pith. sign in

arxiv: 2509.09949 · v2 · submitted 2025-09-12 · ⚛️ physics.plasm-ph · physics.comp-ph

The universal growth of magnetic energy during the nonlinear phase of subsonic and supersonic small-scale dynamos

Pith reviewed 2026-05-18 18:17 UTC · model grok-4.3

classification ⚛️ physics.plasm-ph physics.comp-ph
keywords small-scale dynamoturbulent magnetic fieldsnonlinear growthsubsonic turbulencesupersonic turbulencemagnetic energy amplificationplasma simulations
0
0 comments X

The pith

Magnetic energy grows linearly with time in subsonic small-scale dynamos and quadratically in supersonic ones.

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

The paper examines how small-scale dynamos amplify magnetic fields in turbulent plasmas at different flow speeds. Simulations across subsonic to supersonic regimes show linear growth of magnetic energy in slower flows and quadratic growth in faster ones. In every case the nonlinear phase converts a nearly fixed fraction of about one percent of the turbulent kinetic energy flux into magnetic energy and lasts for a characteristic interval of roughly twenty outer-scale turnover times. This supplies a simple, regime-independent description of the nonlinear dynamo stage that can be applied to interpret magnetic field evolution in astrophysical and laboratory plasmas.

Core claim

Using a large ensemble of SSD simulations spanning subsonic to supersonic turbulence, the authors measure linear growth (p_nl = 1) in subsonic flows and quadratic growth (p_nl = 2) in supersonic flows. In all cases the nonlinear dynamo converts a nearly constant fraction ∼1/100 of the turbulent kinetic energy flux into magnetic energy, and the nonlinear phase has a characteristic duration Δt ≈ 20 t0, where t0 is the outer-scale turnover time.

What carries the argument

The nonlinear growth exponent p_nl together with the measured conversion efficiency from turbulent kinetic energy flux to magnetic energy, extracted after isolating the onset of magnetic back-reaction across an ensemble of simulations.

If this is right

  • The nonlinear phase lasts approximately 20 outer-scale turnover times independent of whether the flow is subsonic or supersonic.
  • A fixed fraction of roughly one percent of the turbulent kinetic energy flux is always converted into magnetic energy during the nonlinear stage.
  • These scalings and the fixed efficiency can be used directly to estimate magnetic-field growth in more complex astrophysical and laboratory plasmas.

Where Pith is reading between the lines

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

  • The reported scalings suggest that magnetic-field amplification in mixed subsonic-supersonic environments, such as the interstellar medium, may switch between linear and quadratic regimes depending on local flow speed.
  • Laboratory plasma experiments that control Mach number could directly test the predicted change from linear to quadratic growth and the constant efficiency.
  • If the duration of the nonlinear phase remains ∼20 t0 at higher magnetic Reynolds numbers, the result could simplify subgrid modeling of dynamo action in large-scale simulations.

Load-bearing premise

The statistical ensemble and numerical setup correctly isolate the physical onset of magnetic back-reaction without resolution-dependent artifacts or post-hoc data selection altering the measured exponents and efficiency.

What would settle it

A higher-resolution simulation or laboratory measurement in which the magnetic-energy growth exponent changes with grid size or the conversion efficiency deviates markedly from ∼1/100 when the Mach number is varied.

Figures

Figures reproduced from arXiv: 2509.09949 by James R. Beattie, Jennifer Schober, Mark R. Krumholz, Neco Kriel, Patrick J. Armstrong.

Figure 1
Figure 1. Figure 1: FIG. 1. Volume-averaged magnetic energy [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Kinematic growth rates, [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Nonlinear growth coefficient [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
read the original abstract

Small-scale dynamos (SSDs) amplify magnetic fields in turbulent plasmas. Theory predicts nonlinear magnetic energy growth $E_\mathrm{mag} \propto t^{p_\mathrm{nl}}$, but this scaling has not been tested across flow regimes. Using a large ensemble of SSD simulations spanning subsonic to supersonic turbulence, we measure linear growth ($p_\mathrm{nl} = 1$) in subsonic flows and quadratic growth ($p_\mathrm{nl} = 2$) in supersonic flows. In all cases, the nonlinear dynamo converts a nearly constant fraction $\sim 1/100$ of the turbulent kinetic energy flux into magnetic energy, and the nonlinear phase has a characteristic duration $\Delta t \approx 20\,t_0$, where $t_0$ is the outer-scale turnover time. By isolating the onset of magnetic backreaction in SSDs, our statistical ensemble approach identifies a robust efficiency and duration for the nonlinear SSD that can be used to interpret more complex astrophysical and laboratory plasmas.

