Beyond Spin: QCD Magnetars

Alberta; Astronomy; Canada); Rachid Ouyed (Department of Physics; University of Calgary

REVIEW 4 major objections 5 minor 13 references

This paper argues that five seemingly unrelated cosmic phenomena—magnetars, superluminous supernovae, luminous fast blue optical transients, and fast radio bursts—are the same engine seen at different stages: the quark-deconfined core of a

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2026-08-01 17:39 UTC pith:YTKS6GAG

load-bearing objection A bold but microphysically unproven unification that deserves referee scrutiny for its concrete predictions, even though the rate fits are partly circular. the 4 major comments →

arxiv 2607.17556 v1 pith:YTKS6GAG submitted 2026-07-20 astro-ph.HE

Beyond Spin: QCD Magnetars

Rachid Ouyed (Department of Physics , Astronomy , University of Calgary , Alberta , Canada) This is my paper

classification astro-ph.HE

keywords neutron starsmagnetarsquark deconfinementhybrid starsferromagnetic quark matterfast radio burstssuperluminous supernovaer-process nucleosynthesis

verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

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

Anomalous X-ray pulsars, soft gamma-ray repeaters, superluminous supernovae, luminous fast blue optical transients, and fast radio bursts are usually treated as five separate phenomena, each needing its own exotic engine. This paper tries to show they are one engine: the "QCD magnetar," a neutron star whose core has deconfined into magnetically ordered up-and-down quark matter. The quark core spontaneously generates a roughly 10^18 gauss magnetic field—set by mass, not birth spin—and the conversion event, a Quark-Nova, ejects the neutron star's crust, powering a kilonova and leaving a bare, crustless star that emits FRBs until a new crust forms and it becomes an AXP/SGR. If right, the same two parameters, a critical mass and a critical spin period, explain the observed rates of all five classes, and make testable predictions: isolated-neutron-star kilonovae, r-process enrichment, and excess dispersion and rotation measure in FRBs. A sympathetic reader would care because the paper offers a route to explaining magnetar-strength fields from dense-matter physics rather than from rare birth spins, and a way to test dense-QCD ordering with astrophysical observations.

Core claim

A neutron star born above a critical mass of roughly 2.1 solar masses has a core density above the quark deconfinement threshold from birth, but the quark bubbles remain pressure-contained until spin-down changes the core pressure at the neutron star's spin-down timescale. Then percolation converts the core to two-flavour quark matter in milliseconds. In that phase, spontaneous ferromagnetism—via mechanisms such as the dual chiral density wave or gluon quantum Hall states—generates a core field of order 10^18 gauss, which maps to a surface field of order 10^15 gauss through a dipole geometry, independent of birth spin. The crust is ejected, so the resulting hybrid star is a crustless QCD mag

What carries the argument

The load-bearing object is the QCD magnetar, a hybrid star produced by a Quark-Nova: a neutron star born above a critical mass whose core deconfines into spontaneously ferromagnetic (u,d) quark matter. The field scale B_QCD of about 10^18 gauss follows from equating magnetic energy density to the QCD energy scale, and the surface field follows from dipole geometry as B_surface ~ B_core (R_core/R_star)^3. The interface between the roughly 10^18 gauss quark core and the roughly 10^15 gauss hadronic envelope stores an estimated 10^48-10^50 erg of magnetic free energy; continued spin-down keeps driving the interface unstable, releasing buoyant flux ropes ("magnetic bubbles") that power the FRB p

Load-bearing premise

Dense (up, down) quark matter at a few times nuclear density must really be spontaneously ferromagnetic; the paper's own appendices concede this is not lattice-verified, the dual chiral density wave is unconfirmed, and higher-loop corrections are uncomputed—if the ground state is not ferromagnetic, there is no 10^18 gauss core field and no engine.

What would settle it

Take a compact object with a precisely measured mass above 2.1 solar masses and a radius and tidal deformability that are consistent with purely hadronic matter. The model's mass threshold M_dec near 2.1 solar masses requires that no such purely hadronic object exist, so a verified example would falsify the mass-threshold logic and, with it, the rate matching for all five transient classes.

