arxiv: 2605.11894 · v1 · submitted 2026-05-12 · 🌌 astro-ph.HE

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High-energy Neutrino and Gamma Ray Emission from Clusters-like Perseus

Saqib Hussain , Gabrijela Zaharijas , Klaus Dolag

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Pith reviewed 2026-05-13 04:51 UTC · model grok-4.3

classification 🌌 astro-ph.HE

keywords high-energy neutrinosgamma-ray emissiongalaxy clustersPerseus clustercosmic raysintracluster mediummulti-messenger signals

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The pith

Galaxy clusters like Perseus confine cosmic rays long enough to generate detectable high-energy neutrinos and gamma rays from their outskirts.

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

The paper models high-energy neutrino and gamma-ray production in galaxy clusters similar to Perseus that host active galactic nuclei. It demonstrates that cosmic rays remain trapped by the cluster magnetic fields for cosmological timescales and interact with gas and photons to create secondary particles throughout the volume. The resulting diffuse emission from the outskirts is calculated separately from the central AGN and compared against existing IceCube upper limits and CTA sensitivity. The work concludes that such clusters could appear as a new class of multi-messenger sources and contribute to the diffuse neutrino and gamma-ray backgrounds.

Core claim

By propagating cosmic rays through three-dimensional cosmological magnetohydrodynamical simulations of the turbulent intracluster medium and applying multi-dimensional Monte Carlo methods that include all photohadronic, photonuclear, and hadronuclear interactions plus cosmological source evolution, the diffuse emission from the outskirts of Perseus-like clusters can be distinguished from the central AGN and reaches levels that IceCube and CTA could detect while also adding to the diffuse backgrounds.

What carries the argument

Monte Carlo propagation of cosmic rays through MHD-simulated turbulent intracluster medium, incorporating full photohadronic, photonuclear, and hadronuclear interaction channels and cosmological evolution.

Load-bearing premise

Cosmic rays with energies up to 10 to the 17 electronvolts remain confined inside galaxy clusters over cosmological timescales because of the magnetic field configuration in the intracluster medium.

What would settle it

A non-detection of diffuse neutrinos or gamma rays from the outskirts of Perseus by IceCube or CTA, after subtracting any central AGN contribution, at the flux levels predicted by the simulations.

Figures

Figures reproduced from arXiv: 2605.11894 by Gabrijela Zaharijas, Klaus Dolag, Saqib Hussain.

**Figure 2.** Figure 2: Gamma-ray picture of Perseus cluster. Blue band represents our results for parameters 𝛼 = 2.0−2.5 and 𝐸max = 1016 −1017eV. The observations and upper limits for the Perseus cluster by experiments such as MAGIC (red error bars) [16] and LHAASO (brown arrows) [25] are depicted, respectively. The Fermi-LAT upper limits for massive clusters (blue arrows, top to bottom: A400, A3112, A1367, Coma, EXO0422) [? ] a… view at source ↗

**Figure 3.** Figure 3: Multi-messenger picture of Perseus cluster, we represent gamma-rays and neutrino emission. The black and blue lines represent the gamma-ray and neutrino spectra, respectively, for Perseus-like clusters within a distance of 80 Mpc. The results are plotted for 𝛼 = 2.3 & 𝐸max = 1017 eV. The diffuse gamma-ray background observed by Fermi-LAT [23], upper limits predicted by HAWC [24], diffuse neutrino backgroun… view at source ↗

read the original abstract

We calculate the high-energy gamma-ray and neutrino emissions from galaxy clusters like Perseus that host active galactic nuclei (AGNs). Our primary objective is to distinguish the emission from the central source, such as NGC$1275$, from the diffuse emission originating in the outskirts of the Perseus cluster. Due to a unique magnetic-field configuration, CRs with energy $\leq 10^{17}$ eV can be confined within these structures over cosmological time scales, and generate secondary particles, including neutrinos and gamma-rays, through interactions with the background gas and photons. We employ three-dimensional cosmological magnetohydrodynamical simulations of structure formation to model the turbulent intracluster medium (ICM). We propagate CRs in intracluster medium (ICM) and intergalactic medium using multi-dimensional Monte Carlo simulations, considering all relevant photohadronic, photonuclear, and hadronuclear interactions. We also include the cosmological evolution of sources like Perseus. By comparing our results with the existing upper limits from IceCube for galaxy clusters and the sensitivity of CTA, we predict that these observatories could potentially establish a new class of astrophysical sources capable of emitting high-energy multi-messenger signals. We also compute the contribution from clusters like Perseus to the diffuse neutrino and gamma-ray background.

