REVIEW 2 major objections 6 minor 38 references
From the one-loop gravitational bremsstrahlung waveform, the paper extracts the spectral radiance, energy spectrum, angular distribution to G^{4} and the nonlinear-memory multipoles to G^{5} at fractional 7.5PN accuracy in the center-of-mas
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 · grok-4.5
2026-07-11 23:16 UTC pith:KCGDRX2A
load-bearing objection Solid high-order post-processing of the known one-loop bremsstrahlung waveform: new CM-frame multipoles for spectrum, angular distribution and nonlinear memory at 7.5PN, with clean checks against known totals. the 2 major comments →
Radiated Energy Spectrum, Radiated Angular Distribution and Non-linear Memory from the One-loop Gravitational Bremsstrahlung Waveform
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Given the one-loop-accurate frequency-domain gravitational waveform for two-body scattering, the spectral GW radiance, the radiated energy spectrum dE^{+}_gw/dω and the radiated angular distribution dE_gw/dΩ can be obtained to order G^{4}, and the multipole coefficients of the nonlinear memory can be obtained to order G^{5}, all at fractional 7.5PN accuracy in the center-of-mass frame.
What carries the argument
The spectral radiance constructed from the squared one-loop frequency-domain waveform, which is then integrated over angles or frequencies and decomposed into spherical harmonics; the resulting E_lm multipoles convert directly into the spin-weighted multipoles of the nonlinear memory via a fixed numerical factor 16π G N_l.
Load-bearing premise
The entire calculation treats the input one-loop frequency-domain waveform (and its tree-level counterpart) as complete and correct once expanded to 7.5PN order in the center-of-mass frame; any missing or erroneous term in that waveform would appear unchanged in every radiated quantity derived here.
What would settle it
Recompute any low multipole (for example the l=2 or l=0 coefficients) of the radiated energy or of the nonlinear memory from an independent post-Newtonian or multipolar-post-Minkowskian calculation at the same fractional order and check whether the series coefficients agree term by term with the tables given in the paper.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript takes the known one-loop frequency-domain gravitational bremsstrahlung waveform for two non-spinning masses (h ∼ G² + G³) and, working in the center-of-mass frame, extracts the spectral GW radiance dE⁺_gw/(dω dΩ), the angle-integrated energy spectrum dE⁺_gw/dω, and the radiated angular distribution dE_gw/dΩ through O(G⁴). From the multipoles of the angular distribution it obtains the multipole expansion of the nonlinear memory through O(G⁵), at fractional 7.5PN accuracy. Tree-level results in the CM frame are included for completeness. Explicit high-order series for the memory multipoles (l ≤ 5 in the text, l ≤ 17 in ancillaries) and for the energy spectrum (expressed via products of modified Bessel K functions and e^{-u} terms) are given in tables and ancillary files. Standard checks recover the known O(G³) and O(G⁴) total energy and linear-momentum losses and the ν → 0 rest-frame memory of Ref. [31].
Significance. If the results hold, the paper supplies the first CM-frame, 1-loop, 7.5PN multipolar nonlinear memory and the corresponding high-order radiated spectrum and angular distribution for non-spinning gravitational bremsstrahlung. These quantities are directly useful as benchmarks for PN and PM waveform pipelines, for analytic continuation between unbound and bound systems, and for studies of radiation-reaction and high-order tail structure. Strengths include: (i) parameter-free, algebraic extraction from a published waveform; (ii) explicit cross-checks against independent total-loss and rest-frame memory results; (iii) machine-readable ancillary files (spectrum_l_m.m, memory_l_m.m) that make the high-order coefficients usable by others; (iv) a clear extension of the 1-loop waveform PN content from the previous 5PN level to 7.5PN. The work is incremental but high-value post-processing of state-of-the-art PM waveforms.
major comments (2)
- The central claim rests on a new 7.5PN expansion of the one-loop CM-frame waveform (Introduction; cf. prior 5PN result of Ref. [10]). The manuscript does not describe the procedure used to extract this high-order PN series from the closed PM expressions (choice of variables, handling of half-integer Bessel contributions, regularization of soft/hard regions, or validation against intermediate orders). Without at least a short methodological appendix or a clear pointer to a reproducible pipeline, independent verification of the load-bearing input series is difficult, even though the subsequent algebraic steps (radiance → spectrum → angular multipoles → memory) are standard.
