REVIEW 2 major objections 5 minor 55 references
For noncircular black-hole binaries in Einstein–Maxwell–dilaton theory, the angular momentum flux is now known through first post-Newtonian order, with scalar and electromagnetic dipole radiation appearing a full order before tensor quadrup
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 →
2026-08-01 16:42 UTC pith:2BWLRGRB
load-bearing objection First computation of the noncircular EMd angular momentum flux through 1PN; the physics looks right, but two printed source equations carry a c^2/γ typo that should be fixed before this goes out. the 2 major comments →
Angular momentum flux through post-Newtonian order for noncircular nonspinning black-hole binaries in Einstein-Maxwell-dilaton theory
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The paper's central result is the instantaneous angular momentum flux for generic noncircular orbits up to relative 1PN order, expressed separately for the scalar, electromagnetic, and tensor channels. The scalar dipole flux scales as O(c^-3) and is proportional to (α1−α2), the electromagnetic dipole flux also scales as O(c^-3) and is proportional to (q1/m1 − q2/m2), and the tensor quadrupole flux scales as O(c^-5); all contributions are proportional to n×v, so radiation changes the magnitude of the orbital angular momentum without tilting the orbital plane at this order. The paper demonstrates consistency with the quasicircular balance relation ΩJ_z = F, with the generic-orbit GR limit, and
What carries the argument
The calculation rests on the skeletonized point-particle action with a scalar-dependent mass expanded as m(φ) = m[1 + α δφ + ½(α²+β)δφ² + O(c^-6)], where α and β are body-dependent scalar-charge parameters. From this, the paper constructs the relaxed field equations for gravity, scalar, and electromagnetic fields, evaluates the scalar, electric, magnetic, and Epstein–Wagoner gravitational source multipole moments in the center-of-mass frame, and expands the wave-zone fields in powers of 1/R, keeping both the radiative 1/R terms and the finite-distance 1/R² terms. The angular momentum flux is then obtained by inserting the radiative fields into the scalar, electromagnetic, and Landau–Lifshitz
Load-bearing premise
The paper assumes each black hole is described by a point-particle action with a scalar-dependent mass expanded to second order and uses constant scalar-charge parameters α and β taken from an earlier matching calculation, without re-deriving them or checking whether higher-order sensitivity terms are negligible for strong-field EMd black holes; if these parameters vary during inspiral or the truncation misses important terms, the flux needs modification.
What would settle it
Compute the orbit-averaged angular momentum loss of two eccentric EMd black holes using a fully nonlinear numerical relativity simulation and compare with Eqs. (V.13)–(V.25); if the scalar/electromagnetic dipole channels do not appear at O(c^-3), or if α1 = α2 does not kill the scalar dipole flux through 1PN order, the central claim fails.
If this is right
- An orbit-averaged eccentric binary in EMd theory can be evolved using the balance equation ⟨dL/dt⟩ = −⟨J⟩, with J now known to relative 1PN order.
- Scalar and electromagnetic dipole radiation dominate angular momentum loss at a lower PN order than the gravitational quadrupole channel, making them potentially important for eccentric inspiral rates.
- The quasicircular limit of the flux satisfies ΩJ_z = F, so the new result is consistent with the previously known energy flux for circular orbits.
- In the GR limit α = β = q = 0, the scalar and electromagnetic contributions vanish and the tensor flux reduces to the known generic-orbit GR result.
- The dipole-suppression conditions α1 = α2 and q1/m1 = q2/m2 make the respective dipole contributions vanish through the order considered, confirming the expected structure.
Where Pith is reading between the lines
- If the scalar charges α and β are not truly constant during an eccentric inspiral—because the scalar field varies along the orbit or because the black-hole charges are not conserved—the flux formulas would need additional terms beyond those computed here.
- The retained 1/R² finite-distance waveform terms could be tested against numerical-relativity waveforms extracted at finite radius, where such corrections matter before taking the null-infinity limit.
