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arxiv: 2604.25084 · v1 · submitted 2026-04-28 · 🌌 astro-ph.HE

Recognition: unknown

Non-Monotonic Rotation Imprint on Time-Integrated Neutrino Spectral Moments in a 15\,M_odot Core-Collapse Supernova Sequence

Nicolas Viaux

Authors on Pith no claims yet

Pith reviewed 2026-05-07 15:34 UTC · model grok-4.3

classification 🌌 astro-ph.HE
keywords core-collapse supernovaneutrino spectral momentsrotation imprintspectral shift planeaccretion phasenon-monotonic responseGarching modelsneutrino pinching parameter
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The pith

In one core-collapse supernova model sequence, slow rotation hardens neutrino spectra while fast rotation softens them, placing the cases in opposite quadrants of a spectral shift plane.

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

The paper reanalyzes three published three-dimensional simulations of a 15 solar mass star collapsing to form a supernova: one non-rotating, one with slow initial rotation, and one with artificially boosted fast rotation. It shows that the time-integrated neutrino spectral moments shift in opposite directions for the slow and fast cases relative to the non-rotating baseline, with fast rotation producing softer and more pinched spectra and slow rotation producing the reverse but weaker effect. A reader would care because these moments encode information about the collapsing core that could be measured in a galactic supernova neutrino detection, yet the non-monotonic response means rotation cannot be read off as a simple monotonic trend. The analysis isolates the early post-bounce accretion phase where the imprint is strongest and demonstrates that the pattern holds across every line of sight.

Core claim

For this specific model sequence, SR and FR shift the integrated spectral moments in opposite directions relative to NR: FR drives the spectra toward softer, more-pinched states, while SR moves them weakly toward harder, less-pinched states. Placed in a spectral-shift plane (Δ⟨E⟩_L, Δα_L), NR sits at the origin, and SR and FR occupy diagonally opposite quadrants, making the non-monotonic response immediately visible as an anti-correlation in two spectral dimensions simultaneously.

What carries the argument

The spectral-shift plane whose axes are the change in mean neutrino energy (Δ⟨E⟩_L) and the change in pinching parameter (Δα_L), which together map how rotation alters the time-integrated neutrino spectra during accretion.

If this is right

  • The fast-rotation signature remains coherent across all 15488 lines of sight.
  • The opposite shifts are established during the early accretion interval from 0.05 to 0.30 seconds after bounce.
  • Fast rotation produces quantitative shifts of order -0.5 MeV in mean energy and +0.16 in pinching for electron neutrinos and antineutrinos.
  • With only three models the result is a phenomenological characterization of one published sequence rather than a general functional dependence on rotation rate.

Where Pith is reading between the lines

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

  • The non-monotonic pattern hints that the response to rotation rate may be nonlinear, so additional models at intermediate rates would be needed to trace the curve.
  • If the same diagonal separation appears in other progenitors, it would complicate using neutrino mean energy and pinching as direct diagnostics of core angular momentum.
  • Re-examining existing supernova simulation outputs with this two-dimensional shift diagnostic could reveal rotation imprints that single-moment analyses miss.

Load-bearing premise

The observed opposite shifts arise purely from the imposed rotation rates rather than from other differences in the three published models or from the specific numerical setup of the Garching sequence.

What would settle it

A new simulation at an intermediate rotation rate between 0.5 and 150 rad/s that produces spectral shifts lying on the line connecting the slow and fast cases would falsify the non-monotonic claim for this sequence.

Figures

Figures reproduced from arXiv: 2604.25084 by Nicolas Viaux.

Figure 1
Figure 1. Figure 1: Central result: non-monotonic, opposite-direction spectral response to rotation, integrated over tpb = 0.05–0.30 s. (a) Fractional shifts δ⟨Eν¯e ⟩L (orange-red circles, Eq. 3) and δαν¯e,L (blue squares) plotted along the rotation sequence NR→SR→FR. The two curves open as a scissors: SR moves slightly in one direction while FR moves strongly in the opposite direction in both spectral dimensions simultaneous… view at source ↗
Figure 2
Figure 2. Figure 2: All-sky-averaged time evolution of the ν¯e signal for the three Garching models. (a) Luminosity Lν¯e (t). (b) Mean energy ⟨Eν¯e ⟩(t). (c) Pinch parameter αν¯e (t). Colors: NR = black solid, SR = orange dashed, FR = magenta dash-dot. The shaded strip marks the integration window 0.05–0.30 s. The spectral quanti￾ties (b) and (c) show a clear and persistent separation between FR and the NR/SR pair, while the … view at source ↗
Figure 3
Figure 3. Figure 3: Integrated response of the rotating sequence. (a) Fractional shifts of positive observables relative to NR for both SR (orange) and FR (magenta). The largest shifts are in the spectral channels; luminosity and calorimetric observables respond more weakly. (b) Absolute values and model differences for the flavor-hierarchy gaps ∆Eν¯e−νe , ∆Eνx−νe , ∆Eνx−ν¯e , and the normalized electron-lepton-number excess.… view at source ↗
Figure 4
Figure 4. Figure 4: Mollweide projection sky maps of the temporal standard deviation of the ν¯e spectral observables for the Garching 15 M⊙ sequence, computed over tpb = 0.05–0.30 s across all 15 488 lines of sight. Left column: NR baseline maps of σ[⟨Eν¯e ⟩ LOS L (t)] (top, plasma scale) and σ[α LOS ν¯e,L(t)] (bottom, viridis scale). Spherical-harmonic decomposition (see text) shows these maps are isotropic at ℓ ≤ 2; the app… view at source ↗
read the original abstract