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 models diffuse neutrino and gamma-ray emission from Perseus-like clusters by separating central AGN from outskirts but the CR confinement claim over cosmological times looks under-supported.

read the letter

The core takeaway is that this work applies standard 3D MHD cluster simulations and Monte Carlo CR transport to predict multi-messenger signals from systems like Perseus, with explicit separation of the central source from the diffuse component and some cosmological evolution included. It then compares those predictions against IceCube cluster limits and CTA sensitivity while estimating the contribution to the diffuse backgrounds. That separation and the full interaction set are the parts that feel like a useful incremental step beyond earlier cluster studies. The methods themselves are established, so the execution looks competent on the modeling side. The soft spot sits right where the stress-test flagged it. The predictions require that protons up to 10^17 eV stay trapped long enough for secondary production to matter, which the abstract attributes to a unique ICM magnetic-field configuration. Standard Bohm diffusion estimates give residence times orders of magnitude shorter than a Hubble time, so the paper needs to show the actual escape fractions or diffusion coefficients extracted from the simulated fields. If those numbers are not reported or if they still fall short, the flux predictions lose their grounding. The abstract supplies no quantitative results or error bars, which makes it hard to judge how much the confinement assumption drives the final numbers. This is the kind of paper that belongs in the multi-messenger astrophysics pile. Readers working on neutrino backgrounds or cluster CR physics would get value from the setup and the central-versus-diffuse split, even if they end up disagreeing with the confinement premise. It is coherent enough on its own terms to deserve a serious referee rather than a desk reject, provided the authors can supply the residence-time diagnostics. I would send it out for review with a note to focus on that point.

Referee Report

2 major / 2 minor

Summary. The manuscript calculates high-energy neutrino and gamma-ray emissions from Perseus-like galaxy clusters hosting AGNs. It models the turbulent ICM with 3D cosmological MHD simulations, propagates CRs via multi-dimensional Monte Carlo methods including all photohadronic, photonuclear, and hadronuclear interactions, and incorporates source cosmological evolution. The central claim is that a unique ICM magnetic-field configuration confines CRs with E ≤ 10^17 eV over cosmological timescales, producing detectable diffuse secondaries distinguishable from central sources like NGC 1275; these emissions are compared to IceCube cluster limits and CTA sensitivity, with predictions for a new multi-messenger source class and contributions to the diffuse neutrino and gamma-ray backgrounds.

Significance. If the confinement assumption is validated, the work would be significant for multi-messenger astrophysics by identifying galaxy clusters as potentially detectable high-energy neutrino and gamma-ray sources separate from their central AGNs, while quantifying their role in diffuse backgrounds. The approach benefits from full 3D MHD structure-formation simulations, comprehensive interaction physics in the Monte Carlo propagation, and explicit inclusion of source evolution, which are strengths that could support falsifiable predictions once quantitative escape-time results are provided.

major comments (2)

[Abstract / CR propagation section] Abstract and CR confinement discussion: the claim that CRs with E ≤ 10^17 eV remain confined over cosmological timescales due to a 'unique magnetic-field configuration' in the ICM is load-bearing for all flux predictions, yet no explicit residence-time distributions, escape fractions, or interaction optical depths from the Monte Carlo runs are reported to demonstrate t_escape ≳ 10^9 yr; standard Bohm-diffusion estimates in μG fields yield t_diff ~ 10^6–10^7 yr, so the simulated fields must be shown to suppress escape sufficiently for appreciable pp and photopion production.
[Monte Carlo propagation methods] Methods on Monte Carlo propagation: without tabulated escape times or optical-depth results as a function of energy and cluster radius (e.g., analogous to a table of residence times), it is impossible to verify that the predicted neutrino and gamma-ray fluxes are not overestimated by orders of magnitude; this directly affects the comparison to IceCube limits and the diffuse-background contribution claim.

minor comments (2)

[Abstract] Abstract supplies no quantitative flux values, error bars, or specific IceCube/CTA comparison numbers, making it difficult to assess the strength of the 'potentially establish a new class' prediction without reading the full results section.
[Introduction / Methods] Notation for the magnetic-field configuration and the precise energy threshold (10^17 eV) should be defined with a reference to the simulation output or an equation showing how the 'unique' topology is quantified.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful and constructive review of our manuscript. The concerns about explicitly demonstrating cosmic-ray confinement times are valid and central to the robustness of our predictions. We will revise the paper to include the requested quantitative outputs from the Monte Carlo simulations.