- For eccentric binaries, the dipole channels at O(c^-3) may drive a qualitatively different eccentricity evolution than in GR; averaging these fluxes over an orbit is a natural next step that the paper leaves to future work.
- The α and β parameters are taken from an earlier matching calculation for EMd black holes; a direct comparison of the predicted angular-momentum loss with a fully relativistic simulation of two charged, scalar-hairy black holes would test whether the point-particle truncation is sufficient at 1PN order.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. This paper computes the instantaneous angular-momentum flux for nonspinning, noncircular black-hole binaries in Einstein-Maxwell-dilaton (EMd) theory through relative first post-Newtonian (1PN) order. Working in the Einstein frame and using the direct integration of the relaxed field equations (DIRE) approach, the authors construct the scalar, electromagnetic, and tensor fields in the wave zone, including next-to-leading 1/R² finite-distance terms, and evaluate the resulting multipole moments in the center-of-mass frame. The main results are the separate scalar, electromagnetic, and tensor contributions to the angular-momentum flux, Eqs. (V.13)-(V.25), plus a total flux. The scalar and electromagnetic channels begin at dipole order O(c^{-3}) (with the expected dipole-suppression limits when α1=α2 or q1/m1=q2/m2), while the tensor channel begins at quadrupole order O(c^{-5}). The paper reports three consistency checks: the quasicircular limit satisfies ΩJ_z=F, the GR limit recovers the known generic-orbit result, and the dipole-suppression limits are recovered.
Significance. If the final results are correct, this is a useful and nontrivial extension of post-Newtonian radiation-reaction calculations to a three-channel theory with scalar, electromagnetic, and tensor radiation. The paper is careful about PN counting, provides explicit multipole moments and waveforms, and separately documents the 1/R² wave-zone terms, which are usually omitted. The consistency checks, once verified, would give strong support to the long calculation. The main value is that the flux provides the second dissipative balance equation needed for future eccentric-orbit evolution and phasing in EMd theory. The manuscript is not machine-checked, and the differentiability of the moment algebra is not fully demonstrated, but the level of detail is appropriate for the intended audience.
major comments (2)
- [II.B, Eqs. (II.23)-(II.24)] There is an internal inconsistency in the printed matter densities. From the point-particle action (II.2), a direct variational derivative gives T^{μν}=ρ_g c²/(γ√-g) v^μ v^ν and T_φ=ρ_g γ/√-g α, with γ=c√(-g_{μν}v^μv^ν); in the rest frame γ=c². As printed, Eq. (II.23) has γ in the numerator of T^{μν}, yielding T^{00}~m c⁴δ³, and Eq. (II.24) has c²/γ, yielding T_φ~m α δ³. Both are off by a factor c² and mutually inconsistent with the action. The later source densities (e.g., μ in Eq. (III.14) and μ00 in Eq. (III.35)) use the corrected normalizations, so the final flux is probably unaffected if this is a transcription error. However, because every multipole moment in Sec. III depends on these densities, the manuscript must correct (II.23)-(II.24) and explicitly confirm that no c² factor has propagated into the derived moments and flux formulas.
- [V.D, Sec. V.D consistency checks] The three claimed consistency checks are asserted without showing the reduction. In particular, after Eq. (V.26) the paper states that the quasicircular limit of the computed flux satisfies ΩJ_z=F and agrees with Ref. [25] through 1PN order, but no comparison of the individual terms is shown. Likewise, in the GR limit the statement that the tensor flux reduces to the quadrupole and octupole results of Refs. [52,55] would benefit from explicit matching of the coefficients, especially the 1PN correction jLL_quad in Eq. (V.24). Since these checks are the primary validation of a long multipole calculation, the authors should provide enough algebra in an appendix or as a supplementary derivation for the reader to verify the reductions.
minor comments (5)
- [II.B, Eq. (II.22)] The generalized Lorentz factor γ has dimensions of c² in this convention. This is unusual and should be stated explicitly, as the later equations (II.23)-(II.24) are only dimensionally consistent once this convention is understood.
