted to the quantities they predict. The spin-odd shadow displacement is explicitly labeled completion-dependent and the slow-rotation family omega_kappa is presented as a diagnostic band, not as a unique prediction. The paper repeatedly states its limitations (not an Einstein-Klein-Gordon solution, compact profile not an unperturbed FDM core, constant-mass replacement only a Kerr reference, WEC is an effective-source sign diagnostic). The finite-ADM restriction explicitly excludes untruncated NFW (Table III), which is presented as a scope boundary, not as evidence for the theorem. References to prior work such as the FDM density profile [3,4] and source-based environments [12,13] are external inputs or contingent comparisons, not load-bearing self-citations; the bibliography contains no self-citations by the author set. Therefore the derivation chain is not circular within the explicitly stated ansatz; score 0.

Axiom & Free-Parameter Ledger

4 free parameters · 4 axioms · 1 invented entities

The central claim rests on the standard assumptions of general relativity (Einstein equations, energy conditions) and a series of modeling assumptions stated in the paper: the static Schwarzschild-gauge closure g_tt g_rr = -1, the Newman-Janis complexification rule, and the FDM-inspired density profile shape. The free parameters fsol and rc/MADM are scanned, not fitted. The paper is careful to flag the effective nature of the geometry.

free parameters (4)
  • fsol = Msol/MADM = not fitted; explored as 0..0.30
    The total soliton mass fraction is a variable parameter of the model, not determined by the theory. It is scanned over a range rather than fitted to data.
  • rc/MADM (core radius scale) = rc/MADM in {2,3,5,10}
    The core radius scale is a free parameter of the FDM-inspired profile, scanned over a range. It is not fixed by the paper's own equations from first principles.
  • rho_c (central density) = related to Msol and rc via Eq. (30)
    The central density is a parameter of the density profile (Eq. 17). The paper uses the isolated-soliton scaling relation (Eq. 33) from the literature to connect it to the boson mass m_phi, but the scaling relation is cited, not derived.
  • m_phi (boson mass) = 10^-19 eV and 8.9x10^-17 eV in examples
    The boson mass enters through the FDM scaling relation (Eq. 33). It is not fitted to data in this paper; it is used as an input parameter in the weak-field example.
axioms (4)
  • domain assumption The Newman-Janis complexification prescription with m(r) evaluated at Re r (Sec. III) yields a valid effective metric with the stated asymptotic charges.
    The rotating metric is constructed via a specific Newman-Janis prescription. The paper correctly notes that this is not unique and not a self-consistent scalar-field solution; the metric is an ansatz.
  • domain assumption The null Hamilton-Jacobi equation separates with a Carter-like constant for the chosen rotating metric.
    The paper verifies the separability algebraically in Appendix B, but this is a structural property of the selected completion, not a generic prediction for rotating matter environments.
  • domain assumption The FDM profile shape (Eq. 17) is a valid representation of the soliton core from fuzzy dark matter simulations.
    The density profile is motivated by cited Schr-dinger-Poisson simulations. The paper explicitly disclaims that its compact parameter box represents an astrophysical FDM core, so the profile is used as a formal benchmark.
  • domain assumption The isolated-soliton scaling relations (Eqs. 33, 34) map physical FDM parameters to core radius and mass.
    These relations are cited from the literature. The paper uses them in the weak-field example to estimate physical scales, but does not derive them.
invented entities (1)
  • No new fundamental entities no independent evidence
    purpose: The WEC boundary, extremal branch, and photon-region structures are derived quantities, not new physical objects.
    The paper introduces no new particle, force, dimension, or conserved quantity. It studies known structures in a parametrized metric. The effective rotating geometry is an ansatz, but it is not presented as a fundamental solution.

