pith. sign in

arxiv: 2606.19757 · v1 · pith:WPTER5MAnew · submitted 2026-06-18 · 🌀 gr-qc · astro-ph.CO· hep-ph

Graviton Floor

Himeka Matsuo , Asuka Ito , Kazunori Kohri , Teruaki Suyama , Ryutaro Tomomatsu This is my paper

Pith reviewed 2026-06-26 17:04 UTC · model grok-4.3

classification 🌀 gr-qc astro-ph.COhep-ph
keywords graviton backgroundblazar jetsphoton conversionmagnetic fieldshigh-frequency gravitational wavesneutrino floorcosmic photon backgroundgravitational wave detectors
0
0 comments X

The pith

The cosmic photon background converts into a graviton background primarily in blazar jets, establishing a floor for high-frequency gravitational wave detectors.

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

This paper examines how photons from the cosmic background turn into gravitons when passing through magnetic fields in the Milky Way and blazar jets. The authors determine that blazar jets provide the dominant contribution to the resulting graviton background. This background acts as a fundamental limit, or floor, for detectors looking for high-frequency gravitational waves from new physics, similar to how the neutrino floor limits dark matter searches. Understanding this floor is essential because it sets the sensitivity threshold that future experiments must overcome or account for when probing beyond-standard-model physics.

Core claim

The paper finds that the graviton background produced by photon conversion in the presence of background magnetic fields is dominated by the contribution from blazar jets. This graviton background constitutes a graviton floor for high-frequency gravitational wave detectors searching for new physics, analogous to the neutrino floor.

What carries the argument

Photon-to-graviton conversion in background magnetic fields within blazar jets, which generates the dominant graviton background.

Load-bearing premise

The strength and coherence of magnetic fields in blazar jets, along with the spectrum of the photon background, are as modeled; weaker or less ordered fields would reduce the graviton production below detectable levels.

What would settle it

A measurement showing the high-frequency gravitational wave background significantly below the predicted level from blazar jet conversions, or direct observations indicating much weaker magnetic fields in blazars than assumed.

Figures

Figures reproduced from arXiv: 2606.19757 by Asuka Ito, Himeka Matsuo, Kazunori Kohri, Ryutaro Tomomatsu, Teruaki Suyama.

Figure 1
Figure 1. Figure 1: FIG. 1. Stochastic gravitational waves produced in the Milky Way Galaxy from the cosmic photon [PITH_FULL_IMAGE:figures/full_fig_p007_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Schematic illustration of the accumulated gravitational waves produced in individual blazar [PITH_FULL_IMAGE:figures/full_fig_p008_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. The black line shows stochastic gravitational waves from graviton conversion in blazar [PITH_FULL_IMAGE:figures/full_fig_p011_3.png] view at source ↗
read the original abstract

It has been observed that the Universe is permeated by the cosmic photon background, ranging from radio waves to gamma rays. We investigate the conversion of the photon background into gravitons in the presence of background magnetic fields in the Milky Way Galaxy and in blazar jets. We find that the resulting graviton background is dominated by the contribution generated in blazar jets. Importantly, this graviton background constitutes a graviton floor for high-frequency gravitational wave detectors searching for new physics, analogous to the neutrino floor.

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 / 0 minor

Summary. The manuscript investigates photon-to-graviton conversion of the cosmic photon background in the presence of magnetic fields in the Milky Way and blazar jets. It concludes that the resulting graviton background is dominated by the blazar-jet contribution and that this background sets a fundamental 'graviton floor' for high-frequency gravitational-wave detectors, analogous to the neutrino floor.

Significance. If the central calculation is robust, the result would be significant for high-frequency GW detector design and data interpretation, establishing an astrophysical background limit that must be accounted for when searching for new physics. The neutrino-floor analogy is conceptually useful provided the dominance claim survives variation of the input parameters.

major comments (2)
  1. [Abstract] Abstract: the claim of blazar-jet dominance (and therefore the existence of a detectable graviton floor) rests on the adopted magnetic-field amplitudes, coherence lengths, and photon spectrum in the rate integral. The manuscript must show that the blazar term remains dominant when these quantities are varied within observationally allowed ranges; if weaker or more turbulent fields are used, the floor may fall below both Galactic contributions and detector thresholds.
  2. [Calculation section (implied by abstract)] The conversion probability scales with (B_perp * L_coh)^2; without explicit equations, integration limits, or error estimates for the blazar term, it is impossible to assess whether the reported dominance is a genuine prediction or an artifact of the chosen fiducial values.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful review and constructive comments. We address the major points below and will revise the manuscript to improve transparency and robustness.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the claim of blazar-jet dominance (and therefore the existence of a detectable graviton floor) rests on the adopted magnetic-field amplitudes, coherence lengths, and photon spectrum in the rate integral. The manuscript must show that the blazar term remains dominant when these quantities are varied within observationally allowed ranges; if weaker or more turbulent fields are used, the floor may fall below both Galactic contributions and detector thresholds.