- Eq. (3.6), second line: the imaginary 1-loop piece for (l,m)=(3,3) is written as iπ E^{1loop π}_{22} rather than E^{1loop π}_{33}. The same pattern of index slip does not appear in the (3,1) or l=2,4,5 blocks, so this is likely a local typesetting error, but it sits in a defining equation for a multipole that is then tabulated; it should be corrected and the corresponding table entry re-checked against the ancillary file.
minor comments (6)
- Notation: the dimensionless frequency u = ωb/p_∞ is introduced in Sec. II and reused for the spectrum in Sec. IV; a brief reminder that u is not retarded time would help readers skimming only Sec. IV.
- Tables I–X are extremely dense. Consider moving the highest-order coefficients (e.g. p^{11}–p^{14}) fully into the ancillaries and keeping only leading terms plus a statement of the truncation order in the main text, to improve readability.
- In Sec. I, the linear-momentum components P^{rad}_x and P^{rad}_y are given through high orders as checks; it would help to state explicitly which of these coefficients are new versus reproduced from Refs. [15–17].
- Eq. (2.13)–(2.20): the θ′=θ+π, ϕ′=ϕ+π map that relates the two helicity contributions is useful; a one-sentence remark that it preserves ω and is therefore valid for the positive-frequency radiance would make the logic self-contained.
- Reference list: Ref. [11] is cited as arXiv:2604.21522 and Ref. [9] as arXiv:2511.05412; ensure final bibliographic data are updated at proof stage if those works have appeared.
- Abstract and Sec. V: the phrase “fractional 7.5PN accuracy” is clear to specialists but could be glossed once as “O(p_∞^{15}) beyond LO” for broader readability.
Circularity Check
No circularity: direct algebraic extraction of radiance, spectrum, angular multipoles and memory from a previously published one-loop waveform via standard polarization and spherical-harmonic projections.
full rationale
The paper takes as given the one-loop frequency-domain waveform ˆf ∼ G² + G³ (Refs. [6–10]) and the tree-level waveform, expands them to fractional 7.5PN in the CM frame, and applies the textbook relations (1.2)–(1.3) for spectral radiance, (1.5)–(1.6) for the angle-integrated spectrum and angular distribution, and (1.15) for the nonlinear-memory multipoles. These steps are parameter-free algebraic operations (polarization contractions, frequency folding, spherical-harmonic projections, frequency integration). Cross-checks against independent literature results for total Erad and Prad at O(G³) and O(G⁴) and against the ν → 0 rest-frame memory of Ref. [31] confirm consistency but do not feed back into the derivation. Self-citations to the authors’ earlier waveform and spectrum papers supply only the input data and frame conventions; they do not redefine the target observables or force the high-order coefficients by construction. No fitted parameters, uniqueness theorems, or ansatz smuggling appear. The central claims are therefore independent computations, not tautological rearrangements of the inputs.
Axiom & Free-Parameter Ledger
axioms (3)
- domain assumption Einstein’s equations in the weak-field post-Minkowskian expansion govern the classical two-body scattering and the emitted gravitational radiation.
- domain assumption The frequency-domain one-loop waveform h(ω,θ,ϕ)∼G^{2}+G^{3} of Refs. [6–10] is correct and complete when expanded to the required PN order in the CM frame.