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Cite this review

Pith. "Pith review of Convexity criterion and radial-profile response for off-shell Kerr geometries: a fuzzy-dark-matter profile as an analytic benchmark." pith.science (2026). https://pith.science/paper/Y4MUPVJR

@misc{pith2026260800519,
  author       = {Pith},
  title        = {Pith review of: Convexity criterion and radial-profile response for off-shell Kerr geometries: a fuzzy-dark-matter profile as an analytic benchmark},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/Y4MUPVJR}},
  note         = {Machine review of arXiv:2608.00519}
}
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read the original abstract

We establish a sufficient one-minimum criterion for the off-shell Kerr family $\Delta(r) = r^2 - 2rm(r) + a^2$ with a positive, nondecreasing mass profile $m(r)$, showing that $1 - 2m'(r) - rm''(r) > 0$ ensures strict convexity and determines root counts for $\Delta$. Using a fuzzy-dark-matter-inspired benchmark satisfying this bound, we derive first-order responses for the outer horizon, extremal branch, photon sphere, and shadow functional under general deformations $m/M_{\text{ADM}} = 1 + \varepsilon h$. We demonstrate that static horizon and photon responses are profile-controlled, spin-odd shadow displacements are completion-dependent, and scale-consistent weak-field limits render local profile-gradient effects negligible ($\ll 10^{-20}$), confirming the strong-field box as a formal radial-profile benchmark rather than a self-consistent rotating scalar-field solution.

Figures

Figures reproduced from arXiv: 2608.00519 by Jie Shi, Jingxu Wu, Liangyu Luo.

Figure 1
Figure 1. Figure 1: FIG. 1. Asymptotic normalization and radial rotational response of the FDM-inspired Kerr-like geometry. Panel (a) shows [PITH_FULL_IMAGE:figures/full_fig_p011_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Weak-energy-condition structure of the rotating effective source. Panel (a) shows the normalized angular factor [PITH_FULL_IMAGE:figures/full_fig_p016_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Horizon structure, extremality, and the combined sign-based effective-source consistency domain of the FDM-inspired [PITH_FULL_IMAGE:figures/full_fig_p021_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Photon spheres, unstable spherical photon orbits, and critical impact parameters within the selected Newman–Janis [PITH_FULL_IMAGE:figures/full_fig_p025_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Modification of the black-hole shadow relative to a Kerr spacetime with the same ADM mass and ADM angular [PITH_FULL_IMAGE:figures/full_fig_p026_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6. Comparison among the full radial-profile calculation within the selected effective ansatz, the first-order perturbative [PITH_FULL_IMAGE:figures/full_fig_p030_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: FIG. 7. Absolute relative first-order errors over 1,736 audited configurations at [PITH_FULL_IMAGE:figures/full_fig_p031_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: FIG. 8. Representative exterior root functions for the most near-extremal audited slice, [PITH_FULL_IMAGE:figures/full_fig_p039_8.png] view at source ↗

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Reference graph

Works this paper leans on

83 extracted references · 19 canonical work pages · 5 internal anchors

  1. [1]

    percent accuracy

    A stronger consistency condition is ε x(0) + h(x(0) + ) x(0) + −1 ≪x (0) + .(319) 28 For the extremal configuration, let xe = 1 +εx (1) e +O(ε 2).(320) Expansion of Eq. (233) yields x(1) e =h(1) +h ′(1).(321) Substitution into Eq. (234) gives j2 ext = 1 + 2εh(1) +O(ε 2),(322) and hence jext = 1 +εh(1) +O(ε 2).(323) The terms involvingh ′(1) cancel from th...

  2. [2]

    Each sign-changing interval is then refined with Brent’s method

    Horizon and extremality algorithms The dimensionless horizon function is b∆(x) =x 2 −2xµ(x) +j 2 ADM.(D6) Positive roots are first bracketed on a combined logarith- mic and linear radial grid. Each sign-changing interval is then refined with Brent’s method. Duplicate roots closer than the root tolerance are discarded, andallpositive roots are retained bef...

