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arxiv: 2606.17490 · v1 · pith:VJNLJVRZnew · submitted 2026-06-16 · 🌌 astro-ph.HE · astro-ph.GA

Revisiting Disk Winds in Active Galactic Nuclei as an Origin of Cosmic Gamma-ray and Neutrino Backgrounds

Nobuyuki Sakai , Yoshiyuki Inoue , Ellis R. Owen This is my paper

Pith reviewed 2026-06-27 00:00 UTC · model grok-4.3

classification 🌌 astro-ph.HE astro-ph.GA
keywords active galactic nucleidisk windscosmic gamma-ray backgroundcosmic neutrino backgroundlepto-hadronic emissionSeyfert galaxiesultrafast outflowspopulation synthesis
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The pith

AGN disk winds contribute at most 5% of the cosmic gamma-ray background above 10 GeV and 10% of the neutrino background near 100 TeV.

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

Active galactic nuclei launch disk winds that can accelerate cosmic rays at forward and reverse shocks, leading to gamma-ray and neutrino production through synchrotron, external-Compton, and hadronic processes. Estimates of their contribution to the cosmic backgrounds have varied widely because wind speeds, energetics, and surrounding densities remain uncertain. This study builds lepto-hadronic models fitted to radio and GeV gamma-ray data from nearby Fermi-LAT detected Seyfert galaxies and recent XRISM wind measurements. Scaling the calibrated models across an AGN population synthesis shows that winds supply no more than a few percent of either background. Other source classes must therefore supply the bulk of the observed cosmic gamma rays and neutrinos.

Core claim

Lepto-hadronic models of AGN disk winds, with cosmic rays accelerated at wind-driven shocks and emission components calibrated to nearby Seyfert observations plus XRISM constraints, when applied to a full AGN population synthesis, yield at most ≲5% of the CGB above 10 GeV and ≲10% of the CNB around 100 TeV.

What carries the argument

Lepto-hadronic wind model in which cosmic rays at forward and reverse shocks produce synchrotron, external-Compton, and hadronic emission, calibrated to radio and GeV data of nearby Seyferts.

If this is right

  • Disk winds are unlikely to dominate either the cosmic gamma-ray or neutrino backgrounds.
  • Nearby Seyfert galaxies with ultrafast outflows become priority targets for TeV gamma-ray and TeV-PeV neutrino telescopes.
  • The small predicted fluxes imply that multi-messenger searches for AGN winds must reach deeper sensitivities to test the scenario.
  • The conclusion holds within the range of parameters allowed by current radio, GeV, and XRISM constraints.

Where Pith is reading between the lines

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

  • If the calibrated model is accurate, the dominant contributors to both backgrounds must lie outside the disk-wind channel, such as other AGN structures or entirely different source populations.
  • Future population studies could test the result by varying the redshift evolution of wind parameters independently of the local calibration sample.
  • Non-detections at TeV energies from the proposed nearby targets would strengthen the case that winds remain sub-dominant even in the most favorable objects.

Load-bearing premise

Wind energetics, ambient densities, and the assumption that parameters fitted to a handful of nearby Seyferts apply uniformly to the entire AGN population at all redshifts.

What would settle it

A measured contribution from disk winds exceeding 5% of the CGB above 10 GeV or 10% of the CNB near 100 TeV in population-level data, or TeV gamma-ray detections from nearby ultrafast-outflow Seyferts well above the model's predicted flux, would falsify the low-contribution result.

Figures

Figures reproduced from arXiv: 2606.17490 by Ellis R. Owen, Nobuyuki Sakai, Yoshiyuki Inoue.