    Authors: We agree that the dominance claim requires explicit verification against parameter variations. In the revised manuscript we will add a parameter-variation study (or appendix) scanning magnetic-field amplitudes, coherence lengths, and photon spectra over observationally allowed ranges, demonstrating whether blazar-jet dominance persists or identifying the boundary conditions under which it holds. revision: yes

  2. Referee: [Calculation section (implied by abstract)] The conversion probability scales with (B_perp * L_coh)^2; without explicit equations, integration limits, or error estimates for the blazar term, it is impossible to assess whether the reported dominance is a genuine prediction or an artifact of the chosen fiducial values.

    Authors: We acknowledge the need for greater calculational transparency. The revised version will include the explicit conversion-probability formula (showing the (B_perp L_coh)^2 scaling), the precise integration limits applied to the blazar-jet contribution, and quantitative error estimates or uncertainty ranges for the resulting graviton background. revision: yes

Circularity Check

0 steps flagged

No circularity: result follows from explicit integration over external inputs

full rationale

The abstract states that graviton production is computed from photon conversion in Galactic and blazar magnetic fields, with the blazar term dominating the integrated flux. No equation, parameter fit, or self-citation is shown that would make the final graviton spectrum equivalent to its inputs by construction. The dominance statement is a direct numerical outcome of the adopted B-field amplitudes, coherence lengths, and photon number densities; altering those inputs changes the result, so the derivation remains independent of the target claim.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only; no explicit free parameters, axioms, or invented entities are stated. The claim implicitly depends on standard assumptions about photon-graviton mixing in magnetic fields and the adopted astrophysical inputs for B-fields and photon spectra.

pith-pipeline@v0.9.1-grok · 5615 in / 1055 out tokens · 25367 ms · 2026-06-26T17:04:39.473424+00:00 · methodology

discussion (0)

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

Reference graph

Works this paper leans on

70 extracted references · 1 canonical work pages · 1 internal anchor

  1. [1]

    L. M. Widrow, Rev. Mod. Phys.74, 775 (2002), arXiv:astro-ph/0207240

    Pith/arXiv arXiv 2002

  2. [2]

    M. E. Gertsenshtein, Sov. Phys. JETP14, 84 (1962). 12

    1962

  3. [3]

    Raffelt and L

    G. Raffelt and L. Stodolsky, Phys. Rev. D37, 1237 (1988)

    1988

  4. [4]

    M. S. Pshirkov and D. Baskaran, Phys. Rev. D80, 042002 (2009), arXiv:0903.4160 [gr-qc]

    Pith/arXiv arXiv 2009

  5. [5]

    A. D. Dolgov and D. Ejlli, JCAP12, 003 (2012), arXiv:1211.0500 [gr-qc]

    Pith/arXiv arXiv 2012

  6. [6]

    Domcke and C

    V. Domcke and C. Garcia-Cely, Phys. Rev. Lett.126, 021104 (2021), arXiv:2006.01161 [astro- ph.CO]

    arXiv 2021

  7. [7]

    Ramazanov, R

    S. Ramazanov, R. Samanta, G. Trenkler, and F. R. Urban, JCAP06, 019 (2023), arXiv:2304.11222 [astro-ph.HE]

    arXiv 2023

  8. [8]

    T. Liu, J. Ren, and C. Zhang, Phys. Rev. Lett.132, 131402 (2024), arXiv:2305.01832 [hep-ph]

    arXiv 2024

  9. [9]

    A. Ito, K. Kohri, and K. Nakayama, Phys. Rev. D109, 063026 (2024), arXiv:2305.13984 [gr-qc]

    arXiv 2024

  10. [10]

    A. Ito, K. Kohri, and K. Nakayama, PTEP2024, 023E03 (2024), arXiv:2309.14765 [gr-qc]

    arXiv 2024

  11. [11]

    Dandoy, T

    V. Dandoy, T. Bert´ olez-Mart´ ınez, and F. Costa, JCAP12, 023 (2024), arXiv:2402.14092 [gr-qc]

    arXiv 2024

  12. [12]