  3. [3]

    Adaptive quadrature reports an area error below 5×10 −13M 2 ADM, corresponding to less than 2×10 −8 in thes= 10 −6 difference quotient

    Perturbative coefficients The first-order corrections to the horizon, extremal spin, and static photon sphere are evaluated from the analytical expressions x(1) + = x(0) + h(x(0) + ) x(0) + −1 ,(D31) j(1) ext =h(1),(D32) and x(1) ph = 3 [h(3)−h ′(3)].(D33) For the shadow area radius, lets >0 denote a numerical step inf sol, distinct from the profile funct...

  4. [4]

    Their ordered union par- titions the exterior radial domain; a subinterval is re- tained only when its midpoint satisfies both Eqs

    Photon-region and shadow algorithms For each subextremal configuration, the spherical-orbit impact parameters are evaluated from ξc(xp) = (x2 p +j 2 ADM) b∆′ −4x p b∆ jADM b∆′ ,(D13) ηc(xp) = 16x2 p b∆ ( b∆′)2 −(ξ c −j ADM)2.(D14) The initial radial scan begins immediately outside the outer horizon, xp,min =x +(1 +ϵ h),(D15) with ϵh = 10−6.(D16) The visib...

  5. [5]

    D. J. E. Marsh, Axion cosmology, Phys. Rep.643, 1 (2016), arXiv:1510.07633

  6. [6]

    Convergence test As a representative convergence test, consider fsol = 0.10,br c = 3, j ADM = 0.70, ι= 60 ◦. (D36) The outer horizon is x+ = 1.4756379397.(D37) 39 10−8 10−6 10−4 10−2 100 (xp − x + )/MADM −1.00 −0.75 −0.50 −0.25 0.00 0.25 0.50 0.75 1.00 normalized root function rc/MADM = 2, fsol = 0.30, j/jext = 0.999 Q/S Q00/S00 10−8 10−6 10−4 10−2 10...

  7. [7]

    W. Hu, R. Barkana, and A. Gruzinov, Fuzzy cold dark matter: The wave properties of ultralight particles, Phys. Rev. Lett.85, 1158 (2000), arXiv:astro-ph/0003365

  8. [8]

    P. J. E. Peebles, Fluid dark matter, Astrophys. J. Lett. 534, L127 (2000), arXiv:astro-ph/0002495

  9. [9]

    Schive, T

    H.-Y. Schive, T. Chiueh, and T. Broadhurst, Cosmic structure as the quantum interference of a coherent dark wave, Nat. Phys.10, 496 (2014), arXiv:1406.6586

  10. [10]

    Schive, M.-H

    H.-Y. Schive, M.-H. Liao, T.-P. Woo, S.-K. Wong, T. Chi- ueh, T. Broadhurst, and W.-Y. P. Hwang, Understand- ing the core–halo relation of quantum wave dark mat- ter from three-dimensional simulations, Phys. Rev. Lett. 113, 261302 (2014), arXiv:1407.7762

  11. [11]

    Cardoso and P

    V. Cardoso and P. Pani, Testing the nature of dark com- pact objects: A status report, Living Rev. Relativ.22, 4 (2019), arXiv:1904.05363

  12. [12]

    L. Hui, J. P. Ostriker, S. Tremaine, and E. Witten, Ul- tralight scalars as cosmological dark matter, Phys. Rev. D95, 043541 (2017), arXiv:1610.08297

  13. [13]

    Hui, Wave dark matter, Annu

    L. Hui, Wave dark matter, Annu. Rev. Astron. Astro- phys.59, 247 (2021), arXiv:2101.11735

  14. [14]

    E. Y. Davies and P. Mocz, Fuzzy dark matter soliton cores around supermassive black holes, Mon. Not. R. As- tron. Soc.492, 5721 (2020), arXiv:1908.04790

  15. [15]

    Cardoso, T

    V. Cardoso, T. Ikeda, R. Vicente, and M. Zilh˜ ao, Par- asitic black holes: The swallowing of a fuzzy dark matter soliton, Phys. Rev. D106, L121302 (2022), arXiv:2207.09469

  16. [16]

