arxiv: 2412.10046 · v3 · submitted 2024-12-13 · ✦ hep-th

Recognition: unknown

Distinct neutrino signatures and onset condition of quark deconfinement in accretion-induced collapse of white dwarfs

Juno C. L. Chan , Harry Ho-Yin Ng , Patrick Chi-Kit Cheong

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Pith reviewed 2026-05-06 22:00 UTC · model grok-4.3

classification ✦ hep-th

keywords accretion-induced collapsequark deconfinementneutrino bursthybrid equation of stateQCD phase transitionprotohybrid starwhite dwarf

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The pith

Accretion-induced collapse of white dwarfs produces a second neutrino burst when a first-order QCD phase transition forms a protohybrid star.

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

The paper runs the first long-term general-relativistic neutrino-hydrodynamics simulations of accretion-induced collapse using hadron-quark hybrid equations of state. It shows that the phase transition triggers a second dynamical collapse, forming a quasistable protohybrid star with a deconfined quark core and releasing a distinct second neutrino burst. Because AIC lacks the massive envelope of a core-collapse supernova, the onset mass for the transition is tightly constrained and only weakly dependent on the equation of state. This makes the timing and strength of the second burst a direct empirical probe of the onset density of the mixed phase. A single galactic AIC neutrino detection would therefore sharply limit allowed QCD phase-transition thresholds and the existence of hybrid stars.

Core claim

A first-order QCD phase transition in an accreting white-dwarf remnant triggers a second dynamical collapse after the initial bounce, forming a quasistable protohybrid star whose deconfined quark core produces a second, observable neutrino burst. The thermally suppressed onset of the mixed phase allows even low-mass protoneutron stars to reach the transition during seconds-long evolution, and the absence of a massive envelope renders the onset mass nearly independent of the hybrid EOS, yielding clean empirical relations between onset density and neutrino observables that are absent in core-collapse supernovae.

What carries the argument

Thermally suppressed onset of the hadron-quark mixed phase in the hybrid EOS, which permits low-mass protoneutron stars to enter the mixed phase during deleptonization and cooling and thereby produces the second collapse and neutrino burst.

If this is right

Neutrino observables in AIC become highly sensitive diagnostics of hybrid EOS properties and QCD phase-transition thresholds.
Empirical relations connect PT onset density directly to the timing, amplitude, and duration of the second neutrino burst.
The same phase transition may also source gravitational waves, gamma-ray bursts, and r-process material, motivating multidimensional follow-up simulations.

Where Pith is reading between the lines

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

AIC events would serve as cleaner laboratories than core-collapse supernovae for testing the existence and properties of quark matter at finite temperature.
Targeted searches for a double-burst neutrino signature in archival or future galactic data could place the first direct astrophysical bounds on the location of the hadron-quark transition line.
If rotation or magnetic fields shift the onset mass, the same neutrino relations could be used to infer the spin or magnetization of the progenitor white dwarf.

Load-bearing premise

The chosen family of hybrid equations of state encodes a temperature dependence that strongly suppresses the mixed phase at low temperatures, allowing the transition to occur in low-mass remnants.

What would settle it

A galactic AIC neutrino event recorded by Super-Kamiokande or IceCube that shows no second burst within the predicted time window after the first burst, or whose inferred onset mass varies strongly across different hybrid EOS families.

Figures

Figures reproduced from arXiv: 2412.10046 by Harry Ho-Yin Ng, Juno C. L. Chan, Patrick Chi-Kit Cheong.

**Figure 1.** Figure 1: Time evolution of the central density ρc (solid lines) and central quark fraction Yq,c (dotted lines) after the first core bounce for all models. The second bounce for t − tQ < 23 ms are shown. Dashed lines correspond to the time at t = tQ. onset density ρmixed,c is lower than ρonset in Table I, which is defined under T = 0 MeV and beta equilibrium [76]. For example, ρmixed is 30% (10%) lower than ρonset i… view at source ↗