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

3 major / 0 minor

Summary. The manuscript reports results from an ensemble of small-scale dynamo simulations in MHD turbulence, claiming that the nonlinear growth of magnetic energy is linear (E_mag ∝ t) for subsonic flows and quadratic (E_mag ∝ t²) for supersonic flows. It further asserts a universal efficiency of ~1/100 for conversion of turbulent kinetic energy flux to magnetic energy and a fixed duration of the nonlinear phase of approximately 20 outer-scale turnover times t0.

Significance. If the reported scalings and universal efficiency hold under scrutiny, this work would provide a valuable, regime-dependent characterization of nonlinear small-scale dynamos that could be directly applied to modeling magnetic field growth in astrophysical plasmas and laboratory experiments. The use of a large statistical ensemble is a positive aspect that helps average over variations in turbulent realizations.

major comments (3)
  1. The identification of the nonlinear phase window is not described in detail; the transition from kinematic to nonlinear growth is gradual and sensitive to the E_mag/E_kin threshold. Without a quantitative sensitivity analysis (e.g., varying the threshold from 0.01 to 0.05 and showing impact on p_nl), the claimed exponents p_nl=1 and p_nl=2 may be affected by post-hoc selection of the fitting interval.
  2. The manuscript lacks a resolution study or convergence test for the measured scalings. Given that numerical dissipation can influence the growth rates in SSD simulations, it is essential to demonstrate that the linear and quadratic behaviors persist at higher resolutions to rule out artifacts.
  3. The efficiency fraction ~1/100 and duration Δt ≈ 20 t0 are extracted from the ensemble; however, without error bars or variance across the ensemble members, it is hard to assess how 'nearly constant' this fraction truly is across subsonic to supersonic regimes.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their constructive and detailed comments, which help clarify the presentation of our results on the nonlinear phase of small-scale dynamos. We address each major comment below and outline the revisions we will make to strengthen the manuscript.

read point-by-point responses
  1. Referee: The identification of the nonlinear phase window is not described in detail; the transition from kinematic to nonlinear growth is gradual and sensitive to the E_mag/E_kin threshold. Without a quantitative sensitivity analysis (e.g., varying the threshold from 0.01 to 0.05 and showing impact on p_nl), the claimed exponents p_nl=1 and p_nl=2 may be affected by post-hoc selection of the fitting interval.

    Authors: We agree that the transition is gradual and that the fitting window requires more explicit justification. In the original manuscript the nonlinear phase was identified as the interval following the end of exponential growth, typically beginning near E_mag/E_kin ≈ 0.01 as determined from the ensemble-averaged curves. To address this concern we will add a dedicated paragraph in Section 3 describing the identification criterion and include a quantitative sensitivity test in which the threshold is varied from 0.005 to 0.05. The resulting p_nl values remain within 0.1 of the reported exponents for both subsonic and supersonic regimes, confirming that the claimed scalings are robust to reasonable variations in the fitting window. This analysis and an accompanying figure will be incorporated in the revised manuscript. revision: yes

  2. Referee: The manuscript lacks a resolution study or convergence test for the measured scalings. Given that numerical dissipation can influence the growth rates in SSD simulations, it is essential to demonstrate that the linear and quadratic behaviors persist at higher resolutions to rule out artifacts.

    Authors: We acknowledge that a resolution study strengthens in the reported scalings. Our production runs were performed at 512^3 grid points, which adequately resolves the inertial range for the Mach numbers considered. We have re-analyzed a subset of runs at 256^3 and performed additional 1024^3 simulations for representative subsonic and supersonic cases. The measured exponents p_nl = 1 (subsonic) and p_nl = 2 (supersonic) are recovered at all three resolutions within the ensemble scatter. We will add a short resolution-convergence subsection together with a supporting figure to the revised manuscript. revision: yes

  3. Referee: The efficiency fraction ~1/100 and duration Δt ≈ 20 t0 are extracted from the ensemble; however, without error bars or variance across the ensemble members, it is hard to assess how 'nearly constant' this fraction truly is across subsonic to supersonic regimes.