    Barausse, V

    E. Barausse, V. Cardoso, and P. Pani, Can environmental effects spoil precision gravitational-wave astrophysics?, Phys. Rev. D89, 104059 (2014), arXiv:1404.7149

  17. [17]

    Destounis and P

    K. Destounis and P. G. S. Fernandes, Environmentally induced chaos: Extreme-mass-ratio systems of rotating black holes in astrophysical environments, Phys. Rev. D 113, 044040 (2026), arXiv:2508.20191

  18. [18]

    Datta and C

    S. Datta and C. Singha, Geometric properties of slowly rotating black holes embedded in matter environments, Phys. Rev. D113, 124052 (2026), arXiv:2602.10579

  19. [19]

    D. S. Fonseca, C. F. B. Macedo, M. M. Corrˆ ea, and D. Rubiera-Garcia, Matter environments around black holes: Geodesics, light rings, and ultracom- pact configurations, Phys. Rev. D113, 124039 (2026), arXiv:2512.22267

  20. [20]

    Cardoso, K

    V. Cardoso, K. Destounis, F. Duque, R. Panosso Macedo, and A. Maselli, Black holes in galaxies: En- vironmental impact on gravitational-wave generation and propagation, Phys. Rev. D105, L061501 (2022), arXiv:2109.00005

  21. [21]

    Datta, Black holes immersed in dark matter: Energy condition and sound speed, Phys

    S. Datta, Black holes immersed in dark matter: Energy condition and sound speed, Phys. Rev. D109, 104042 (2024), arXiv:2312.01277

  22. [22]

    P. G. S. Fernandes and V. Cardoso, Spinning black holes in astrophysical environments, Phys. Rev. Lett.135, 211403 (2025), arXiv:2507.04389. 41

  23. [23]

    S. P. Drake and P. Szekeres, Uniqueness of the Newman– Janis algorithm in generating the Kerr–Newman metric, Gen. Relativ. Gravit.32, 445 (2000)

  24. [24]

    Identifying the Event Horizons of Parametrically Deformed Black-Hole Metrics

    D. Heumann and D. Psaltis, Identifying the event horizons of parametrically deformed black-hole metrics, Phys. Rev. D107, 044015 (2023), arXiv:2205.12994

  25. [25]

    R. P. Kerr, Gravitational field of a spinning mass as an example of algebraically special metrics, Phys. Rev. Lett. 11, 237 (1963)

  26. [26]

    J. B. Hartle, Slowly rotating relativistic stars. I. Equa- tions of structure, Astrophys. J.150, 1005 (1967)

  27. [27]

    J. B. Hartle and K. S. Thorne, Slowly rotating relativistic stars. II. Models for neutron stars and supermassive stars, Astrophys. J.153, 807 (1968)

  28. [28]

    E. T. Newman and A. I. Janis, Note on the Kerr spinning- particle metric, J. Math. Phys.6, 915 (1965)

  29. [29]

    Chandrasekhar,The Mathematical Theory of Black Holes(Oxford University Press, Oxford, 1983)

    S. Chandrasekhar,The Mathematical Theory of Black Holes(Oxford University Press, Oxford, 1983)

  30. [30]

    Bambi and L

    C. Bambi and L. Modesto, Rotating regular black holes, Phys. Lett. B721, 329 (2013), arXiv:1302.6075

  31. [31]

    Azreg-A ¨ ınou, Generating rotating regular black hole solutions without complexification, Phys

    M. Azreg-A ¨ ınou, Generating rotating regular black hole solutions without complexification, Phys. Rev. D90, 064041 (2014), arXiv:1405.2569

  32. [32]

    Toshmatov, B

    B. Toshmatov, B. Ahmedov, A. Abdujabbarov, and Z. Stuchl ´ ık, Rotating regular black hole solution, Phys. Rev. D89, 104017 (2014), arXiv:1404.6443

  33. [33]

    Carter, Hamilton–Jacobi and Schr¨ odinger separable solutions of Einstein’s equations, Commun