- standard math Standard spherical-harmonic and spin-weighted spherical-harmonic decompositions, together with the relation between angular energy distribution and nonlinear memory (Eq. 1.15), hold.
read the original abstract
The frequency-domain gravitational waveform emitted by the scattering of two non-spinning massive particles has recently been derived at next-to-leading, \textit{i.e.} one-loop, post-Minkowskian order, $h(\omega, \theta,\phi) \sim G^2 + G^3$. Building on this one-loop-accurate frequency-domain gravitational waveform, we successively derive the spectral gravitational-wave (GW) radiance, $dE^{\rm gw}/(d\omega d\Omega)$, the radiated GW energy spectrum, $dE^{\rm gw}/d\omega$, and the radiated GW angular distribution, $dE^{\rm gw}/d\Omega$, up to order $G^4$ included. We deduce from the radiated angular distribution the multipole expansion of the non-linear memory up to order $G^5$ included, thereby extending previous results. We work in the center-of-mass frame, and our results reach the fractional 7.5PN accuracy. For completeness, we include the tree-level information (considered in the center-of-mass frame).
Reference graph
Works this paper leans on
-
[1]
linear memory
and the NLO levels (G 4) [16]; at the 2PN fractional accuracy (using the dimensionless angular momentumj in place of the impact parameterb, as in the present case) the corresponding expressions were obtained in Ref. [17], see Appendices G and H there. The beginning of the PN expansion of these expression are given by P rad x = (m 2 −m 1)ν2 GM b 4 πP radG ...
2016
-
[2]
M. Picone,
in the frame of one of the two bodies at orderO(v 30). In the present paper we have chosen to work in the cm frame. Using the simple transformation indicated in Ap- pendix B of Ref. [11] (see also Ref. [32]) it is straightfor- ward to transform the rest-frame energy spectrum into its cm-frame counterpart. Let us indicate here the beginning of the PN expan...
1911
-
[3]
Post-Newtonian Theory for Gravitational Waves,
L. Blanchet, “Post-Newtonian Theory for Gravitational Waves,” Living Rev. Rel.17, 2 (2014) doi:10.12942/lrr- 2014-2 Living Rev.Rel.271, 4 (2024) doi:10.1007/s41114- 024-00050-z [arXiv:1310.1528 [gr-qc]]
-
[4]
Snowmass White Pa- per: Gravitational Waves and Scattering Amplitudes,
A. Buonanno, M. Khalil, D. O’Connell, R. Roiban, M. P. Solon and M. Zeng, “Snowmass White Pa- per: Gravitational Waves and Scattering Amplitudes,” [arXiv:2204.05194 [hep-th]]
-
[5]
N. E. J. Bjerrum-Bohr, P. H. Damgaard, L. Plante and P. Vanhove, “The SAGEX review on scattering ampli- tudes Chapter 13: Post-Minkowskian expansion from scattering amplitudes,” J. Phys. A55, no.44, 443014 (2022) doi:10.1088/1751-8121/ac7a78 [arXiv:2203.13024 [hep-th]]
-
[6]
The SAGEX review on scattering amplitudes Chapter 14: Classical gravity from scattering amplitudes,
D. A. Kosower, R. Monteiro and D. O’Connell, “The SAGEX review on scattering amplitudes Chapter 14: Classical gravity from scattering amplitudes,” J. Phys. A 55, no.44, 443015 (2022) doi:10.1088/1751-8121/ac8846 [arXiv:2203.13025 [hep-th]]
-
[7]
T. Damour, A. Nagar, A. Placidi and P. Rettegno, “Novel Lagrange-multiplier approach to the effective-one- body dynamics of binary systems in post-Minkowskian gravity,” Phys. Rev. D113, no.2, 024042 (2026) doi:10.1103/41sd-g2gb [arXiv:2503.05487 [gr-qc]]
-
[8]
The sub-leading scattering waveform from amplitudes,
A. Herderschee, R. Roiban and F. Teng, “The sub-leading scattering waveform from amplitudes,” JHEP06, 004 (2023) doi:10.1007/JHEP06(2023)004 [arXiv:2303.06112 [hep-th]]. 17 TABLE XI: Energy spectrum at the tree level: list of coefficients fromp 5 ∞ up top 11 ∞ C (5) 00 ν2 32u8 63 + 5576u6 945 − 256u4 945 − 128u2 315 +ν − 64u8 189 − 544u6 63 + 64u4 27 − 14...