- [IV.B, Eq. (IV.15)] The quantity δ is defined in Eq. (IV.15) and used extensively in the center-of-mass reduced moments. It would aid the reader to add a sentence explaining that δ is the 1PN center-of-mass correction and that it does not carry any explicit scalar-charge dependence because the dipole condition is imposed on the total effective density μ00.
- [Appendix C, Eqs. (C.8)-(C.10)] The derivation of the angular-momentum flux formulas is compact. The definition of the transverse derivative ð_T^j and the treatment of the retarded-time implicit dependence should be stated in one or two sentences before Eq. (C.3), so the reader can follow the order-counting that drops R^{-2} terms in the flux.
- [General] The abstract and introduction refer to 'post-Newtonian order' and 'relative first post-Newtonian order' almost interchangeably. Since the scalar dipole starts at formally negative PN order relative to the tensor quadrupole, the paper should consistently use 'relative 1PN order' and state this convention near Eq. (III.4).
- [References] A few references are incomplete (e.g., Refs. [17,20,26,28,35] lack article numbers or page counts). This is a presentation issue but should be cleaned up before publication.
Circularity Check
No circularity: the angular momentum flux is computed from independent field-theory inputs and checked against external known limits.
full rationale
The derivation chain is self-contained rather than circular. The input is the point-particle action (II.2) with the scalar-mass expansion (II.3); body parameters (α_A, β_A, q_A) are taken from the external matching calculation of Ref. [27] for EMd black holes. Near-zone gravitational, scalar, and electromagnetic fields are imported from the Fokker-action derivation of Khalil et al. [25] (an independent, not self, reference), and the paper explicitly states that its own DIRE computation reproduces those fields. From these inputs the paper derives effective source densities (III.14), (III.23)–(III.24), (III.35), source multipole moments (III.15)–(III.18), (III.25)–(III.32), (III.42)–(III.45), then CM-frame moments and wave-zone fields, and finally inserts the O(R^{-1}) radiative fields into flux formulas (V.9)–(V.11). No parameter is fitted to a target angular momentum flux; no target result is used as an input. The consistency checks are genuinely external: the quasicircular limit compares the derived ΩJ_z to the energy flux of Ref. [25], the GR limit is compared to published generic-orbit results [52,55], and the dipole suppression follows algebraically from the multipole moments. The only self-citation, Ref. [21], appears in an introductory list of developments in Einstein–Maxwell–scalar theory and is not load-bearing for any derivation step. The suspected factor inconsistency in Eqs. (II.23)–(II.24) is an internal transcription/correctness concern, not circularity: later source densities such as (III.14) and (III.35) appear to use the corrected c²/γ versus γ placements, so the printed inconsistency does not reduce the final flux to an input. No circular step can be exhibited from the paper's own equations.