Watch this falsifier. Get emailed when new claim-graph text bears on it.

If this is right

Magnetar birth no longer requires millisecond birth spins: the field is a ground-state property of dense quark matter, and the magnetar birth rate is set by the high-mass tail of the neutron-star mass distribution, easing the tension with the observed rarity of fast-spinning newborn pulsars.
Every sufficiently massive neutron star is a QCD magnetar in waiting: it eventually transitions to an AXP/SGR after its crust re-forms, and fast rotators among them produce LFBOTs when the conversion is late, or SLSNe-I when the Quark-Nova is hidden by optically thick supernova ejecta.
Crustless QCD magnetars should act as repeating FRB sources for centuries, with burst activity tied to spin period through polar-cap beaming and reservoir exhaustion; these sources should be X-ray quiet until a crust forms, in contrast to conventional crust-fracture magnetar models.
Quark-Nova ejecta provides a non-merger site for r-process nucleosynthesis and kilonovae from isolated neutron stars, potentially accounting for the Galactic r-process budget and testable through late-time NIR excess and polluted companion stars in LFBOT systems.
FRBs from QCD magnetars should carry an intrinsic, declining dispersion measure and rotation measure from the expanding Quark-Nova ejecta, independent of host and intergalactic contributions, and trackable over decades as the source ages.
If the framework is right, the observed diversity of high-energy transients may be a diversity of disguise rather than origin: future surveys should find transitional objects, such as FRB repeaters that gradually become X-ray loud as a crust forms, or old SLSN remnants that begin emitting FRBs decades after explosion.
The inferred threshold M_dec near 2.1 solar masses turns astrophysical rate measurements into a probe of the dense-QCD phase diagram, discriminating ferromagnetic quark phases that lattice QCD cannot currently reach; this is an editorial extension, not a claim the paper itself makes in those words.
A direct test the paper's logic supports is to measure masses of confirmed AXPs and SGRs: the model implies they should be biased toward the high-mass end of the neutron-star distribution, while rare fossil-field magnetars below M_dec should show no kilonova or r-process signatures.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Desk Editor's Note

A bold but microphysically unproven unification that deserves referee scrutiny for its concrete predictions, even though the rate fits are partly circular.

read the letter

First thing to know: this is a speculative but genuinely bold unification paper. The author has been building the Quark Nova picture for years; what's new here is a two-parameter population synthesis that talks to AXP/SGR, SLSN-I, LFBOT, and FRB rates at once, plus DM/RM predictions for FRBs. The writing is clear and the limitations are honestly stated—its own appendices concede that the main microphysical leg is unproven.

What it does well: it's falsifiable in a useful way. Predictions like mass-biased magnetars, X-ray-quiet FRBs, isolated kilonovae, and DM/RM excess from the QN ejecta are concrete and testable within a decade. The paper is also honest about the deferred MHD work and explicitly disclaims explaining the 16-day periodicity in FRB 180916. That restraint is a real credit.

Soft spots: First, the central premise. B_QCD ~10^18 G rests on spontaneous ferromagnetism in (u,d) quark matter at a few times nuclear density. The paper itself says in Appendices A.3–A.4 that the DCDW phase is a theoretical prediction of NJL-type models, not confirmed by lattice QCD, and that the gluon quantum Hall mechanism is one-loop with higher-loop corrections uncomputed. So the engine's foundation is a model-dependent input, not an established result. If the ground state is not ferromagnetic, the framework collapses.

Second, the rate reproduction is partly circular. Equations (14)–(16) define the AXP/SLSN/LFBOT rates as functions of f_dec and f_fast, then M_dec and P_fast are inferred from those same observed rates. That is a fit, not an independent confirmation. The SNR association is doubly circular: t_SNR = 10^4 yr is calibrated to reproduce 8/30 and then enters the likelihood. The MCMC chain is also short—roughly 26–34 autocorrelation times, against the conventional 50—and no code or data are provided. These don't kill the idea, but they temper the headline claims.

