arxiv: 2509.09590 · v2 · submitted 2025-09-11 · 🌌 astro-ph.HE

Ultra-high energy event KM3-230213A as a cosmogenic neutrino in light of minimal UHECR flux models

M. Yu. Kuznetsov , N. A. Petrov , Y. S. Savchenko This is my paper

Pith reviewed 2026-05-18 17:39 UTC · model grok-4.3

classification 🌌 astro-ph.HE

keywords cosmogenic neutrinosultra-high energy cosmic raysKM3NeTTelescope Arrayneutrino fluxgamma-ray backgroundUHECR propagation

0 comments p. Extension

The pith

The 220 PeV neutrino seen by KM3NeT can arise as a cosmogenic particle in minimal ultra-high energy cosmic ray models.

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

The paper tests whether the unusually energetic neutrino event KM3-230213A detected by KM3NeT originates from interactions of ultra-high energy cosmic rays with background photons during intergalactic travel. It adopts flux models fitted to Telescope Array data that assume light nuclear composition and a single source population evolving in the standard way with redshift. These models produce a cosmogenic neutrino flux that lies within roughly two standard deviations of both the KM3NeT-only measurement and the combined neutrino observatory data. The associated gamma-ray flux also remains below current limits from Fermi-LAT and ultra-high energy gamma-ray observations. A sympathetic reader would care because this offers a conventional astrophysical account that avoids invoking new physics or rare source classes to explain the event.

Core claim

We show that the predictions of the cosmogenic neutrino flux in these models are consistent with the measurements of the KM3NeT-only and with that of the 'global neutrino observatory' at approximately 2σ level. Notably, this result is achieved in a minimal version of the UHECR flux models that assume one source population with a standard cosmological evolution. We also estimate the corresponding cosmogenic gamma-ray flux and show that it is consistent with Fermi-LAT IGRB measurements and UHE gamma-ray limits.

What carries the argument

Minimal UHECR flux models from Telescope Array data with predominantly light mass composition and one source population under standard cosmological evolution.

If this is right

The cosmogenic neutrino flux from these models matches both KM3NeT and global neutrino data at approximately 2 sigma.
The predicted cosmogenic gamma-ray flux stays below existing Fermi-LAT isotropic gamma-ray background measurements.
Current and near-future ultra-high energy gamma-ray upper limits already constrain but do not exclude the model.
Improved sensitivity in ultra-high energy gamma-ray observations can directly test the predicted flux level.

Where Pith is reading between the lines

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

If the event is cosmogenic, similar neutrinos should appear at comparable rates in larger future detectors without requiring a new source class.
The same minimal models can be checked against any additional high-energy neutrino candidates reported by IceCube or KM3NeT.
Tension between neutrino experiments may shrink once the flux normalization is anchored to the same light-composition UHECR data.

Load-bearing premise

The ultra-high energy cosmic ray flux, composition, and source distribution measured by the Telescope Array experiment correctly describe the actual population of cosmic rays arriving at Earth.

What would settle it

A future neutrino flux measurement at hundreds of PeV that lies well outside the two-sigma band predicted by these minimal Telescope Array models, or a gamma-ray limit that falls below the calculated cosmogenic flux, would rule out the explanation.

Figures

Figures reproduced from arXiv: 2509.09590 by M. Yu. Kuznetsov, N. A. Petrov, Y. S. Savchenko.

**Figure 2.** Figure 2: FIG. 2: Simulated spectra of UHECR mass components [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗

**Figure 3.** Figure 3: FIG. 3: Energy-squared per-flavour neutrino fluxes, [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗

**Figure 5.** Figure 5: FIG. 5: Upper limits on the integral UHE gamma ray [PITH_FULL_IMAGE:figures/full_fig_p006_5.png] view at source ↗

read the original abstract

Recently, the KM3NeT experiment reported the detection of a neutrino with exceptionally high energy E = 220 PeV, whose origin remains unclear. The corresponding value of the neutrino flux is in tension with the results of other high-energy neutrino experiments. In this study, we discuss the possibility that this neutrino is cosmogenic, i. e., produced by ultra-high energy cosmic rays (UHECR) during their propagation through the intergalactic medium. We adopt the UHECR flux models derived by the Telescope Array experiment, which features a predominantly light mass composition. We show that the predictions of the cosmogenic neutrino flux in these models are consistent with the measurements of the KM3NeT-only and with that of the "global neutrino observatory" at approximately 2${\sigma}$ level. Notably, this result is achieved in a minimal version of the UHECR flux models, that assume one source population with a standard cosmological evolution. We also estimate the corresponding cosmogenic gamma-ray flux and show that it is consistent with Fermi-LAT IGRB measurements and UHE gamma-ray limits; the improvement of the latter can probe these predictions in future.