-
[9]
In- elastic exponentiation and classical gravitational scat- tering at one loop,
A. Georgoudis, C. Heissenberg and I. Vazquez-Holm, “In- elastic exponentiation and classical gravitational scat- tering at one loop,” JHEP2023, no.06, 126 (2023) doi:10.1007/JHEP06(2023)126 [arXiv:2303.07006 [hep- th]]
-
[10]
One-loop gravi- tational bremsstrahlung and waveforms from a heavy- mass effective field theory,
A. Brandhuber, G. R. Brown, G. Chen, S. De An- gelis, J. Gowdy and G. Travaglini, “One-loop gravi- tational bremsstrahlung and waveforms from a heavy- mass effective field theory,” JHEP06, 048 (2023) doi:10.1007/JHEP06(2023)048 [arXiv:2303.06111 [hep- th]]
-
[11]
Ana- lytic One-loop Scattering Waveform in General Relativ- ity,
B. Giacomo, S. De Angelis and D. A. Kosower, “Ana- lytic One-loop Scattering Waveform in General Relativ- ity,” [arXiv:2511.05412 [hep-th]]
-
[12]
Reconstructing the Gravitational Waveform from Its Probe Limit,
C. Heissenberg and R. Russo, “Reconstructing the Gravitational Waveform from Its Probe Limit,” [arXiv:2511.13835 [hep-th]]
-
[13]
Quadrupolar bremsstrahlung waveform at the third-and-a-half post- Newtonian accuracy,
D. Bini, T. Damour and A. Geralico, “Quadrupolar bremsstrahlung waveform at the third-and-a-half post- Newtonian accuracy,” [arXiv:2604.21522 [gr-qc]]
-
[14]
The mass quadrupole mo- ment of compact binary systems at the fourth post- Newtonian order,
T. Marchand, Q. Henry, F. Larrouturou, S. Marsat, G. Faye and L. Blanchet, “The mass quadrupole mo- ment of compact binary systems at the fourth post- Newtonian order,” Class. Quant. Grav.37, no.21, 215006 (2020) doi:10.1088/1361-6382/ab9ce1 [arXiv:2003.13672 [gr-qc]]
-
[15]
L. Blanchet, G. Faye, Q. Henry, F. Larrouturou and D. Trestini, “Gravitational-Wave Phasing of Quasicircu- 20 TABLE XIV: Energy spectrum at 1-loop: list of coefficients fromp 2 ∞ up top 6 ∞. A(2) 00 64u5 5 + 64u3 15 A(2) 01 192 5 u4 A(2) 11 64u5 5 + 64u3 5 A(2) 0exp 0 A(2) 1exp 0 A(3) 00 ν2 32u9 63 + 4136u7 945 − 1012u5 945 − 4u3 63 +ν − 64u9 189 − 232u7 ...