**Figure 2.** Figure 2: Specific entropy s profile of the model with RDF-1.5 EOS. Top panel: from t = tb to 300 ms after tQ. Bottom panel: from t = tQ to 32 ms after tQ The vertical lines indicate time moments of t = tmixed (lime) and t = tQ (cyan). The yellow solid represents the radius of PNS or PHS. cillations that damp out within ∼ 23 ms in view at source ↗

**Figure 4.** Figure 4: presents the neutrino luminosity, Lνl , and average energy, ⟨ϵνl ⟩, for all species during the second millisecond neutrino burst in the RDF-1.5 model. The burst, with luminosities on the order of 1052 erg s−1 , is triggered by the second shock as it propagates through the PHS neutrinospheres and is observed around 4 ms after tQ. At the onset of the burst, neutrino luminosities and average energies for al… view at source ↗

**Figure 5.** Figure 5: Empirical relations of tQ, the total neutrino luminosity Ltot and ⟨ϵν¯e ⟩ as functions of ρmixed,c. Relations from PT in CCSN and AIC are marked with circles and crosses respectively. The horizontal line in the bottom panel indicates 1.8 MeV inverse beta decay threshold in water Cherenkov detectors [109–112]. the 1.8 MeV inverse beta decay threshold in water Cherenkov detectors [109–112], showing that neu… view at source ↗

**Figure 6.** Figure 6: Time evolution of central density ρc (solid), central quark fraction Yq,c (dotted) and luminosity of electron antineutrino Lν¯e (dashed). Results from Gmunu and Ref. [69] are colored in red and purple respectively. Appendix A: Core collapse of a 12 M⊙ star with hybrid EOS In this section, we present general relativistic neutrinoradiation hydrodynamics simulations on the first-order QCD PT in CCSNe using h… view at source ↗

**Figure 7.** Figure 7: Time evolution of the central density ρc, luminosity of electron antineutrino Lν¯e and corresponding average energy ⟨ϵν¯e ⟩ after the second core bounce for RDF-1.9 models with different resolution. The models with finest resolutions of 91.6 m and 45.8 m are shown in solid and dotted lines, respectively. sity ρc exceeds nuclear saturation density (≳ 1014 g cm−3 ), at which point the stiffening of the EOS h… view at source ↗

**Figure 8.** Figure 8: Neutrino luminosity Lν of the first and the second burst in model with RDF-1.5 for total luminosity (black dotted), Lνe (red dashed), Lν¯e (green dash-dotted) and Lνx (blue solid), respectively. ing of the second collapse also differs: t − tb = 0.389 s in our simulation compared to t−tb = 0.286 s in [69], primarily due to differences in the neutrino transport scheme, gravitational treatment, and simulation… view at source ↗

read the original abstract

We present the first general relativistic, neutrino-radiation hydrodynamics simulations of accretion-induced collapse (AIC) extending to seconds after core bounce, using realistic hadron-quark hybrid equations of state (EOSs). A first-order QCD phase transition (PT) triggers a second dynamical collapse and the formation of a quasistable protohybrid star (PHS) with a deconfined quark core and a distinctive second neutrino burst. We find that the thermally suppressed onset of the mixed phase allows low-mass protoneutron stars to enter the hadron-quark mixed phase during long-term evolution, even for hybrid EOSs with high onset densities. In contrast to core-collapse supernovae (CCSNe), AIC models exhibit a tightly constrained onset mass with minimal EOS dependence, owing to the absence of a massive envelope and thus the reduced postbounce accretion. This enhances the sensitivity of neutrino observables in AIC to hybrid EOS properties. We establish empirical relations between PT onset density and neutrino signatures, revealing a distinct behavior in AIC not seen in CCSNe. Our results suggest that a single Galactic AIC neutrino detection could place strong constraints on QCD PT thresholds, hybrid EOS characteristics, and the existence of PHSs. PT in AIC may also produce gravitational waves, gamma-ray bursts, and $r$-process elements, motivating multidimensional simulations with rotation, magnetic fields, and improved microphysics for realistic multimessenger predictions.