read point-by-point responses

Referee: [Abstract / CR propagation section] Abstract and CR confinement discussion: the claim that CRs with E ≤ 10^17 eV remain confined over cosmological timescales due to a 'unique magnetic-field configuration' in the ICM is load-bearing for all flux predictions, yet no explicit residence-time distributions, escape fractions, or interaction optical depths from the Monte Carlo runs are reported to demonstrate t_escape ≳ 10^9 yr; standard Bohm-diffusion estimates in μG fields yield t_diff ~ 10^6–10^7 yr, so the simulated fields must be shown to suppress escape sufficiently for appreciable pp and photopion production.

Authors: We agree that the confinement claim requires explicit support from the simulation outputs. Our 3D MHD structure-formation simulations produce a turbulent ICM magnetic-field geometry that is not captured by uniform-field Bohm-diffusion estimates; particle trajectories in this tangled, volume-filling field yield longer residence times. The Monte Carlo propagation code tracks these trajectories and all interaction channels, but we did not extract or tabulate the residence-time statistics in the submitted version. In the revision we will add a new subsection (with accompanying figure and table) that reports escape-time distributions, escape fractions, and interaction optical depths as functions of energy and cluster-centric radius. These data will directly demonstrate that the average t_escape for E ≤ 10^17 eV exceeds 10^9 yr under the simulated field configuration. revision: yes
Referee: [Monte Carlo propagation methods] Methods on Monte Carlo propagation: without tabulated escape times or optical-depth results as a function of energy and cluster radius (e.g., analogous to a table of residence times), it is impossible to verify that the predicted neutrino and gamma-ray fluxes are not overestimated by orders of magnitude; this directly affects the comparison to IceCube limits and the diffuse-background contribution claim.

Authors: We accept that the absence of these tabulated quantities limits independent verification of the flux normalizations. Although the Monte Carlo runs internally accumulate particle histories that include escape times and optical depths, these diagnostics were not reported. We will revise the Methods section to include representative tables and plots of residence times and optical depths versus energy and radius. This addition will allow readers to confirm that the secondary fluxes are not overestimated and will strengthen the comparisons to IceCube cluster limits and the diffuse-background estimates. revision: yes

Circularity Check

0 steps flagged

No significant circularity in derivation chain

full rationale

The paper performs forward modeling using 3D cosmological MHD simulations of structure formation to generate the turbulent ICM and its magnetic-field configuration. CR propagation is then carried out via multi-dimensional Monte Carlo simulations that incorporate photohadronic, photonuclear, and hadronuclear interactions, cosmological source evolution, and secondary production of neutrinos and gamma rays. The claimed confinement of CRs ≤ 10^17 eV over cosmological timescales is stated as a consequence of the simulated fields rather than an a-priori definition or fitted input. Resulting fluxes are compared to external IceCube upper limits and CTA sensitivity curves; the diffuse-background contribution is likewise computed from the same simulation pipeline. No step reduces a prediction to a fitted parameter, a self-citation chain, or an ansatz smuggled via prior work by the same authors. The derivation is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

Central claim depends on assumptions about long-term CR confinement and the fidelity of MHD turbulence modeling; no new particles or forces are postulated.

free parameters (2)

CR confinement energy threshold
Stated as ≤10^17 eV based on assumed magnetic field configuration; value chosen to enable cosmological trapping.
Source evolution parameters for clusters like Perseus
Cosmological evolution of AGN and cluster sources is included but normalization and redshift dependence not specified in abstract.

axioms (2)

domain assumption Cosmic rays below 10^17 eV remain confined in cluster magnetic fields over cosmological timescales
Invoked to justify secondary particle production in the ICM and IGM.
standard math All relevant photohadronic, photonuclear, and hadronuclear interactions are modeled in the Monte Carlo propagation
Standard assumption in high-energy CR transport codes.

pith-pipeline@v0.9.0 · 5533 in / 1484 out tokens · 87627 ms · 2026-05-13T04:51:37.835818+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

34 extracted references · 34 canonical work pages

[1]

Di Mauro et al.Astrophys

M. Di Mauro et al.Astrophys. J.780, 161 (2013)

work page 2013
[2]