We study the early post-bounce neutrino signal of the published Garching $15\,M_\odot$ rotating core-collapse supernova (CCSN) sequence consisting of non-rotating (NR), slowly rotating (SR, $\Omega_0=0.5$ rad\,s$^{-1}$), and fast-rotating (FR, $\Omega_0=150$ rad\,s$^{-1}$, artificially boosted ${\sim}300{\times}$) three-dimensional models. We present a new analysis of these publicly available simulation data; no new simulations were performed. Our central result, for this specific model sequence, is that SR and FR shift the integrated spectral moments in \emph{opposite directions} relative to NR: FR drives the spectra toward softer, more-pinched states, while SR moves them weakly toward harder, less-pinched states. Placed in a spectral-shift plane $(\Delta\langle E\rangle_L,\,\Delta\alpha_L)$, NR sits at the origin, and SR and FR occupy \emph{diagonally opposite quadrants}, making the non-monotonic response immediately visible as an anti-correlation in two spectral dimensions simultaneously. The focus is the accretion interval $t_{\rm pb}=0.05$--$0.30$\,s, where the rotation imprint is strongest. Quantitatively, fast rotation produces $\Delta\langle E_{\nu_e}\rangle_L=-0.513$\,MeV and $\Delta\alpha_{\nu_e}=+0.161$, with corresponding shifts $\Delta\langle E_{\bar\nu_e}\rangle_L=-0.440$\,MeV and $\Delta\alpha_{\bar\nu_e}=+0.173$; the SR shifts are an order of magnitude smaller and in the opposite sense. The fast-rotation signature is coherent across all $15\,488$ lines of sight and is established during early accretion. With only three models from a single progenitor family, this result is a phenomenological characterization of one published sequence and a suggestive indication of a non-monotonic, possibly strongly nonlinear, rotational response within this sequence; the functional form and generality of the dependence on $\Omega_0$ remain unconstrained.

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 / 2 minor

Summary. The manuscript performs a post-processing analysis of publicly available 3D CCSN simulation outputs for a 15 M⊙ Garching sequence consisting of non-rotating (NR), slowly rotating (SR, Ω₀=0.5 rad s⁻¹), and fast-rotating (FR, Ω₀=150 rad s⁻¹, artificially boosted ~300×) models. Focusing on the accretion phase t_pb=0.05–0.30 s, it reports that SR and FR produce shifts in the time-integrated luminosity-weighted spectral moments (⟨E⟩_L and α_L) that are opposite in sign relative to NR: FR drives spectra softer and more pinched (e.g., Δ⟨E_νe⟩_L = −0.513 MeV, Δα_νe = +0.161), while SR produces weaker shifts in the opposite direction. These place SR and FR in diagonally opposite quadrants of the (Δ⟨E⟩_L, Δα_L) plane, with the signature coherent across all 15,488 lines of sight. The result is presented as a phenomenological characterization of this specific sequence.

Significance. If the reported anti-correlated shifts hold, the work provides a concrete, quantitative indication of non-monotonic rotational dependence in neutrino spectral moments for this model family, which could inform interpretation of future CCSN neutrino detections. A clear strength is the parameter-free, direct computation of moments from existing simulation data with no additional fitting or invented entities. The coherence statement across thousands of sightlines adds robustness within the sequence. However, the restriction to three models from one progenitor family and the artificial boost in the FR case limit the result's generality and make it suggestive rather than definitive.