    Y. He, S. K. Giri, R. Sharma, S. Mtchedlidze, and I. Georgiev, JCAP05, 051 (2024), arXiv:2312.17636 [astro-ph.CO]

    arXiv 2024

  13. [13]

    Lella, F

    A. Lella, F. Calore, P. Carenza, and A. Mirizzi, Phys. Rev. D110, 083042 (2024), arXiv:2406.17853 [hep-ph]

    arXiv 2024

  14. [14]

    J. I. McDonald and S. A. R. Ellis, Phys. Rev. D110, 103003 (2024), arXiv:2406.18634 [hep- ph]

    arXiv 2024

  15. [15]

    Kushwaha and R

    A. Kushwaha and R. K. Jain, Phys. Rev. D112, L021301 (2025), arXiv:2502.12517 [astro- ph.CO]

    arXiv 2025

  16. [16]

    J.-K. Li, W. Hong, and T.-J. Zhang, Astrophys. J.985, 137 (2025), arXiv:2504.13115 [astro- ph.CO]

    arXiv 2025

  17. [17]

    Amaralet al., (2026), arXiv:2603.24645 [astro-ph.IM]

    D. Amaralet al., (2026), arXiv:2603.24645 [astro-ph.IM]

    arXiv 2026

  18. [18]

    Baker and H

    E. Baker and H. Liu, (2026), arXiv:2606.09968 [hep-ph]

    Pith/arXiv arXiv 2026

  19. [19]

    Matsuo and A

    H. Matsuo and A. Ito, JCAP10, 061 (2025), arXiv:2505.08457 [gr-qc]

    arXiv 2025

  20. [20]

    R. Hill, K. W. Masui, and D. Scott, Appl. Spectrosc.72, 663 (2018), arXiv:1802.03694 [astro- ph.CO]

    Pith/arXiv arXiv 2018

  21. [21]

    Chen, Phys

    P. Chen, Phys. Rev. Lett.74, 634 (1995), [Erratum: Phys.Rev.Lett. 74, 3091 (1995)]

    1995

  22. [22]

    A. N. Cillis and D. D. Harari, Phys. Rev. D54, 4757 (1996), arXiv:astro-ph/9609200

    Pith/arXiv arXiv 1996

  23. [23]

    Chen and T

    P. Chen and T. Suyama, Phys. Rev. D88, 123521 (2013), arXiv:1309.0537 [astro-ph.CO]. 13

    Pith/arXiv arXiv 2013

  24. [24]

    Fujita, K

    T. Fujita, K. Kamada, and Y. Nakai, Phys. Rev. D102, 103501 (2020), arXiv:2002.07548 [astro-ph.CO]

    arXiv 2020

  25. [25]

    Magnetic Fields in the Milky Way

    M. Haverkorn, (2014), 10.1007/978-3-662-44625-6 17, arXiv:1406.0283 [astro-ph.GA]

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1007/978-3-662-44625-6 2014

  26. [26]

    Boulangeret al., JCAP08, 049 (2018), arXiv:1805.02496 [astro-ph.GA]

    F. Boulangeret al., JCAP08, 049 (2018), arXiv:1805.02496 [astro-ph.GA]

    Pith/arXiv arXiv 2018

  27. [27]

    Haverkorn, B

    M. Haverkorn, B. M. Gaensler, N. M. McClure-Griffiths, J. M. Dickey, and A. J. Green, Astrophys. J.609, 776 (2004), arXiv:astro-ph/0403655

    Pith/arXiv arXiv 2004

  28. [28]

    Iacobelliet al., Astron

    M. Iacobelliet al., Astron. Astrophys.558, A72 (2013), arXiv:1308.2804 [astro-ph.GA]

    Pith/arXiv arXiv 2013

  29. [29]

    Haverkorn, J

    M. Haverkorn, J. C. Brown, B. M. Gaensler, and N. M. McClure-Griffiths, Astrophys. J.680, 362 (2008), arXiv:0802.2740 [astro-ph]

    Pith/arXiv arXiv 2008

  30. [30]

    J. Fan, H. Xiao, W. Yang, L. Zhang, A. A. Strigachev, R. S. Bachev, and J. Yang, The Astrophysical Journal Supplement Series268, 23 (2023)

    2023

  31. [31]

    Aggarwalet al., Living Rev

    N. Aggarwalet al., Living Rev. Rel.28, 10 (2025), arXiv:2501.11723 [gr-qc]

    arXiv 2025

  32. [32]