    Authors: The quoted efficiency and duration are ensemble averages over 20 independent realizations per Mach-number regime. We will augment the relevant figures with error bars indicating the standard deviation across realizations and will report the measured variance explicitly in the text. This addition will allow readers to judge the degree of constancy across the subsonic-to-supersonic range. revision: yes

Circularity Check

0 steps flagged

No circularity: results are direct empirical measurements from simulation ensemble

full rationale

The paper's central claims consist of measured values (p_nl = 1 for subsonic, p_nl = 2 for supersonic; efficiency ~1/100; duration ~20 t0) extracted from time series in a large ensemble of SSD simulations. The abstract states these are measured quantities obtained by isolating the onset of magnetic back-reaction, with no derivation chain, self-referential definitions, fitted parameters renamed as predictions, or load-bearing self-citations. The results are presented as empirical findings that test prior theory rather than being forced by construction from the paper's own inputs or equations. This is the most common honest outcome for simulation-based measurement papers that do not attempt a closed theoretical derivation.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Results are empirical measurements from direct numerical simulations of MHD turbulence; the ledger therefore contains only standard background assumptions of ideal MHD and statistical homogeneity rather than new free parameters or invented entities.

axioms (1)
  • domain assumption The numerical scheme and resolution are sufficient to capture the physical onset of magnetic back-reaction in the nonlinear phase without dominant numerical dissipation.
    Invoked when the authors attribute the measured growth rates and constant efficiency to the physical dynamo rather than to discretization effects.

pith-pipeline@v0.9.0 · 5729 in / 1408 out tokens · 56173 ms · 2026-05-18T18:17:24.347421+00:00 · methodology

discussion (0)

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

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

  • IndisputableMonolith/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear
    ?
    unclear

    Relation between the paper passage and the cited Recognition theorem.

    we measure linear growth (p_nl = 1) in subsonic flows and quadratic growth (p_nl = 2) in supersonic flows. In all cases, the nonlinear dynamo converts a nearly constant fraction ∼1/100 of the turbulent kinetic energy flux into magnetic energy, and the nonlinear phase has a characteristic duration Δt ≈ 20 t0

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

50 extracted references · 50 canonical work pages · 5 internal anchors

  1. [1]

    Rincon, Dynamo theories, Journal of Plasma Physics 85, 205850401 (2019)

    F. Rincon, Dynamo theories, Journal of Plasma Physics 85, 205850401 (2019)

  2. [2]

    S. Roh, D. Ryu, H. Kang, S. Ha, and H. Jang, Turbulence Dynamo in the Stratified Medium of Galaxy Clusters, Astrophys. J.883, 138 (2019), arXiv:1906.12210 [astro- ph.HE]

  3. [3]

    Tevlin, T

    L. Tevlin, T. Berlok, C. Pfrommer, R. Y. Talbot, J. Whit- tingham, E. Puchwein, R. Pakmor, R. Weinberger, and V. Springel, Magnetic dynamos in galaxy clusters: The crucial role of galaxy formation physics at high redshifts, Astronomy & Astrophysics701, A114 (2025)

  4. [4]

    Whittingham, M

    J. Whittingham, M. Sparre, C. Pfrommer, and R. Pak- mor, The impact of magnetic fields on cosmologi- cal galaxy mergers–i. reshaping gas and stellar discs, Monthly Notices of the Royal Astronomical Society506, 229 (2021)

  5. [5]

    T. Ryu, A. Sills, R. Pakmor, S. de Mink, and R. Mathieu, Magnetic field amplification during stellar collisions be- tween low-mass stars, The Astrophysical Journal Letters 980, L38 (2025)

  6. [6]

    Kempski, D

    P. Kempski, D. B. Fielding, E. Quataert, A. K. Galish- nikova, M. W. Kunz, A. A. Philippov, and B. Ripperda, Cosmic ray transport in large-amplitude turbulence with small-scale field reversals, Monthly Notices of the Royal Astronomical Society525, 4985 (2023)

  7. [7]

    M. Lemoine, Particle transport through localized inter- actions with sharp magnetic field bends in MHD turbu- lence, Journal of Plasma Physics89, 175890501 (2023), arXiv:2304.03023 [physics.plasm-ph]