Axiom & Free-Parameter Ledger
free parameters (5)
- m_A (binary masses)
- q_A (electric charges)
- α_A (scalar charges)
- β_A (second-order scalar sensitivities)
- a (dilaton coupling constant)
axioms (6)
- standard math Post-Newtonian expansion and DIRE split into near-zone and wave-zone with shortwave approximation
- domain assumption The skeletonized point-particle action (II.2) with the scalar-dependent mass expansion (II.3) is a valid description of EMd black holes at 1PN
- domain assumption The scalar charges α_A and β_A are constant parameters of the bodies
- domain assumption The binary is nonspinning and the charges q_A are conserved
- standard math Wave-zone effective sources contribute only at O(R^-2) and vanish at null infinity
- standard math Harmonic gauge and Lorenz gauge can be imposed on the relaxed fields
Cite this review
Pith. "Pith review of Angular momentum flux through post-Newtonian order for noncircular nonspinning black-hole binaries in Einstein-Maxwell-dilaton theory." pith.science (2026). https://pith.science/paper/2BWLRGRB
@misc{pith2026260717887,
author = {Pith},
title = {Pith review of: Angular momentum flux through post-Newtonian order for noncircular nonspinning black-hole binaries in Einstein-Maxwell-dilaton theory},
year = {2026},
howpublished = {\url{https://pith.science/paper/2BWLRGRB}},
note = {Machine review of arXiv:2607.17887}
}
read the original abstract
We compute the instantaneous angular momentum flux from nonspinning black hole binaries in Einstein-Maxwell-dilaton theory for generic noncircular orbits up to relative first post-Newtonian order. Working in the Einstein frame and using the direct integration of the relaxed field equations approach, we construct the scalar, electromagnetic, and tensor gravitational fields in the wave zone and express the required source multipole moments in the center-of-mass frame. In addition to the leading $1/R$ radiative fields, we retain the next-to-leading $1/R^2$ terms in the wave-zone fields, which describe finite-distance corrections and do not contribute to the flux at null infinity. We obtain separately the scalar, electromagnetic, and tensor contributions to the angular momentum flux. The scalar and electromagnetic channels begin with dipole radiation, while the tensor channel begins at quadrupole order. Our results recover the quasicircular balance relation, the known general-relativistic limit, and the expected scalar- and electromagnetic-dipole suppression limits. Together with the previously known energy flux, these results provide the dissipative information required for future studies of orbit-averaged eccentric evolution and waveform phasing in Einstein-Maxwell-dilaton theory.
Figures
Reference graph
Works this paper leans on
-
[1]
B. P. Abbottet al.(LIGO Scientific, Virgo), Phys. Rev. Lett.116, 061102 (2016), arXiv:1602.03837 [gr-qc]
Pith/arXiv arXiv 2016
-
[2]
A. G. Abacet al.(LIGO Scientific, Virgo, and KAGRA Collaborations), (2026), arXiv:2605.27225 [gr-qc]
Pith/arXiv arXiv 2026
-