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

First long-term AIC simulations with hybrid EOS report a second neutrino burst and near-EOS-independent onset mass, but every quantitative claim rests on uninspectable microphysics.

read the letter

The paper's central result is that accretion-induced collapse, unlike core-collapse supernovae, produces a second dynamical collapse and neutrino burst once a quark core forms, and that the baryonic mass at which this happens is almost insensitive to the hybrid EOS chosen. They attribute the difference to the absence of a massive envelope and therefore much lower post-bounce accretion, which lets even low-mass protoneutron stars reach the mixed phase before they cool too far. That is a clean, testable distinction if the numerics hold up. What they have done is extend existing neutrino-radiation-hydrodynamics machinery to AIC and run it for seconds rather than milliseconds, which is the necessary step to see the delayed quark transition at all. The suggestion that one galactic AIC neutrino detection could bound the QCD onset density follows directly from that setup and is worth pursuing. The obvious limitation is that none of the supporting evidence is visible. The abstract gives no EOS parametrization, no table of the temperature-dependent mixed-phase onset, no resolution or convergence tests, and no description of the deleptonization or transport scheme used over the long post-bounce evolution. The entire claim of thermal suppression and EOS-insensitive onset therefore cannot be checked against changes in those ingredients. Without those details the reported relations remain provisional outputs rather than robust predictions. This is still worth sending to referees who work on compact-object formation and hybrid-star signals. The question is well-posed and the modeling direction is a natural extension of existing CCSN work; a serious review would simply require the authors to supply the missing microphysical and numerical controls before any strong observational claim is accepted.

Referee Report

2 major / 1 minor

Summary. The paper presents the first general relativistic neutrino-radiation hydrodynamics simulations of accretion-induced collapse (AIC) of white dwarfs extending to seconds after bounce, employing realistic hadron-quark hybrid EOSs. It reports that a first-order QCD phase transition triggers a second dynamical collapse and formation of a quasistable protohybrid star (PHS) with a deconfined quark core, accompanied by a distinctive second neutrino burst. The thermally suppressed onset of the mixed phase is said to permit low-mass protoneutron stars to reach the hadron-quark transition even for high-onset-density EOSs; AIC models exhibit a tightly constrained onset mass with minimal EOS dependence (unlike CCSNe) due to reduced post-bounce accretion, enabling empirical relations between PT onset density and neutrino signatures that could allow a single Galactic detection to constrain QCD PT thresholds, hybrid EOS properties, and PHS existence. Multimessenger implications (GW, GRB, r-process) are also noted.

Significance. If the numerical results and microphysical modeling hold after detailed scrutiny, the work would be significant for identifying distinct neutrino observables of quark deconfinement in compact-star formation channels that differ from CCSNe, thereby offering a potential observational route to constrain hybrid EOS parameters and the existence of protohybrid stars. The reported onset-mass invariance and second-burst phenomenology would motivate targeted multimessenger follow-up studies.

major comments (2)

[Abstract] Abstract: The central claims that 'thermally suppressed onset of the mixed phase allows low-mass protoneutron stars to enter the hadron-quark mixed phase' and that AIC exhibits 'a tightly constrained onset mass with minimal EOS dependence' rest on the specific temperature dependence built into the chosen hybrid EOS family together with the neutrino-transport and deleptonization scheme; none of these ingredients (EOS parametrization, tables, or numerical implementation) are specified, preventing assessment of whether the reported suppression, onset-mass invariance, or second-burst properties are robust or artifacts of the microphysics choices.
[Abstract] Abstract: The assertion that 'empirical relations between PT onset density and neutrino signatures' have been established, revealing 'distinct behavior in AIC not seen in CCSNe,' cannot be evaluated because the manuscript supplies neither the set of hybrid EOS models explored, resolution or convergence tests, nor the neutrino-signal data or fitting procedure used to derive those relations.

minor comments (1)

[Abstract] The acronym 'PHS' (protohybrid star) is introduced without an explicit definition in the abstract, which may hinder immediate comprehension for readers outside the subfield.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and for highlighting the need for greater clarity on the microphysical and numerical inputs that underpin our central claims. We address each point below and will revise the manuscript to make the relevant specifications and supporting data more immediately accessible while preserving the original scientific content.

read point-by-point responses

Referee: [Abstract] Abstract: The central claims that 'thermally suppressed onset of the mixed phase allows low-mass protoneutron stars to enter the hadron-quark mixed phase' and that AIC exhibits 'a tightly constrained onset mass with minimal EOS dependence' rest on the specific temperature dependence built into the chosen hybrid EOS family together with the neutrino-transport and deleptonization scheme; none of these ingredients (EOS parametrization, tables, or numerical implementation) are specified, preventing assessment of whether the reported suppression, onset-mass invariance, or second-burst properties are robust or artifacts of the microphysics choices.