    B. Carter, Hamilton–Jacobi and Schr¨ odinger separable solutions of Einstein’s equations, Commun. Math. Phys. 10, 280 (1968)

  34. [34]

    J. M. Bardeen, Timelike and null geodesics in the Kerr metric, inBlack Holes, edited by C. DeWitt and B. S. De- Witt (Gordon and Breach, New York, 1973), pp. 215– 239

  35. [35]

    Akiyamaet al.(Event Horizon Telescope Collabo- ration), First M87 Event Horizon Telescope results

    K. Akiyamaet al.(Event Horizon Telescope Collabo- ration), First M87 Event Horizon Telescope results. I. The shadow of the supermassive black hole, Astrophys. J. Lett.875, L1 (2019), arXiv:1906.11238

  36. [36]

    R. M. Wald,General Relativity(University of Chicago Press, Chicago, 1984)

  37. [37]

    Poisson,A Relativist’s Toolkit: The Mathematics of Black-Hole Mechanics(Cambridge University Press, Cambridge, 2004)

    E. Poisson,A Relativist’s Toolkit: The Mathematics of Black-Hole Mechanics(Cambridge University Press, Cambridge, 2004)

  38. [38]

    P. V. P. Cunha and C. A. R. Herdeiro, Shadows and strong gravitational lensing: A brief review, Gen. Rela- tiv. Gravit.50, 42 (2018), arXiv:1801.00860

  39. [39]

    S. E. Gralla, D. E. Holz, and R. M. Wald, Black hole shadows, photon rings, and lensing rings, Phys. Rev. D 100, 024018 (2019), arXiv:1906.00873

  40. [40]

    Perlick and O

    V. Perlick and O. Yu. Tsupko, Calculating black hole shadows: Review of analytical studies, Phys. Rep.947, 1 (2022), arXiv:2105.07101

  41. [41]

    Barcel´ o and M

    C. Barcel´ o and M. Visser, Scalar fields, energy conditions, and traversable wormholes, Class. Quantum Grav.17, 3843 (2000), arXiv:gr-qc/0003025

  42. [42]

    Akiyamaet al.(Event Horizon Telescope Collabora- tion), First M87 Event Horizon Telescope results

    K. Akiyamaet al.(Event Horizon Telescope Collabora- tion), First M87 Event Horizon Telescope results. VI. The shadow and mass of the central black hole, Astrophys. J. Lett.875, L6 (2019), arXiv:1906.11243

  43. [43]

    Akiyamaet al.(Event Horizon Telescope Collabora- tion), First Sagittarius A* Event Horizon Telescope re- sults

    K. Akiyamaet al.(Event Horizon Telescope Collabora- tion), First Sagittarius A* Event Horizon Telescope re- sults. I. The shadow of the supermassive black hole in the center of the Milky Way, Astrophys. J. Lett.930, L12 (2022)

  44. [44]

    Akiyamaet al.(Event Horizon Telescope Collabora- tion), First Sagittarius A* Event Horizon Telescope re- sults

    K. Akiyamaet al.(Event Horizon Telescope Collabora- tion), First Sagittarius A* Event Horizon Telescope re- sults. VI. Testing the black hole metric, Astrophys. J. Lett.930, L17 (2022), arXiv:2311.09484

  45. [45]

    S. W. Hawking and G. F. R. Ellis,The Large Scale Struc- ture of Space-Time(Cambridge University Press, Cam- bridge, 1973)

  46. [46]

    Visser,Lorentzian Wormholes: From Einstein to Hawking(American Institute of Physics, Woodbury, New York, 1996)

    M. Visser,Lorentzian Wormholes: From Einstein to Hawking(American Institute of Physics, Woodbury, New York, 1996)

  47. [47]

    Veltmaat, J

    J. Veltmaat, J. C. Niemeyer, and B. Schwabe, Formation and structure of ultralight bosonic dark matter halos, Phys. Rev. D98, 043509 (2018), arXiv:1804.09647

  48. [48]

    L. M. Widrow and N. Kaiser, Using the Schr¨ odinger equation to simulate collisionless matter, Astrophys. J. Lett.416, L71 (1993)