    A. Ito, T. Ikeda, K. Miuchi, and J. Soda, Eur. Phys. J. C80, 179 (2020), arXiv:1903.04843 [gr-qc]

    arXiv 2020

  33. [33]

    Ito and J

    A. Ito and J. Soda, Eur. Phys. J. C80, 545 (2020), arXiv:2004.04646 [gr-qc]

    arXiv 2020

  34. [34]

    Berlin, D

    A. Berlin, D. Blas, R. Tito D’Agnolo, S. A. R. Ellis, R. Harnik, Y. Kahn, and J. Sch¨ utte-Engel, Phys. Rev. D105, 116011 (2022), arXiv:2112.11465 [hep-ph]

    arXiv 2022

  35. [35]

    Ito and J

    A. Ito and J. Soda, Eur. Phys. J. C83, 766 (2023), arXiv:2212.04094 [gr-qc]

    arXiv 2023

  36. [36]

    Ito and R

    A. Ito and R. Kitano, JCAP04, 068 (2024), arXiv:2309.02992 [gr-qc]

    arXiv 2024

  37. [37]

    Berlin, D

    A. Berlin, D. Blas, R. Tito D’Agnolo, S. A. R. Ellis, R. Harnik, Y. Kahn, J. Sch¨ utte-Engel, and M. Wentzel, Phys. Rev. D108, 084058 (2023), arXiv:2303.01518 [hep-ph]

    arXiv 2023

  38. [38]

    Bringmann, V

    T. Bringmann, V. Domcke, E. Fuchs, and J. Kopp, Phys. Rev. D108, L061303 (2023), arXiv:2304.10579 [hep-ph]

    arXiv 2023

  39. [39]

    Kanno, J

    S. Kanno, J. Soda, and A. Taniguchi, Eur. Phys. J. C85, 31 (2025), arXiv:2311.03890 [gr-qc]

    arXiv 2025

  40. [40]

    A. Ito, R. Kitano, W. Nakano, and R. Takai, JCAP05, 039 (2026), arXiv:2512.19053 [gr-qc]

    Pith/arXiv arXiv 2026

  41. [41]

    Billard, L

    J. Billard, L. Strigari, and E. Figueroa-Feliciano, Phys. Rev. D89, 023524 (2014), arXiv:1307.5458 [hep-ph]

    Pith/arXiv arXiv 2014

  42. [42]

    C. A. J. O’Hare, Phys. Rev. Lett.127, 251802 (2021), arXiv:2109.03116 [hep-ph]

    arXiv 2021

  43. [43]

    Kartavtsev, G

    A. Kartavtsev, G. Raffelt, and H. Vogel, JCAP01, 024 (2017), arXiv:1611.04526 [astro- ph.HE]

    Pith/arXiv arXiv 2017

  44. [44]

    J. M. Cordes and T. J. W. Lazio, (2002), arXiv:astro-ph/0207156. 14

    Pith/arXiv arXiv 2002

  45. [45]

    A. P. Marscher and S. G. Jorstad, Galaxies9, 27 (2021), arXiv:2105.00094 [astro-ph.HE]

    arXiv 2021

  46. [46]

    Tavecchio, L

    F. Tavecchio, L. Maraschi, and G. Ghisellini, Astrophys. J.509, 608 (1998), arXiv:astro- ph/9809051

    arXiv 1998

  47. [47]

    V. S. Paliya, L. Marcotulli, M. Ajello, M. Joshi, S. Sahayanathan, A. R. Rao, and D. Hart- mann, Astrophys. J.851, 33 (2017), arXiv:1711.01292 [astro-ph.HE]

    Pith/arXiv arXiv 2017

  48. [48]

    Cerruti, Galaxies8, 72 (2020), arXiv:2012.13302 [astro-ph.HE]

    M. Cerruti, Galaxies8, 72 (2020), arXiv:2012.13302 [astro-ph.HE]

    arXiv 2020

  49. [49]

    Nasa/ipac extragalactic database,

    C. I. of Technology, “Nasa/ipac extragalactic database,”

  50. [50]

    Ringwald, J

    A. Ringwald, J. Sch¨ utte-Engel, and C. Tamarit, JCAP03, 054 (2021), arXiv:2011.04731 [hep-ph]

    arXiv 2021

  51. [51]

    Y. S. Furuta, M. Karˇ ciauskas, K. Kohri, and A. S´ aez, (2025), arXiv:2511.23182 [astro-ph.CO]

    arXiv 2025

  52. [52]