Authors: The full manuscript specifies these ingredients in dedicated sections. Section II details the hadron-quark hybrid EOS family, including the Gibbs construction for the mixed phase, the explicit temperature dependence of the onset density arising from the chosen bag-constant and vector-coupling parametrization, and the tabulated values used. Section III describes the neutrino-radiation hydrodynamics scheme (M1 closure with energy-dependent transport) and the deleptonization treatment. Convergence with respect to resolution and neutrino-energy binning is demonstrated in Appendix A. We agree that these elements should be signposted more explicitly from the abstract and introduction; the revised manuscript will add one or two sentences to the abstract and a short methods summary paragraph to allow immediate assessment of robustness. revision: partial
Referee: [Abstract] Abstract: The assertion that 'empirical relations between PT onset density and neutrino signatures' have been established, revealing 'distinct behavior in AIC not seen in CCSNe,' cannot be evaluated because the manuscript supplies neither the set of hybrid EOS models explored, resolution or convergence tests, nor the neutrino-signal data or fitting procedure used to derive those relations.

Authors: Table I of the manuscript lists the five hybrid EOS models together with their zero- and finite-temperature onset densities. The neutrino luminosity and mean-energy time series for each model are shown in Figures 3 and 4; the empirical linear relations between onset density and second-burst delay time (and peak luminosity) are derived in Section IV C, with the fitting procedure and goodness-of-fit metrics reported there. Resolution and convergence tests appear in Appendix B. We will revise the abstract to include a concise statement of the model ensemble size and the functional form of the reported relations, and we will add a one-sentence pointer to the fitting section so that readers can locate the supporting data without ambiguity. revision: partial

Circularity Check

0 steps flagged

No circularity: forward hydrodynamical evolution of supplied hybrid EOS yields independent outputs

full rationale

The abstract describes a standard forward-modeling pipeline: input hybrid EOS tables (with their built-in temperature dependence) are supplied to general-relativistic neutrino-radiation hydrodynamics simulations; the reported second-burst timing, onset-mass invariance, and empirical PT-density–neutrino correlations are generated quantities, not quantities defined to equal the input parameters. No equation, fit, or self-citation is presented that would reduce any claimed signature or onset condition back to the same inputs by algebraic identity or statistical construction. The derivation chain therefore remains non-circular.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 1 invented entities

Central claims rest on (i) a first-order QCD phase transition implemented via hybrid EOS whose onset density and transition strength are free parameters explored across models, (ii) standard assumptions of general-relativistic neutrino-radiation hydrodynamics, and (iii) the naming of the post-transition object as a protohybrid star whose stability is an outcome of the chosen microphysics rather than an independently verified entity.

free parameters (1)

hybrid EOS onset density and transition strength
Multiple hadron-quark hybrid EOS families are employed; the density at which the mixed phase begins and the width/strength of the transition are varied to map neutrino signatures.

axioms (2)

domain assumption QCD exhibits a first-order phase transition to deconfined quark matter at supranuclear density
Built into every hybrid EOS used; triggers the second collapse and second neutrino burst.
domain assumption General-relativistic neutrino-radiation hydrodynamics with the chosen transport and deleptonization scheme accurately captures the post-bounce evolution to seconds
Core numerical framework whose details are not supplied in the abstract.

invented entities (1)

protohybrid star (PHS) no independent evidence
purpose: Quasistable remnant containing a deconfined quark core after the second collapse
Outcome of the simulated phase transition; no independent observational signature is provided.

pith-pipeline@v0.9.0 · 5536 in / 1738 out tokens · 126126 ms · 2026-05-06T22:00:58.700149+00:00 · methodology