Would I referee it? Yes. The paper deserves serious referee scrutiny because it makes concrete, testable predictions and attempts quantitative comparison. A referee could force an error budget on B_QCD and an independent treatment of t_SNR. My own inclination is skeptical: the central engine is a conjecture, and the quantitative successes are weaker than they look at first pass. For a reader tracking magnetar physics or transient demographics, this is a useful provocation; I wouldn't cite it as support for any specific claim without independent microphysical confirmation.

Referee Report

4 major / 5 minor

Summary. The paper proposes a unified engine for AXPs/SGRs, SLSNe-I, LFBOTs, and FRBs. Neutron stars born above a critical gravitational mass M_dec are posited to have central densities above the quark-deconfinement threshold but to remain metastable hadronic stars until spin-down at t_NS,SpD triggers a Quark-Nova (QN). The deconfined (u,d) core is assumed to be spontaneously ferromagnetic, generating B_QCD ~ 10^18 G and, after dipole reconfiguration, a crustless 'QCD magnetar' with B_HS ~ 10^15 G. Fast rotators (P_0 < P_fast) inject spin-down energy into the QN ejecta, producing LFBOTs or, if the QN occurs before the SN ejecta becomes optically thin, SLSNe-I; slow rotators become AXPs/SGRs after the crust re-forms; the crustless phase powers FRBs through magnetic bubbles at the hadron-quark interface. A population synthesis using log-normal birth distributions and five free parameters finds M_dec ~ 2.1 M_sun and P_fast ~ 5.5 ms and claims agreement with the observed rates of the first three classes. The paper also predicts r-process/kilonova signatures, intrinsic DM and RM from the QN ejecta, a characteristic-age anomaly in SNR-associated magnetars, and hidden FRB repeaters in old SLSNe, and it closes with an unusually candid list of limitations and falsification tests.

Significance. If the core physical premises hold, the framework would unify five transient classes under one mass-selected engine and decouple the origin of magnetar-grade fields from birth spin. The paper's strengths are its concreteness: it gives explicit population-synthesis machinery with MCMC sampling and direct Monte-Carlo classification, and it states numerous falsifiable predictions (mass-biased magnetars, tau_c > t_SNR, secular DM/RM evolution, non-merger r-process/kilonovae, hidden FRB repeaters) that future observations can test. It is also honest about several limitations. However, the entire engine rests on the existence of spontaneous ferromagnetism in (u,d) quark matter at 3-5 rho_nuc, a state the paper itself identifies as unconfirmed; the delayed conversion trigger and the field-transport/FRB mechanism are likewise asserted rather than demonstrated. The paper is therefore best read as a proof-of-principle model with clearly stated observational tests, not as a closed result.

major comments (4)