Ajello et al.Astrophys

M. Ajello et al.Astrophys. J. L.800, L27 (2015)

work page 2015
[3]

Fang and K

K. Fang and K. Murase,Nat. Phys.14, 396 (2018)

work page 2018
[4]

Hussain et al.Mon

S. Hussain et al.Mon. Not. R. Astron. Soc.507, 1762 (2021)

work page 2021
[5]

Hussain et al.Nat

S. Hussain et al.Nat. Commun.14, 2486 (2023)

work page 2023
[6]

M. A. Roth et al.Nature597, 341 (2021)

work page 2021
[7]

Eagle et al.Astrophys

J. Eagle et al.Astrophys. J.945, 4 (2023)

work page 2023
[8]

arXiv preprint arXiv:2208.13792 , year=

F. Lucarelli et al.arXiv:2208.13792(2022)

work page arXiv 2022
[9]

Pagliaroli, et al.Universe, 9(9),381(2023)

G. Pagliaroli, et al.Universe, 9(9),381(2023)

work page 2023
[10]

de Menezes et al.Astrophys

R. de Menezes et al.Astrophys. J.933, 213 (2022)

work page 2022
[11]

O., Urban, O., et al.Mon. Not. of the R. Astron. Soc.437(2014)

work page 2014
[12]

T., Nhut, et al.,A& A686(2024)

work page 2024
[13]

Cao et al

Z. Cao et al. LHAASO Collaboration,Astrophys. J. L.982, L19 (2025)

work page 2025
[14]

Dolag et al.A&A,677, A169 (2023)

K. Dolag et al.A&A,677, A169 (2023)

work page 2023
[15]

R. B. Tully et al.Astrophys. J.944, 94 (2023)

work page 2023
[16]

M. L. Ahnen et al. MAGIC CollaborationA&A589, A33 (2016). 6 High-energy Neutrino and Gamma Ray Emission from Clusters-like PerseusSaqib Hussain

work page 2016
[17]

Hussain et al.Astrophys

S. Hussain et al.Astrophys. J.,960, 124, (2024)

work page 2024
[18]

Alves Batista et al.,J

R. Alves Batista et al.,J. Cosmol. Astropart. Phys.1605, 038 (2016)

work page 2016
[19]

Fang and A

K. Fang and A. V. Olinto,Astrophys. J.828, 37 (2016)

work page 2016
[20]

Aartsen et al.Astropart

M. Aartsen et al.Astropart. phys.66, 39 (2015)

work page 2015
[21]

Ackermann et al.Astrophys

M. Ackermann et al.Astrophys. J.787, 18 (2014)

work page 2014
[22]

M. G. Aartsen et al.Phys. Rev. L.115, 081102 (2015)

work page 2015
[23]

Ackermann et al.Astrophys

M. Ackermann et al.Astrophys. J.799, 86 (2015)

work page 2015
[24]

arXiv preprint arXiv:2209.08106 , year=

A. Albert et al.arXiv:2209.08106(2022)

work page arXiv 2022
[25]

and Part

LHAASO Collaboration et al.,Nucl. and Part. Phys. Proc.279, 166 (2016)

work page 2016
[26]

CTAConsortiumetal.,SciencewiththeCherenkovTelescopeArray(WorldScientific,2018)

work page 2018
[27]

Sinitsyna and V

V. Sinitsyna and V. Y. Sinitsyna,Astron. L.40, 75 (2014)

work page 2014
[28]

Abdu Halim et al.JCAP,01, 022 (2024)

A. Abdu Halim et al.JCAP,01, 022 (2024)

work page 2024
[29]

Kotera et al.Astrophys

K. Kotera et al.Astrophys. J.707, 370 (2009)

work page 2009
[30]

Jui, in Proc

C. Jui, in Proc. Sci.34th International Cosmic Ray Conference(2015)

work page 2015
[31]

Aab, in Proc

A. Aab, in Proc. Sci.34th International Cosmic Ray Conference(2015)

work page 2015
[32]

Abbasi et al.Astrophys

R. Abbasi et al.Astrophys. J. L.938, L11 (2022)

work page 2022
[33]

Neronov, et al.Phys

A. Neronov, et al.Phys. Rev. D,108103008 (2023)

work page 2023
[34]

Kim et al.EPJ Web of Conferences283, 03005 (2023) 7

J. Kim et al.EPJ Web of Conferences283, 03005 (2023) 7

work page 2023