-
[16]
L. Blanchet, G. Faye, Q. Henry, F. Larrouturou and D. Trestini, “Gravitational-wave flux and quadrupole modes from quasicircular nonspinning compact binaries to the fourth post-Newtonian order,” Phys. Rev. D108, no.6, 064041 (2023) doi:10.1103/PhysRevD.108.064041 [arXiv:2304.11186 [gr-qc]]
-
[17]
Radiative classical gravitational observables atO(G 3) from scattering amplitudes,
E. Herrmann, J. Parra-Martinez, M. S. Ruf and M. Zeng, “Radiative classical gravitational observables atO(G 3) from scattering amplitudes,” JHEP10, 148 (2021) doi:10.1007/JHEP10(2021)148 [arXiv:2104.03957 [hep- th]]
-
[18]
Radiation Reaction and Gravitational Waves at Fourth Post-Minkowskian Order,
C. Dlapa, G. K¨ alin, Z. Liu, J. Neef and R. A. Porto, “Radiation Reaction and Gravitational Waves at Fourth Post-Minkowskian Order,” Phys. Rev. Lett.130, no.10, 101401 (2023) doi:10.1103/PhysRevLett.130.101401 [arXiv:2210.05541 [hep-th]]
-
[19]
Radiative contri- butions to gravitational scattering,
D. Bini, T. Damour and A. Geralico, “Radiative contri- butions to gravitational scattering,” Phys. Rev. D104, no.8, 084031 (2021) doi:10.1103/PhysRevD.104.084031 [arXiv:2107.08896 [gr-qc]]
-
[20]
Blanchet and T
L. Blanchet and T. Damour (1989), draft of [20] incorpo- rated as chapter 6 (pp 194-227) in the 1990 Habilitation thesis of Luc Blanchet; see [19]
1989
-
[21]
Blanchet, “Contribution ` a l’´ etude du rayonnement 21 TABLE XV: Energy spectrum at 1-loop: list of coefficients atp 7 ∞
L. Blanchet, “Contribution ` a l’´ etude du rayonnement 21 TABLE XV: Energy spectrum at 1-loop: list of coefficients atp 7 ∞. A(7) 00 ν4 128u13 57915 + 3488u11 9009 + 37892u9 7371 + 922717u7 135135 − 52597u5 180180 + 439u3 12012 +ν3 − 256u13 57915 − 6056u11 6237 − 4739698u9 405405 − 456674u7 31185 − 140879u5 90090 + 1819u3 8190 +ν2 896u13 289575 + 321064u...
2079
-
[22]
Hereditary effects in grav- itational radiation,
L. Blanchet and T. Damour, “Hereditary effects in grav- itational radiation,” Phys. Rev. D46, 4304-4319 (1992) doi:10.1103/PhysRevD.46.4304
-
[23]
Theory of the detection of short bursts of gravitational radiation,
G. W. Gibbons and S. W. Hawking, “Theory of the detection of short bursts of gravitational radiation,” Phys. Rev. D4(1971), 2191-2197 doi:10.1103/PhysRevD.4.2191
-
[24]
Radiation of grav- itational waves by a cluster of superdense stars,
Y. B. Zel’dovich and A. G. Polnarev, “Radiation of grav- itational waves by a cluster of superdense stars,” Sov. Astron.18(1974), 17
1974
-
[25]
Kinematic Res- onance and Memory Effect in Free Mass Gravitational Antennas,
V. B. Braginsky and L. P. Grishchuk, “Kinematic Res- onance and Memory Effect in Free Mass Gravitational Antennas,” Sov. Phys. JETP62(1985), 427-430
1985
-
[26]
Nonlinear nature of gravitation and gravitational wave experiments,
D. Christodoulou, “Nonlinear nature of gravitation and gravitational wave experiments,” Phys. Rev. Lett.67, 1486-1489 (1991) doi:10.1103/PhysRevLett.67.1486
-
[27]
A. G. Wiseman and C. M. Will, “Christodoulou’s non- 22 TABLE XVII: Energy spectrum at 1-loop: list of coefficients atp 9 ∞. A(9) 00 ν5 − 256u15 3378375 − 970432u13 30405375 − 1574008u11 1216215 − 5888416u9 675675 − 78549157u7 10135125 + 202117u5 1081080 − 10027u3 360360 +ν4 64u15 289575 + 221696u13 2027025 + 24551302u11 6081075 + 30098609u9 1351350 + 2470...