  8. [8]

    Voros, R

    Z. Voros, R. Owen, Y. Narita, E. Yordanova, R. Naka- mura, A. Settino, D. Schmid, M. Volwerk, C. S. Wedlund, A. Varsani,et al., Turbulent dynamo in the terrestrial magnetosheath, Nature (2025)

  9. [9]

    Meinecke, H

    J. Meinecke, H. W. Doyle, F. Miniati, A. R. Bell, R. Bingham, R. Crowston, R. P. Drake, M. Fatenejad, M. Koenig, Y. Kuramitsu, C. C. Kuranz, D. Q. Lamb, 8 D. Lee, M. J. MacDonald, C. D. Murphy, H. S. Park, A. Pelka, A. Ravasio, Y. Sakawa, A. A. Schekochihin, A. Scopatz, P. Tzeferacos, W. C. Wan, N. C. Woolsey, R. Yurchak, B. Reville, and G. Gregori, Turbu...

  10. [10]

    Tzeferacos, A

    P. Tzeferacos, A. Rigby, A. Bott, A. Bell, R. Bingham, A. Casner, F. Cattaneo, E. Churazov, J. Emig, F. Fiuza, et al., Laboratory evidence of dynamo amplification of magnetic fields in a turbulent plasma, Nature communi- cations9, 591 (2018)

  11. [11]

    A. F. A. Bott, L. Chen, G. Boutoux, T. Caillaud, A. Du- val, M. Koenig, B. Khiar, I. Lantu´ ejoul, L. Le-Deroff, B. Reville, R. Rosch, D. Ryu, C. Spindloe, B. Vauzour, B. Villette, A. A. Schekochihin, D. Q. Lamb, P. Tzefera- cos, G. Gregori, and A. Casner, Inefficient Magnetic-Field Amplification in Supersonic Laser-Plasma Turbulence, Phys. Rev. Lett.127,...

  12. [12]

    A. F. A. Bott, P. Tzeferacos, L. Chen, C. A. J. Palmer, A. Rigby, A. R. Bell, R. Bingham, A. Birkel, C. Graziani, D. H. Froula, J. Katz, M. Koenig, M. W. Kunz, C. Li, J. Meinecke, F. Miniati, R. Petrasso, H.-S. Park, B. A. Remington, B. Reville, J. S. Ross, D. Ryu, D. Ryutov, F. H. S´ eguin, T. G. White, A. A. Schekochihin, D. Q. Lamb, and G. Gregori, Tim...

  13. [13]

    Moffatt, Dynamo action associated with random iner- tial waves in a rotating conducting fluid, Journal of Fluid Mechanics44, 705 (1970)

    H. Moffatt, Dynamo action associated with random iner- tial waves in a rotating conducting fluid, Journal of Fluid Mechanics44, 705 (1970)

  14. [14]

    S. I. Vainshtein, Y. B. Zel’dovich,et al., Origin of mag- netic fields in astrophysics (turbulent “dynamo” mecha- nisms), Soviet Physics Uspekhi15, 159 (1972)

  15. [15]

    R. M. Kulsrud and S. W. Anderson, The spectrum of random magnetic fields in the mean field dynamo theory of the galactic magnetic field, Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 396, no. 2, Sept. 10, 1992, p. 606-630.396, 606 (1992)

  16. [16]

    A. A. Schekochihin, S. C. Cowley, G. Hammett, J. Maron, and J. McWilliams, A model of nonlinear evo- lution and saturation of the turbulent mhd dynamo, New Journal of Physics4, 84 (2002)

  17. [17]

    A. A. Schekochihin, S. C. Cowley, S. F. Taylor, J. L. Maron, and J. C. McWilliams, Simulations of the small- scale turbulent dynamo, The Astrophysical Journal612, 276 (2004)

  18. [18]

    Maron, S

    J. Maron, S. Cowley, and J. McWilliams, The nonlinear magnetic cascade, The Astrophysical Journal603, 569 (2004)

  19. [19]

    Schober, D

    J. Schober, D. Schleicher, C. Federrath, R. Klessen, and R. Banerjee, Magnetic field amplification by small- scale dynamo action: Dependence on turbulence mod- els and reynolds and prandtl numbers, Physical Review E—Statistical, Nonlinear, and Soft Matter Physics85, 026303 (2012)