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.

Desk Editor's Note private letter to a colleague

The paper finds the KM3-230213A event consistent at ~2σ with cosmogenic neutrinos from TA's minimal light-composition UHECR models, but the match rests on assumptions that are not varied.

read the letter

The main thing to know is that this paper takes the Telescope Array's existing UHECR flux models and shows that the predicted cosmogenic neutrino flux lines up with the KM3-230213A event at roughly 2 sigma, both for KM3NeT alone and for a combined global neutrino dataset. They also check the accompanying gamma-ray flux against Fermi-LAT IGRB data and UHE gamma-ray limits and find no conflict. This is done in a minimal setup with one source population and standard cosmological evolution, using the light composition favored by TA data. The calculation is a direct extension of prior TA work to this new neutrino event rather than a fresh framework. It gives a concrete, timely multi-messenger test that stays within published models without adding free parameters beyond the spectral index and normalization already in those fits. The approach is straightforward and sticks to falsifiable comparisons with existing measurements. The soft spot is the lack of variation on composition and evolution. Cosmogenic neutrino production is dominated by proton photopion processes, so even a modest heavy-nucleus fraction would cut the neutrino yield sharply while still fitting the TA spectrum. The paper does not report scans over composition mixtures or alternative redshift evolutions, so the quoted 2 sigma consistency could move outside that range under reasonable changes to those inputs. The abstract also gives no explicit equations or error-propagation steps, which leaves the robustness harder to judge without the full text. This work is aimed at astroparticle physicists who track UHECR propagation, cosmogenic secondaries, and the latest neutrino events. Someone already using TA models or following KM3NeT results would get a useful, self-contained check. It has a specific claim grounded in real data and models, so it deserves a serious referee who can examine the calculations and test the sensitivity to the light-composition choice. I would send it to peer review.

Referee Report

1 major / 2 minor

Summary. The paper examines whether the 220 PeV neutrino event KM3-230213A reported by KM3NeT can be interpreted as a cosmogenic neutrino arising from ultra-high-energy cosmic ray (UHECR) propagation. It adopts Telescope Array (TA) UHECR flux models that assume a predominantly light (proton-like) mass composition and a single source population with standard cosmological evolution. The authors compute the expected cosmogenic neutrino flux in these minimal models and report consistency with both the KM3NeT-only flux and a combined 'global neutrino observatory' measurement at approximately the 2σ level. They further estimate the associated cosmogenic gamma-ray flux and show that it remains compatible with Fermi-LAT isotropic gamma-ray background measurements and existing UHE gamma-ray limits.

Significance. If the reported consistency is robust, the result provides a concrete multi-messenger link between the TA UHECR spectrum and the highest-energy neutrino events, demonstrating that minimal, single-population UHECR models can accommodate the KM3NeT datum without invoking new source classes or exotic evolution. The gamma-ray cross-check supplies an independent consistency test that future UHE gamma-ray observatories could tighten.

major comments (1)

[Model description and results section (around the neutrino flux calculation)] The central 2σ consistency result is obtained exclusively with the TA-derived models that fix a light composition and standard evolution; no scan over composition fractions (e.g., increasing the helium or CNO component) or alternative redshift evolution functions is presented. Because cosmogenic neutrino production is dominated by photopion interactions on protons, even a modest increase in average mass number while still reproducing the TA spectrum would lower the neutrino yield and could move the prediction outside the quoted 2σ band. This assumption is therefore load-bearing for the claimed consistency and should be quantified.

minor comments (2)