-
[28]
M. Favata, “Post-Newtonian corrections to the gravitational-wave memory for quasi-circular, in- spiralling compact binaries,” Phys. Rev. D80, 024002 (2009) doi:10.1103/PhysRevD.80.024002 [arXiv:0812.0069 [gr-qc]]
-
[29]
Gravitational-wave bursts with memory: The Christodoulou effect,
K. S. Thorne, “Gravitational-wave bursts with memory: The Christodoulou effect,” Phys. Rev. D45, no.2, 520- 524 (1992) doi:10.1103/PhysRevD.45.520
-
[30]
J. Zosso, L. Maga˜ na Zertuche, S. Gasparotto, A. Cogez, H. Inchausp´ e and M. Jacobs, Phys. Rev. D113, no.10, 104033 (2026) doi:10.1103/51xv-zlfy [arXiv:2601.23019 [gr-qc]]
-
[31]
On BMS Invariance of Grav- itational Scattering,
A. Strominger, “On BMS Invariance of Grav- itational Scattering,” JHEP07, 152 (2014) doi:10.1007/JHEP07(2014)152 [arXiv:1312.2229 [hep- th]]
-
[32]
Lectures on the Infrared Structure of Gravity and Gauge Theory,
A. Strominger, “Lectures on the Infrared Structure of Gravity and Gauge Theory,” Princeton University Press, 2018, ISBN 978-0-691-17973-5 [arXiv:1703.05448 [hep- 23 TABLE XVIII: Energy spectrum at 1-loop: list of coefficients atp 10 ∞. A(10) 00 ν4 256u13 57915 + 6976u11 9009 + 75784u9 7371 + 1845434u7 135135 − 52597u5 90090 + 439u3 6006 +ν3 − 512u13 57915...
Pith/arXiv arXiv 2018
-
[33]
Nonlinear Gravitational Mem- ory in the Post-Minkowskian Expansion,
A. Georgoudis, V. Goncalves, C. Heissenberg and J. Parra-Martinez, “Nonlinear Gravitational Mem- ory in the Post-Minkowskian Expansion,” Phys. Rev. Lett.136, no.12, 121401 (2026) doi:10.1103/8m17-s2y8 [arXiv:2506.20733 [hep-th]]
-
[34]
D. Bini, T. Damour and A. Geralico, “Gravita- tional bremsstrahlung waveform at the fourth post- Minkowskian order and the second post-Newtonian level,” Phys. Rev. D110, no.6, 064035 (2024) doi:10.1103/PhysRevD.110.064035 [arXiv:2407.02076 [gr-qc]]
-
[35]
Gravitational waveforms: A tale of two formalisms,
D. Bini, T. Damour, S. De Angelis, A. Geralico, A. Herderschee, R. Roiban and F. Teng, “Gravitational waveforms: A tale of two formalisms,” Phys. Rev. D109, no.12, 125008 (2024) doi:10.1103/PhysRevD.109.125008 [arXiv:2402.06604 [hep-th]]
-
[36]
D. Bini, T. Damour and A. Geralico, “Compar- ing one-loop gravitational bremsstrahlung ampli- tudes to the multipolar-post-Minkowskian wave- form,” Phys. Rev. D108, no.12, 124052 (2023) doi:10.1103/PhysRevD.108.124052 [arXiv:2309.14925 [gr-qc]]
-
[37]
Local in Time Conservative Binary Dynamics at Fourth Post-Minkowskian Order,
C. Dlapa, G. K¨ alin, Z. Liu and R. A. Porto, “Local in Time Conservative Binary Dynamics at Fourth Post-Minkowskian Order,” Phys. Rev. Lett.132, no.22, 221401 (2024) doi:10.1103/PhysRevLett.132.221401 [arXiv:2403.04853 [hep-th]]
-
[38]
Fourth post-Minkowskian local-in-time conservative dynamics of binary sys- tems,
D. Bini and T. Damour, “Fourth post-Minkowskian local-in-time conservative dynamics of binary sys- tems,” Phys. Rev. D110, no.6, 064005 (2024) doi:10.1103/PhysRevD.110.064005 [arXiv:2406.04878 [gr-qc]]
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.