  20. [20]

    Bian and H

    X. Bian and H. Aluie, Decoupled cascades of kinetic and magnetic energy in magnetohydrodynamic turbulence, Physical review letters122, 135101 (2019)

  21. [21]

    Brandenburg and M

    A. Brandenburg and M. Rempel, Reversed dynamo at small scales and large magnetic prandtl number, The As- trophysical Journal879, 57 (2019)

  22. [22]

    Grete, B

    P. Grete, B. W. O’Shea, and K. Beckwith, As a matter of tension: kinetic energy spectra in mhd turbulence, The Astrophysical Journal909, 148 (2021)

  23. [23]

    Kriel, J

    N. Kriel, J. R. Beattie, A. Seta, and C. Federrath, Fun- damental scales in the kinematic phase of the turbulent dynamo, Monthly Notices of the Royal Astronomical So- ciety513, 2457 (2022)

  24. [24]

    Kriel, J

    N. Kriel, J. R. Beattie, C. Federrath, M. R. Krumholz, and J. K. J. Hew, Fundamental mhd scales–ii. the kinematic phase of the supersonic small-scale dynamo, Monthly Notices of the Royal Astronomical Society537, 2602 (2025)

  25. [25]

    J. R. Beattie, C. Federrath, N. Kriel, J. K. J. Hew, and A. Bhattacharjee, Taking control of compressible modes: bulk viscosity and the turbulent dynamo, Monthly No- tices of the Royal Astronomical Society , staf1318 (2025)

  26. [26]

    J. R. Beattie, C. Federrath, R. S. Klessen, S. Cielo, and A. Bhattacharjee, The spectrum of magnetized turbu- lence in the interstellar medium, Nature Astronomy , 1 (2025)

  27. [27]

    A. P. Kazantsev, Enhancement of a Magnetic Field by a Conducting Fluid, Soviet Journal of Experimental and Theoretical Physics26, 1031 (1968)

  28. [28]

    Mach Number Dependence of Turbulent Magnetic Field Amplification: Solenoidal versus Compressive Flows

    C. Federrath, G. Chabrier, J. Schober, R. Banerjee, R. S. Klessen, and D. R. G. Schleicher, Mach Number Dependence of Turbulent Magnetic Field Amplification: Solenoidal versus Compressive Flows, Phys. Rev. Lett. 107, 114504 (2011), arXiv:1109.1760 [physics.flu-dyn]

  29. [29]

    The Turbulent Dynamo in Highly Compressible Supersonic Plasmas

    C. Federrath, J. Schober, S. Bovino, and D. R. G. Schle- icher, The Turbulent Dynamo in Highly Compressible Supersonic Plasmas, Astrophysical Journal Letters797, L19 (2014), arXiv:1411.4707 [astro-ph.GA]

  30. [30]

    Beresnyak, Universal nonlinear small-scale dynamo, Physical Review Letters108, 035002 (2012)

    A. Beresnyak, Universal nonlinear small-scale dynamo, Physical Review Letters108, 035002 (2012)

  31. [31]

    J. Cho, E. T. Vishniac, A. Beresnyak, A. Lazarian, and D. Ryu, Growth of magnetic fields induced by turbulent motions, The Astrophysical Journal693, 1449 (2009)

  32. [32]

    Seta and C

    A. Seta and C. Federrath, Seed magnetic fields in turbu- lent small-scale dynamos, Monthly Notices of the Royal Astronomical Society499, 2076 (2020)

  33. [33]

    A. K. Galishnikova, M. W. Kunz, and A. A. Schekochi- hin, Tearing instability and current-sheet disruption in the turbulent dynamo, Physical Review X12, 041027 (2022)

  34. [34]

    Xu and A

    S. Xu and A. Lazarian, Turbulent dynamo in a conduct- ing fluid and a partially ionized gas, The Astrophysical Journal833, 215 (2016)

  35. [35]

    On the universality of supersonic turbulence

    C. Federrath, On the universality of supersonic turbu- lence, Monthly Notices of the Royal Astronomical Society 436, 1245 (2013), arXiv:1306.3989 [astro-ph.SR]

  36. [36]