Figure 1
Figure 1. Figure 1: Timescales for CR acceleration, advection, and energy losses in the SAM and SW regions, computed using the fiducial parameters listed in [PITH_FULL_IMAGE:figures/full_fig_p005_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: SEDs of the multiwavelength photon and neutrino emission from CRs accelerated by an AGN disk wind. Calculations adopt a redshift of z = 0.02 and the fiducial parameters in [PITH_FULL_IMAGE:figures/full_fig_p007_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Parameter dependence of the SEDs. In all panels, thick solid lines, thin dotted lines, thin dashed-dotted lines, and thick dashed lines represent total gamma rays, gamma rays from the SW via EC scattering, those from the SAM via pp interactions, and the sum of neutrinos and antineutrinos per flavor from the SAM via pp interactions, respectively. Top-Left: Dependence on the boost factor bw. Blue, orange, an… view at source ↗
Figure 4
Figure 4. Figure 4: Multiwavelength SEDs of photons and neutrinos (ν + ¯ν per flavor) of the Circinus galaxy, NGC 4945, NGC 4151, NGC 1068, and GRS 1734-292 from top-left to bottom right. In all panels, solid and dashed blue (orange) lines show total gamma-ray and neutrino fluxes in Model A (B). Gray, green, and purple data points are archival data from NASA/IPAC Extragalactic Database (NED) (2019), the 4FGL-DR4 catalog of Fe… view at source ↗
Figure 5
Figure 5. Figure 5: Cosmic gamma-ray (solid) and neutrino (dashed) background intensities from AGN disk winds. For neutrinos, we show the total emission, summed over all flavors. Blue and orange curves correspond to our Model A (leptonic dominated) and Model B (hadronic dominated), respectively. For the model parameters, we adopt the median values listed in [PITH_FULL_IMAGE:figures/full_fig_p013_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Same as [PITH_FULL_IMAGE:figures/full_fig_p013_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: The dependence of the background intensities on the ISM index β. We show the expected CGB and CNB intensities in the cases of β = 1 (blue, our fiducial value), β = 0 (orange), β = 11/7 (green), and β = 2 (red) for Model B. The line styles and data points are the same as [PITH_FULL_IMAGE:figures/full_fig_p016_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Comparison between the results obtained in this work and previous studies. Thick solid and thin dashed lines show gamma-ray and neutrino intensities, respectively. The blue lines correspond to Model A in this study. Other lines show the background prediction by X. Wang & A. Loeb (2016a, orange), A. Lamastra et al. (2017, purple), and R.-Y. Liu et al. (2018, brown). Differences in the intensities predicted … view at source ↗
Figure 9
Figure 9. Figure 9: Same as [PITH_FULL_IMAGE:figures/full_fig_p019_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Same as [PITH_FULL_IMAGE:figures/full_fig_p021_10.png] view at source ↗
read the original abstract

The origin of the cosmic neutrino background (CNB) and the cosmic gamma-ray background (CGB) remains uncertain. Accretion disk winds driven by active galactic nuclei (AGNs) have been proposed as possible contributors, but their predicted background levels depend sensitively on poorly constrained wind energetics and ambient densities. We revisit the AGN disk-wind scenario by constructing a lepto-hadronic wind model calibrated with radio and GeV gamma-ray data of nearby Fermi-LAT-detected Seyfert galaxies. In our framework, cosmic rays accelerated both at wind-driven forward and reverse shocks produce synchrotron, external-Compton, and hadronic emission. We also incorporate recent XRISM constraints on wind parameters. Applying our calibrated lepto-hadronic models to an AGN population synthesis model, we find that disk winds contribute at most $\lesssim 5\%$ of the CGB above 10 GeV and $\lesssim 10\%$ of the CNB around 100 TeV, suggesting that they are unlikely to dominate both backgrounds. Finally, we identify nearby Seyfert galaxies hosting ultrafast outflows as promising targets for future TeV gamma-ray and TeV$-$PeV neutrino observations, which would offer firm tests of the disk-wind scenario.

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 / 1 minor

Summary. The manuscript constructs a lepto-hadronic model for AGN accretion disk winds, calibrated using radio and GeV gamma-ray observations of nearby Fermi-LAT detected Seyfert galaxies along with XRISM constraints on wind parameters. The model includes cosmic ray acceleration at forward and reverse shocks producing synchrotron, external-Compton, and hadronic emission. This calibrated model is then applied to an AGN population synthesis to compute contributions to the cosmic gamma-ray background (CGB) and cosmic neutrino background (CNB), yielding upper limits of ≲5% for the CGB above 10 GeV and ≲10% for the CNB around 100 TeV. The authors conclude that disk winds are unlikely to dominate these backgrounds and suggest nearby Seyferts with ultrafast outflows as targets for future observations.