    Jiang and T

    Y. Jiang and T. Suyama, JCAP02, 041 (2025), arXiv:2410.11175 [astro-ph.CO]

    arXiv 2025

  53. [53]

    Garc´ ıa-Cely and A

    C. Garc´ ıa-Cely and A. Ringwald, Phys. Rev. Lett.135, 061001 (2025), arXiv:2407.18297 [hep-ph]

    arXiv 2025

  54. [54]

    B. J. Carr, K. Kohri, Y. Sendouda, and J. Yokoyama, Phys. Rev. D81, 104019 (2010), arXiv:0912.5297 [astro-ph.CO]

    Pith/arXiv arXiv 2010

  55. [55]

    Sasaki, T

    M. Sasaki, T. Suyama, T. Tanaka, and S. Yokoyama, Class. Quant. Grav.35, 063001 (2018), arXiv:1801.05235 [astro-ph.CO]

    Pith/arXiv arXiv 2018

  56. [56]

    B. Carr, K. Kohri, Y. Sendouda, and J. Yokoyama, Rept. Prog. Phys.84, 116902 (2021), arXiv:2002.12778 [astro-ph.CO]

    Pith/arXiv arXiv 2021

  57. [57]

    Wang, Y.-F

    S. Wang, Y.-F. Wang, Q.-G. Huang, and T. G. F. Li, Phys. Rev. Lett.120, 191102 (2018), arXiv:1610.08725 [astro-ph.CO]

    Pith/arXiv arXiv 2018

  58. [58]

    S. Wang, T. Terada, and K. Kohri, Phys. Rev. D99, 103531 (2019), [Erratum: Phys.Rev.D 101, 069901 (2020)], arXiv:1903.05924 [astro-ph.CO]

    arXiv 2019

  59. [59]

    Franciolini, A

    G. Franciolini, A. Maharana, and F. Muia, Phys. Rev. D106, 103520 (2022), arXiv:2205.02153 [astro-ph.CO]

    arXiv 2022

  60. [60]

    Kohri, T

    K. Kohri, T. Terada, and T. T. Yanagida, Phys. Rev. D111, 063543 (2025), arXiv:2409.06365 [astro-ph.CO]

    arXiv 2025

  61. [61]

    Dvali, L

    G. Dvali, L. Eisemann, M. Michel, and S. Zell, Phys. Rev. D102, 103523 (2020), arXiv:2006.00011 [hep-th]

    arXiv 2020

  62. [62]

    Thoss, A

    V. Thoss, A. Burkert, and K. Kohri, Mon. Not. Roy. Astron. Soc.532, 451 (2024), arXiv:2402.17823 [astro-ph.CO]. 15

    arXiv 2024

  63. [63]

    Chaudhuri, K

    A. Chaudhuri, K. Kohri, and V. Thoss, JCAP11, 057 (2025), arXiv:2506.20717 [astro-ph.CO]

    arXiv 2025

  64. [64]

    Y. Ema, R. Jinno, and K. Nakayama, JCAP09, 015 (2020), arXiv:2006.09972 [astro-ph.CO]

    arXiv 2020

  65. [65]

    J. M. Cline and Y. Xu, (2026), arXiv:2605.16201 [hep-ph]

    Pith/arXiv arXiv 2026

  66. [66]

    V. A. Acciariet al.(MAGIC), Astron. Astrophys.670, A145 (2023), arXiv:2210.03321 [astro- ph.HE]

    arXiv 2023

  67. [67]

    Jedamzik and A

    K. Jedamzik and A. Saveliev, Phys. Rev. Lett.123, 021301 (2019), arXiv:1804.06115 [astro- ph.CO]

    Pith/arXiv arXiv 2019

  68. [68]

    P. A. R. Adeet al.(Planck), Astron. Astrophys.594, A19 (2016), arXiv:1502.01594 [astro- ph.CO]

    Pith/arXiv arXiv 2016

  69. [69]

    Paoletti, J

    D. Paoletti, J. Chluba, F. Finelli, and J. A. Rubi˜ no-Martin, Mon. Not. Roy. Astron. Soc. 517, 3916 (2022), arXiv:2204.06302 [astro-ph.CO]

    arXiv 2022

  70. [70]

    M. S. Pshirkov, P. G. Tinyakov, and F. R. Urban, Phys. Rev. Lett.116, 191302 (2016), arXiv:1504.06546 [astro-ph.CO]. 16

    Pith/arXiv arXiv 2016