[3]
N. Yunes and X. Siemens, Living Rev. Rel.16, 9 (2013), arXiv:1304.3473 [gr-qc]
Pith/arXiv arXiv 2013
-
[4]
L. Blanchet, Living Rev. Rel.17, 2 (2014), arXiv:1310.1528 [gr-qc]
Pith/arXiv arXiv 2014
-
[5]
Q. Henry, F. Larrouturou, and C. Le Poncin-Lafitte, Phys. Rev. D108, 024020 (2023), arXiv:2303.17536 [gr- qc]
Pith/arXiv arXiv 2023
-
[6]
Q. Henry, F. Larrouturou, and C. Le Poncin-Lafitte, Phys. Rev. D109, 084048 (2024), arXiv:2310.03785 [gr- qc]
Pith/arXiv arXiv 2024
-
[7]
A. Bhattacharyya, S. Ghosh, and S. Pal, JHEP08, 207, arXiv:2305.15473 [hep-th]
-
[8]
T. P. Sotiriou and S.-Y. Zhou, Phys. Rev. Lett.112, 251102 (2014), arXiv:1312.3622 [gr-qc]
Pith/arXiv arXiv 2014
-
[9]
C. A. R. Herdeiro and E. Radu, Phys. Rev. Lett.112, 221101 (2014), arXiv:1403.2757 [gr-qc]. 26
Pith/arXiv arXiv 2014
-
[10]
C. A. R. Herdeiro and E. Radu, Int. J. Mod. Phys. D24, 1542014 (2015), arXiv:1504.08209 [gr-qc]
Pith/arXiv arXiv 2015
-
[11]
V. Cardoso and L. Gualtieri, Class. Quant. Grav.33, 174001 (2016), arXiv:1607.03133 [gr-qc]
Pith/arXiv arXiv 2016
-
[12]
Gibbons and K
G. Gibbons and K. ichi Maeda, Nuclear Physics B298, 741 (1988)
1988
-
[13]
Garfinkle, G
D. Garfinkle, G. T. Horowitz, and A. Strominger, Phys. Rev. D43, 3140 (1991)
1991
-
[14]
C. A. R. Herdeiro, E. Radu, N. Sanchis-Gual, and J. A. Font, Phys. Rev. Lett.121, 101102 (2018), arXiv:1806.05190 [gr-qc]
Pith/arXiv arXiv 2018
-
[15]
P. G. S. Fernandes, C. A. R. Herdeiro, A. M. Pombo, E. Radu, and N. Sanchis-Gual, Class. Quant. Grav.36, 134002 (2019), [Erratum: Class.Quant.Grav. 37, 049501 (2020)], arXiv:1902.05079 [gr-qc]
Pith/arXiv arXiv 2019
-
[16]
J. L. Bl´ azquez-Salcedo, C. A. R. Herdeiro, J. Kunz, A. M. Pombo, and E. Radu, Phys. Lett. B806, 135493 (2020), arXiv:2002.00963 [gr-qc]
Pith/arXiv arXiv 2020
-
[17]
Hod, JHEP08, 272, arXiv:2206.12074 [gr-qc]
S. Hod, JHEP08, 272, arXiv:2206.12074 [gr-qc]
-
[18]
M.-Y. Lai, Y. S. Myung, R.-H. Yue, and D.-C. Zou, Phys. Rev. D106, 044045 (2022), arXiv:2206.11587 [gr-qc]
Pith/arXiv arXiv 2022
-
[19]
M.-Y. Lai, Y. S. Myung, R.-H. Yue, and D.-C. Zou, Phys. Rev. D106, 084043 (2022), arXiv:2208.11849 [gr-qc]
Pith/arXiv arXiv 2022
-
[20]
G. Guo, P. Wang, H. Wu, and H. Yang, JHEP10, 076, arXiv:2307.12210 [gr-qc]
-
[21]
W. Xiong, C.-Y. Zhang, and P.-C. Li, JCAP09, 031, arXiv:2312.11879 [gr-qc]
-
[22]
G. W. Gibbons, Commun. Math. Phys.44, 245 (1975)
1975
-
[23]
R. D. Blandford and R. L. Znajek, Mon. Not. Roy. As- tron. Soc.179, 433 (1977)
1977
-
[24]
E. W. Hirschmann, L. Lehner, S. L. Liebling, and C. Palenzuela, Phys. Rev. D97, 064032 (2018), arXiv:1706.09875 [gr-qc]
Pith/arXiv arXiv 2018
-
[25]
M. Khalil, N. Sennett, J. Steinhoff, J. Vines, and A. Buonanno, Phys. Rev. D98, 104010 (2018), arXiv:1809.03109 [gr-qc]
Pith/arXiv arXiv 2018
-
[26]
A. Bhattacharyya, S. Ghosh, A. Mishra, and S. Pal, JHEP06, 008, arXiv:2510.07390 [hep-th]
-
[27]
Juli´ e, JCAP01, 026, arXiv:1711.10769 [gr-qc]
F.-L. Juli´ e, JCAP01, 026, arXiv:1711.10769 [gr-qc]
-
[28]
Juli´ e, JCAP10, 033, arXiv:1809.05041 [gr-qc]