Significance. If the central upper limits hold under the model's assumptions, the result is significant as it constrains the role of AGN disk winds in the diffuse backgrounds, indicating that other source classes must dominate. The calibration to multi-wavelength data from nearby objects and the use of population synthesis provide a concrete framework for such estimates. The identification of specific targets for TeV and neutrino observations adds value for future tests. The strength depends on the validity of extrapolating local calibrations to the full population.

major comments (2)
  1. [§3] §3: The assumption that wind kinetic power, ambient density, and acceleration efficiency calibrated on a small sample of nearby Fermi-LAT Seyferts apply uniformly to the full AGN population synthesis at all redshifts is load-bearing for the quoted ≲5% CGB and ≲10% CNB limits. No sensitivity analysis is presented for plausible variations with bolometric luminosity, Eddington ratio, or redshift (as hinted by XRISM surveys), which could raise the integrated backgrounds without violating the local fit.
  2. [Abstract and §3] Abstract and §3: The abstract states that wind energetics and densities are 'poorly constrained' prior to the fit; after calibration the upper limits are reported without propagating the small calibration sample size into uncertainties on the population-integrated fractions, weakening the claim that winds are 'unlikely to dominate'.
minor comments (1)
  1. The lepto-hadronic emission components (synchrotron, external-Compton, hadronic) would benefit from a short dedicated subsection clarifying the target photon fields and shock properties for readers outside the immediate subfield.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the detailed and constructive report. We address the two major comments point by point below, indicating planned revisions where appropriate.

read point-by-point responses

  1. Referee: [§3] The assumption that wind kinetic power, ambient density, and acceleration efficiency calibrated on a small sample of nearby Fermi-LAT Seyferts apply uniformly to the full AGN population synthesis at all redshifts is load-bearing for the quoted ≲5% CGB and ≲10% CNB limits. No sensitivity analysis is presented for plausible variations with bolometric luminosity, Eddington ratio, or redshift (as hinted by XRISM surveys), which could raise the integrated backgrounds without violating the local fit.

    Authors: We agree that uniform extrapolation of the locally calibrated parameters is a central assumption. The calibration draws on the best-constrained nearby Seyferts with radio and GeV data, and we have already folded in XRISM wind-parameter constraints. While redshift or Eddington-ratio dependence cannot be ruled out, the model is constructed to yield conservative upper limits. We will add a dedicated sensitivity analysis in §3 that varies wind kinetic power, ambient density, and acceleration efficiency over ranges allowed by XRISM and other surveys, while preserving the local fits, and will report the resulting range of background contributions. revision: yes

  2. Referee: [Abstract and §3] The abstract states that wind energetics and densities are 'poorly constrained' prior to the fit; after calibration the upper limits are reported without propagating the small calibration sample size into uncertainties on the population-integrated fractions, weakening the claim that winds are 'unlikely to dominate'.

    Authors: The calibration sample is small by necessity (Fermi-LAT-detected Seyferts with radio coverage), and we acknowledge that formal propagation of sample-size uncertainty would strengthen the error budget. The reported ≲5% and ≲10% figures are already framed as upper limits from the best-fit model rather than central values. We will revise the abstract and the relevant paragraph in §3 to explicitly note the limited sample size and the conservative nature of the limits, while retaining the conclusion that even these upper bounds indicate disk winds are unlikely to dominate. revision: partial

Circularity Check

0 steps flagged

No significant circularity; calibration to independent local data then extrapolated

full rationale

The paper calibrates lepto-hadronic parameters (wind power, density, efficiency) to radio/GeV observations of nearby Fermi-LAT Seyferts plus XRISM constraints, then integrates the fixed model over an external AGN population synthesis to obtain background fractions. This is an application of fitted parameters to a separate dataset, not a fit to the target CGB/CNB or a self-referential definition. No self-citation chains, ansatz smuggling, or uniqueness theorems from the same authors appear in the derivation. The central upper-limit claim therefore retains independent content from the population synthesis step.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

The central claim depends on an AGN population synthesis model whose parameters are taken from the literature, on the assumption that the lepto-hadronic emission physics calibrated locally applies at all redshifts, and on the fitted wind parameters themselves. No new particles or forces are introduced.

free parameters (1)
  • wind kinetic power and ambient density
    Abstract states these are 'poorly constrained' and are calibrated to the radio/GeV data of nearby Seyferts.
axioms (1)
  • domain assumption Lepto-hadronic emission processes (synchrotron, external-Compton, hadronic) dominate the wind output
    Invoked when constructing the emission model calibrated to Fermi-LAT and radio data.

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