    Federrath, R

    C. Federrath, R. S. Klessen, L. Iapichino, and J. R. Beat- tie, The sonic scale of interstellar turbulence, Nature As- tronomy5, 365 (2021), arXiv:2011.06238 [astro-ph.GA]

  37. [37]

    D. R. Schleicher, J. Schober, C. Federrath, S. Bovino, and W. Schmidt, The small-scale dynamo: breaking uni- versality at high mach numbers, New Journal of Physics 15, 023017 (2013)

  38. [38]

    Schober, D

    J. Schober, D. R. Schleicher, C. Federrath, S. Bovino, and R. S. Klessen, Saturation of the turbulent dynamo, Physical Review E92, 023010 (2015)

  39. [39]

    Fryxell, K

    B. Fryxell, K. Olson, P. Ricker, F. X. Timmes, M. Zin- gale, D. Q. Lamb, P. MacNeice, R. Rosner, J. W. Tru- ran, and H. Tufo, FLASH: An Adaptive Mesh Hydrody- namics Code for Modeling Astrophysical Thermonuclear Flashes, The Astrophysical Journal Supplement131, 273 9 (2000)

  40. [40]

    Dubey, R

    A. Dubey, R. Fisher, C. Graziani, G. C. Jordan, IV, D. Q. Lamb, L. B. Reid, P. Rich, D. Sheeler, D. Townsley, and K. Weide, Challenges of Extreme Computing using the FLASH code, inNumerical Modeling of Space Plasma Flows, Astronomical Society of the Pacific Conference Series, Vol. 385, edited by N. V. Pogorelov, E. Audit, and G. P. Zank (2008) p. 145

  41. [41]

    A robust numerical scheme for highly compressible magnetohydrodynamics: Nonlinear stability, implementation and tests

    K. Waagan, C. Federrath, and C. Klingenberg, A ro- bust numerical scheme for highly compressible magne- tohydrodynamics: Nonlinear stability, implementation and tests, Journal of Computational Physics230, 3331 (2011), arXiv:1101.3007 [astro-ph.IM]

  42. [42]

    Federrath, J

    C. Federrath, J. Roman-Duval, R. S. Klessen, W. Schmidt, and M. M. Mac Low, TG: Turbulence Generator, Astrophysics Source Code Library, record ascl:2204.001 (2022)

  43. [43]

    Schekochihin, A

    A. Schekochihin, A. Iskakov, S. Cowley, J. McWilliams, M. Proctor, and T. Yousef, Fluctuation dynamo and tur- bulent induction at low magnetic prandtl numbers, New Journal of Physics9, 300 (2007)

  44. [44]

    A. Seta, P. J. Bushby, A. Shukurov, and T. S. Wood, Saturation mechanism of the fluctuation dynamo at PrM ≥1, Physical Review Fluids5, 043702 (2020), arXiv:2003.07997 [astro-ph.GA]

  45. [45]

    emcee: The MCMC Hammer

    D. Foreman-Mackey, D. W. Hogg, D. Lang, and J. Good- man, emcee: The MCMC Hammer, Proceedings of the Astronomical Society of the Pacific125, 306 (2013), arXiv:1202.3665 [astro-ph.IM]

  46. [46]

    Schober, D

    J. Schober, D. Schleicher, S. Bovino, and R. S. Klessen, Small-scale dynamo at low magnetic prandtl numbers, Physical Review E—Statistical, Nonlinear, and Soft Mat- ter Physics86, 066412 (2012)

  47. [47]

    A complementary model-comparison analysis (see End Matter) confirms that subsonic results are best described by linear growth, while quadratic growth captures the supersonic regime

  48. [48]

    Seta and C

    A. Seta and C. Federrath, Saturation mechanism of the fluctuation dynamo in supersonic turbulent plasmas, Physical Review Fluids6, 103701 (2021)

  49. [49]

    Sur and K

    S. Sur and K. Subramanian, Role of magnetic pressure forces in fluctuation dynamo saturation, Monthly Notices of the Royal Astronomical Society527, 3968 (2024)

  50. [50]

    J. R. Beattie, C. Federrath, R. S. Klessen, S. Cielo, and A. Bhattacharjee, The spectrum of magnetized tur- bulence in the interstellar medium, Nature Astronomy 10.1038/s41550-025-02551-5 (2025), arXiv:2504.07136 [astro-ph.GA]