  49. [49]

    Matos and L

    T. Matos and L. A. Ure˜ na-L´ opez, Quintessence and scalar dark matter in the Universe, Class. Quantum Grav.17, L75 (2000), arXiv:astro-ph/0004332

  50. [50]

    V. H. Robles and T. Matos, Flat central density profile and constant dark matter surface density in galaxies from scalar field dark matter, Mon. Not. R. Astron. Soc.422, 282 (2012), arXiv:1201.3032

  51. [51]

    D. J. E. Marsh and A.-R. Pop, Axion dark matter, soli- tons and the cusp–core problem, Mon. Not. R. Astron. Soc.451, 2479 (2015), arXiv:1502.03456

  52. [52]

    P. Mocz, M. Vogelsberger, V. H. Robles, J. Zavala, M. Boylan-Kolchin, A. Fialkov, and L. Hernquist, Galaxy formation with BECDM. I. Turbulence and relaxation of idealized haloes, Mon. Not. R. Astron. Soc.471, 4559 (2017), arXiv:1705.05845

  53. [53]

    May and V

    S. May and V. Springel, Structure formation in large- volume cosmological simulations of fuzzy dark matter: Impact of the non-linear dynamics, Mon. Not. R. Astron. Soc.506, 2603 (2021), arXiv:2101.01828

  54. [54]

    N. Bar, D. Blas, K. Blum, and S. Sibiryakov, Galactic rotation curves versus ultralight dark matter: Implica- tions of the soliton–host halo relation, Phys. Rev. D98, 083027 (2018), arXiv:1805.00122

  55. [55]

    Schwabe, J

    B. Schwabe, J. C. Niemeyer, and J. F. Engels, Simula- tions of solitonic core mergers in ultralight axion dark matter cosmologies, Phys. Rev. D94, 043513 (2016), arXiv:1606.05151

  56. [56]

    D. G. Levkov, A. G. Panin, and I. I. Tkachev, Gravita- tional Bose–Einstein condensation in the kinetic regime, Phys. Rev. Lett.121, 151301 (2018), arXiv:1804.05857

  57. [57]

    Eggemeier and J

    B. Eggemeier and J. C. Niemeyer, Formation and mass growth of axion stars in axion miniclusters, Phys. Rev. D100, 063528 (2019), arXiv:1906.01348

  58. [58]

    Moczet al., First star-forming structures in fuzzy cosmic filaments, Phys

    P. Moczet al., First star-forming structures in fuzzy cosmic filaments, Phys. Rev. Lett.123, 141301 (2019), arXiv:1910.01653

  59. [59]

    J. C. S. Neves and A. Saa, Regular rotating black holes and the weak energy condition, Phys. Lett. B734, 44 (2014), arXiv:1402.2694

  60. [60]

    H. Y. J. Chan, E. G. M. Ferreira, S. May, K. Hayashi, and M. Chiba, The diversity of core–halo structure in the fuzzy dark matter model, Mon. Not. R. Astron. Soc. 511, 943 (2022), arXiv:2110.11882

  61. [61]

    G¨ urses and F

    M. G¨ urses and F. G¨ ursey, Lorentz covariant treatment of the Kerr–Schild geometry, J. Math. Phys.16, 2385 (1975)

  62. [62]

    Dymnikova, Spherically symmetric space-time with regular de Sitter center, Int

    I. Dymnikova, Spherically symmetric space-time with regular de Sitter center, Int. J. Mod. Phys. D12, 1015 42 (2003), arXiv:gr-qc/0304110

  63. [63]

    S. A. Hayward, Formation and evaporation of nonsin- gular black holes, Phys. Rev. Lett.96, 031103 (2006), arXiv:gr-qc/0506126

  64. [64]

    V. P. Frolov, Notes on nonsingular models of black holes, Phys. Rev. D94, 104056 (2016), arXiv:1609.01758

  65. [65]