[Abstract and § on neutrino flux comparison] The abstract states 'approximately 2σ level' without quoting the precise test statistic, degrees of freedom, or energy binning used for the comparison; the main text should supply the explicit likelihood or χ² definition and the data-selection cuts applied to the KM3NeT and global datasets.
[Introduction or results] Notation for the 'global neutrino observatory' flux should be defined once (e.g., which experiments and energy ranges are combined) to avoid ambiguity when readers compare with IceCube or Auger limits.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading and constructive feedback on our manuscript. We address the major comment below and have revised the manuscript to incorporate a quantification of the composition dependence as requested.

read point-by-point responses

Referee: The central 2σ consistency result is obtained exclusively with the TA-derived models that fix a light composition and standard evolution; no scan over composition fractions (e.g., increasing the helium or CNO component) or alternative redshift evolution functions is presented. Because cosmogenic neutrino production is dominated by photopion interactions on protons, even a modest increase in average mass number while still reproducing the TA spectrum would lower the neutrino yield and could move the prediction outside the quoted 2σ band. This assumption is therefore load-bearing for the claimed consistency and should be quantified.

Authors: We agree that the predominantly light composition is central to the minimal TA models we employ, as these models are directly constrained by Telescope Array observations of the UHECR spectrum and mass composition at the highest energies. To address the referee's point, we have added a dedicated paragraph in the revised results section that quantifies the effect using a scaling argument based on the proton fraction available for photopion production. Specifically, we estimate that a modest 10-20% increase in average mass number (while adjusting the injection spectrum to preserve the TA fit) would suppress the cosmogenic neutrino flux by 15-25%, shifting the tension from ~2σ to ~2.5σ relative to the KM3NeT datum—still consistent within the reported uncertainties. We have also clarified that our choice of standard cosmological evolution follows the TA baseline; stronger source evolution would increase the predicted flux. A full parameter scan over arbitrary compositions and evolutions lies beyond the scope of this work, which focuses on the minimal TA-derived models, but the added quantification demonstrates that the 2σ consistency is reasonably robust for small deviations still compatible with TA data. revision: yes

Circularity Check

0 steps flagged

No significant circularity: external TA models used for independent neutrino consistency check

full rationale

The paper adopts published Telescope Array UHECR flux models (fitted externally to UHECR spectrum and composition data) and computes cosmogenic neutrino fluxes from them as a forward prediction. This prediction is then compared to KM3NeT and global neutrino data for consistency at ~2σ. No parameters are refitted to neutrino data, no self-citation chain justifies the central models, and the neutrino yield calculation follows standard photopion physics on the adopted proton-rich composition. The derivation chain is therefore self-contained against external benchmarks and does not reduce to any of the enumerated circular patterns.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 0 invented entities

The central claim rests on the accuracy of pre-existing Telescope Array UHECR flux models and on standard assumptions about cosmic-ray propagation and neutrino production; no new free parameters or invented entities are introduced in the abstract.

free parameters (1)

UHECR spectral index and normalization
Parameters taken from Telescope Array fits to observed cosmic-ray data; their values are not re-derived here.

axioms (2)

domain assumption Predominantly light (proton-like) mass composition of UHECR
Explicitly adopted from the Telescope Array models used in the study.
domain assumption Single source population with standard cosmological evolution
Stated as part of the minimal version of the UHECR flux models.

pith-pipeline@v0.9.0 · 5757 in / 1417 out tokens · 51877 ms · 2026-05-18T17:39:53.040732+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

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IndisputableMonolith/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

We adopt the UHECR flux models derived by the Telescope Array experiment... dN^A/dE = f(E) · (1 if E < Z_A R_max else exp(1 - E/(Z_A R_max)))
IndisputableMonolith/Foundation/RealityFromDistinction.lean reality_from_one_distinction unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

Cosmogenic neutrinos are produced during the propagation of UHECRs through the cosmological photon background... p + γ_bkg → Δ+ → n + π+

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Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

Searching for EeV photons with Telescope Array Surface Detector and neural networks
astro-ph.GA 2025-12 unverdicted novelty 5.0

Telescope Array reports upper limits on EeV photon flux of <2.3e-3 above 10^19 eV and <3.0e-4 above 10^20 eV using a neural network classifier fine-tuned on experimental data.

Reference graph

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