major comments (2)
  1. [§2 and abstract] §2 (model description) and abstract: The central claim that the opposite shifts in (Δ⟨E⟩_L, Δα_L) arise from the imposed Ω₀ values alone is load-bearing. The FR model uses an artificial ~300× boost relative to SR, and the three models belong to one published sequence. Without an explicit side-by-side verification (e.g., table or text) confirming that initial conditions, grid resolution, microphysics, and numerical methods are identical except for rotation, uncontrolled differences could contribute to the observed shifts. The paper correctly labels the result phenomenological, but this assumption requires direct support to isolate the rotation effect.
  2. [§4] §4 (results on spectral shifts): The non-monotonic signature is quantified with specific numbers (e.g., Δ⟨E_νe⟩_L = −0.513 MeV for FR), but the manuscript does not report the variance or distribution of these shifts across the 15,488 lines of sight. Stating coherence is useful, yet showing the standard deviation or a histogram of per-sightline Δ⟨E⟩_L and Δα_L would test whether the quadrant placement is uniform or driven by outliers, directly affecting the strength of the anti-correlation claim.
minor comments (2)
  1. [abstract and §3] The subscript L (luminosity-weighted) and the exact definition of the pinching parameter α are used throughout but should be restated briefly in the abstract or first results section for readers who encounter the paper independently.
  2. [results figures] Figure showing the spectral-shift plane would benefit from explicit error bars or a scatter overlay to visualize the claimed coherence across sightlines rather than relying solely on the statement of uniformity.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive comments. We address the two major comments point by point below, agreeing that targeted revisions will strengthen the manuscript while preserving its phenomenological scope.

read point-by-point responses

  1. Referee: [§2 and abstract] §2 (model description) and abstract: The central claim that the opposite shifts in (Δ⟨E⟩_L, Δα_L) arise from the imposed Ω₀ values alone is load-bearing. The FR model uses an artificial ~300× boost relative to SR, and the three models belong to one published sequence. Without an explicit side-by-side verification (e.g., table or text) confirming that initial conditions, grid resolution, microphysics, and numerical methods are identical except for rotation, uncontrolled differences could contribute to the observed shifts. The paper correctly labels the result phenomenological, but this assumption requires direct support to isolate the rotation effect.

    Authors: We agree that explicit verification is needed to isolate the rotation effect as cleanly as possible. The three models belong to the same publicly released Garching 15 M⊙ sequence, whose source papers (cited in our §2) state that the numerical setup, grid, microphysics, and neutrino transport are identical, with the sole controlled difference being the initial rotation rate Ω₀ (explicitly noted as artificially boosted by ~300× in the FR case). To make this transparent, we will insert a short table in §2 that lists the shared parameters alongside the differing Ω₀ values and provides direct references to the original simulation descriptions. This addition supports the phenomenological framing without claiming broader generality. revision: yes

  2. Referee: [§4] §4 (results on spectral shifts): The non-monotonic signature is quantified with specific numbers (e.g., Δ⟨E_νe⟩_L = −0.513 MeV for FR), but the manuscript does not report the variance or distribution of these shifts across the 15,488 lines of sight. Stating coherence is useful, yet showing the standard deviation or a histogram of per-sightline Δ⟨E⟩_L and Δα_L would test whether the quadrant placement is uniform or driven by outliers, directly affecting the strength of the anti-correlation claim.

    Authors: We agree that quantifying the distribution strengthens the coherence statement. Because our analysis post-processes the moments on a per-sightline basis, the full set of 15,488 values is available. In the revised §4 we will report the standard deviations of Δ⟨E⟩_L and Δα_L for both the SR and FR cases relative to NR, and we will add a compact inset histogram (or brief statistical summary) showing that the quadrant placement is uniform across sightlines rather than driven by outliers. This directly addresses the robustness of the reported anti-correlation. revision: yes

Circularity Check

0 steps flagged

No circularity: direct post-processing of existing simulation data

full rationale

The paper's analysis consists solely of computing time-integrated spectral moments (⟨E⟩_L and α_L) from publicly available Garching simulation outputs for the NR, SR, and FR models over t_pb = 0.05–0.30 s. No new simulations are run, no parameters are fitted, no equations are derived or solved, and no self-citations or ansatzes are invoked to generate the reported shifts. The central result—that SR and FR produce opposite displacements in the (Δ⟨E⟩_L, Δα_L) plane—is obtained by straightforward averaging and differencing of the simulation data. All load-bearing steps are external to the paper (the input simulation snapshots) and reduce to direct numerical post-processing rather than any self-referential construction.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The claim rests on the accuracy of the three existing Garching 3D simulations and on the post-processing procedure used to extract time-integrated spectral moments; no new free parameters, axioms, or entities are introduced by this re-analysis.

axioms (1)
  • domain assumption The published Garching 3D CCSN simulations accurately capture the neutrino emission physics for the chosen rotating progenitors.
    The paper performs no new simulations and therefore inherits all assumptions and numerical choices of the original models.

pith-pipeline@v0.9.0 · 5705 in / 1483 out tokens · 66334 ms · 2026-05-07T15:34:18.493298+00:00 · methodology

discussion (0)

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