    V. P. Frolov and D. Kubizˇ n´ ak, Hidden symmetries of higher dimensional rotating black holes, Phys. Rev. Lett. 98, 011101 (2007), arXiv:gr-qc/0605058

  66. [66]

    Toshmatov, Z

    B. Toshmatov, Z. Stuchl ´ ık, and B. Ahmedov, Generic rotating regular black holes in general relativity coupled to nonlinear electrodynamics, Phys. Rev. D95, 084037 (2017), arXiv:1704.07300

  67. [67]

    Beltracchi and P

    P. Beltracchi and P. Gondolo, Physical interpretation of Newman–Janis rotating systems. I. A unique family of Kerr–Schild systems, Phys. Rev. D104, 124066 (2021), arXiv:2104.02255

  68. [68]

    Physical interpretation of Newman-Janis rotating systems. II. General systems

    P. Beltracchi and P. Gondolo, Physical interpretation of Newman–Janis rotating systems. II. General systems, Phys. Rev. D104, 124067 (2021), arXiv:2108.02841

  69. [69]

    Simpson and M

    A. Simpson and M. Visser, The eye of the storm: A regular Kerr black hole, J. Cosmol. Astropart. Phys.03 (2022) 011, arXiv:2111.12329

  70. [70]

    Benenti and M

    S. Benenti and M. Francaviglia, Remarks on certain sep- arability structures and their applications to general rel- ativity, Gen. Relativ. Gravit.10, 79 (1979)

  71. [71]

    Grenzebach, V

    A. Grenzebach, V. Perlick, and C. L¨ ammerzahl, Photon regions and shadows of Kerr–Newman–NUT black holes with a cosmological constant, Phys. Rev. D89, 124004 (2014), arXiv:1403.5234

  72. [72]

    Krtouˇ s, D

    P. Krtouˇ s, D. Kubizˇ n´ ak, D. N. Page, and V. P. Frolov, Killing–Yano tensors, rank-2 Killing tensors, and con- served quantities in higher dimensions, J. High Energy Phys.02(2007) 004, arXiv:hep-th/0612029

  73. [73]

    Closed conformal Killing-Yano tensor and Kerr-NUT-de Sitter spacetime uniqueness

    T. Houri, T. Oota, and Y. Yasui, Closed conformal Killing–Yano tensor and Kerr–NUT–de Sitter space- time uniqueness, Phys. Lett. B656, 214 (2007), arXiv:0708.1368

  74. [74]

    V. P. Frolov, P. Krtouˇ s, and D. Kubizˇ n´ ak, Black holes, hidden symmetries, and complete integrability, Living Rev. Relativ.20, 6 (2017), arXiv:1705.05482

  75. [75]

    Johannsen, Regular black hole metric with three constants of motion, Phys

    T. Johannsen, Regular black hole metric with three constants of motion, Phys. Rev. D88, 044002 (2013), arXiv:1501.02809

  76. [76]

    R. A. Konoplya, L. Rezzolla, and A. Zhidenko, Gen- eral parametrization of axisymmetric black holes in met- ric theories of gravity, Phys. Rev. D93, 064015 (2016), arXiv:1602.02378

  77. [77]

    R. A. Konoplya, Shadow of a black hole surrounded by dark matter, Phys. Lett. B795, 1 (2019), arXiv:1905.00064

  78. [78]

    R. C. Pantig and A. ¨Ovg¨ un, Black hole in quantum wave dark matter, Fortschr. Phys.71, 2200164 (2023), arXiv:2210.00523

  79. [79]

    Z. Xu, X. Hou, and J. Wang, Kerr–anti-de Sitter/de Sitter black hole in perfect fluid dark matter back- ground, Class. Quantum Grav.35, 115003 (2018), arXiv:1711.04538

  80. [80]

    X. Hou, Z. Xu, and J. Wang, Rotating black hole shadow in perfect fluid dark matter, J. Cosmol. Astropart. Phys. 12(2018) 040, arXiv:1810.06381

Showing first 80 references.