F.-L. Juli´ e, JCAP10, 033, arXiv:1809.05041 [gr-qc]
-
[29]
V. De Falco and E. Battista, Phys. Rev. D108, 064032 (2023), arXiv:2309.00319 [gr-qc]
Pith/arXiv arXiv 2023
-
[30]
V. De Falco, E. Battista, D. Usseglio, and S. Capozziello, Eur. Phys. J. C84, 137 (2024), arXiv:2401.13374 [gr-qc]
Pith/arXiv arXiv 2024
-
[31]
P. C. Peters and J. Mathews, Phys. Rev.131, 435 (1963)
1963
-
[32]
P. C. Peters, Phys. Rev.136, B1224 (1964)
1964
-
[33]
K. G. Arun, L. Blanchet, B. R. Iyer, and S. Sinha, Phys. Rev. D80, 124018 (2009), arXiv:0908.3854 [gr-qc]
Pith/arXiv arXiv 2009
-
[34]
D. Trestini, Phys. Rev. D109, 104003 (2024), arXiv:2401.06844 [gr-qc]
Pith/arXiv arXiv 2024
-
[35]
A. Chowdhuri and A. Bhattacharyya, Phys. Rev. D106, 064046 (2022), arXiv:2203.09917 [gr-qc]
Pith/arXiv arXiv 2022
-
[36]
J. Samsing, Phys. Rev. D97, 103014 (2018), arXiv:1711.07452 [astro-ph.HE]
Pith/arXiv arXiv 2018
-
[37]
Epstein and R
R. Epstein and R. V. Wagoner, Astrophys. J.197, 717 (1975)
1975
-
[38]
C. M. Will and A. G. Wiseman, Phys. Rev. D54, 4813 (1996), arXiv:gr-qc/9608012
Pith/arXiv arXiv 1996
-
[39]
M. E. Pati and C. M. Will, Phys. Rev. D62, 124015 (2000), arXiv:gr-qc/0007087
Pith/arXiv arXiv 2000
-
[40]
M. E. Pati and C. M. Will, Phys. Rev. D65, 104008 (2002), arXiv:gr-qc/0201001
Pith/arXiv arXiv 2002
-
[41]
D. Astefanesei, C. Herdeiro, A. Pombo, and E. Radu, JHEP10, 078, arXiv:1905.08304 [hep-th]
Pith/arXiv arXiv 1905
-
[42]
D. M. Eardley, Astrophys. J.196, 10.1086/181744 (1975)
doi:10.1086/181744 1975
-
[43]
Poisson and C
E. Poisson and C. M. Will,Gravity: Newtonian, Post- Newtonian, Relativistic(Cambridge University Press, 2014)
2014
-
[44]
L. D. Landau and E. M. Lifschits,The Classical Theory of Fields, Course of Theoretical Physics, Vol. Volume 2 (Pergamon Press, Oxford, 1975)
1975
-
[45]
B. Shiralilou, T. Hinderer, S. M. Nissanke, N. Ortiz, and H. Witek, Class. Quant. Grav.39, 035002 (2022), arXiv:2105.13972 [gr-qc]
Pith/arXiv arXiv 2022
-
[46]
C. W. Misner, K. S. Thorne, and J. A. Wheeler,Gravi- tation(W. H. Freeman, San Francisco, 1973)
1973
-
[47]
A. D. Fokker, Zeitschrift f¨ ur Physik58, 386 (1929)
1929
-
[48]
T. Damour and G. Esposito-Farese, Phys. Rev. D53, 5541 (1996), arXiv:gr-qc/9506063
Pith/arXiv arXiv 1996
-
[49]
L. Bernard, L. Blanchet, A. Boh´ e, G. Faye, and S. Marsat, Phys. Rev. D93, 084037 (2016), arXiv:1512.02876 [gr-qc]
Pith/arXiv arXiv 2016
-
[50]
L. Bernard, Phys. Rev. D98, 044004 (2018), arXiv:1802.10201 [gr-qc]
Pith/arXiv arXiv 2018
-
[51]
X. Zhang, W. Zhao, T. Liu, K. Lin, C. Zhang, X. Zhao, S. Zhang, T. Zhu, and A. Wang, JCAP01, 019, arXiv:1811.00339 [gr-qc]
-
[52]
T. Jain and P. Rettegno, Phys. Rev. D111, 104038 (2025), arXiv:2407.10908 [gr-qc]
Pith/arXiv arXiv 2025
-
[53]
Damour and G
T. Damour and G. Esposito-Farese, Class. Quant. Grav. 9, 2093 (1992)
2093
- [54]
-
[55]
Junker and G
W. Junker and G. Sch¨ afer, Mon. Not. Roy. Astron. Soc. 254, 146 (1992)
1992
This paper was first reviewed by deepseek-v4-flash on August 1, 2026.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.