[§4, Eqs. (14)-(16), Table 3, Figure 2] The claim that the model 'reproduces the observed rates' is overstated and somewhat circular. R_AXP, R_LFBOT, and R_SLSN-I are defined as products of f_dec, f_fast, and f_slsn with R_CCSN, and M_dec and P_fast are then inferred by fitting those same observed rates; the agreement is therefore a fit, not an independent validation. In addition, f_SNR is doubly circular: t_SNR = 10^4 yr is calibrated to reproduce the 8/30 association fraction (Appendix F.2, §4.4) and then enters the likelihood as a constraint. Finally, the LFBOT model value (1.1e-3) in Table 3 actually exceeds the adopted observational upper limit (<1e-3); the abstract's 'reproduces' is too strong and should be softened.
[Appendix A.2-A.4, §2.1] B_QCD ~ 10^18 G is introduced via the dimensional estimate Eq. (A4), not derived from an established ground state. The paper concedes that the DCDW phase is a prediction of NJL-type models, that the gluon quantum-Hall mechanism is one-loop, and that no lattice verification exists at finite baryon density. Since B_QCD sets B_HS, the interface energy reservoir, and the spin-down behavior of all five channels, this is a load-bearing correctness risk. I am not requiring lattice QCD in this paper, but the abstract and conclusions must present the ferromagnetic state as a hypothesis with concrete tests (e.g., the predicted mass-B_HS correlation and the absence of spin-dependence in AXP/SGR fields), not as an established fact.
[§3.1, Appendix A.1, §7.2 item 1] The delayed-trigger premise is asserted without a microphysical calculation. The claim that quark bubbles form at birth but remain with Delta P ≈ 0 until spin-down, then percolate at t_NS,SpD, is not supported by any nucleation model spanning the claimed t_NS,SpD range from days to Myr. Appendix A shows that tau_nuc ranges from microseconds to beyond the Hubble time depending on surface tension and Delta P, but no calculation demonstrates that the metastable state survives until the spin-down pressure threshold for the relevant EOS. The paper itself admits an order-unity uncertainty in t_QN. Because the mapping t_QN = t_NS,SpD controls every classification in §3.3, this needs either a dedicated calculation or an explicit statement that the delay is an assumption, with a sensitivity study showing that the rate predictions are robust to order-unity changes in the delay.
[§2.2, §5, Appendix E, §7.2 items 7 and 9] The sub-second transport of the core field to the surface and the conversion of interface magnetic energy into coherent GHz radio emission are not demonstrated. Parker/Tayler instability growth, flux-rope coherence over the envelope, and the radio-emission efficiency are all deferred to future MHD simulations. These steps carry the entire FRB phenomenology and the X-ray-quiet crustless-phase timescale, so they are load-bearing for the model's central new predictions. The text sometimes presents them as established (e.g., 'the global magnetic-field reconfiguration occurs on a sub-second timescale' in §2.2), which conflicts with the limitations section. The paper should either include idealized MHD estimates or explicitly list these as assumptions and downgrade the corresponding predictions accordingly.

minor comments (5)

[Abstract, §4.1, Table 9] The abstract states 'Two parameters govern the model,' but the MCMC analysis has five free parameters (M_dec, sigma_M, P_fast, sigma_P, sigma_B), plus several fixed inputs. Please rephrase as 'two physically interesting parameters' or similar.
[§4.3, Figure 1] The text claims 'No strong degeneracies are present between M_dec and P_fast' but immediately notes that the broad upper uncertainty in P_fast reflects a genuine degeneracy between P_fast and sigma_P. This is internally inconsistent and should be reconciled.
[§5.3, Eq. (29)] The notation t_wait ~ 0.01 t'_HS,SpD is used, but the text later writes 't_wait ~ 0.01 tau_HS,SpD = 16 days' without defining tau_HS,SpD. Use consistent notation for the HS spin-down timescale.
[Minor typos throughout] Several typographical errors: 'global filed' in §2.2; 'differentiated form' should be 'differentiated from'; 'and and envelope density' in §2.2; 'continuos' in Appendix E; inconsistent capitalization of 'I.e.' These should be corrected in a final pass.
[Figure 2 caption] The caption says 'All five constraints are simultaneously satisfied for the median posterior parameters,' but the LFBOT panel shows the model prediction near or above the upper limit. The caption should acknowledge that the LFBOT constraint is satisfied only marginally or within the adopted penalty width.

Circularity Check

2 steps flagged

SNR-association 'consistency' and the 'centuries' FRB phase are each calibrated to the observed numbers they then claim to reproduce; the rate fit itself is a transparent calibration, not a hidden prediction.

specific steps

self definitional [Section 4.4 / Appendix F.2 (Eq. F36)]
"In the QN framework, a magnetar is associated with a visible SNR only if t_NS,SpD < t_SNR ∼10^4 yrs, i.e. the QN fired before the remnant faded (calibrated to reproduce the observed association fraction; see Appendix F). ... A QCD magnetar is spatially associated with a visible SNR if t_NS,SpD ≲ t_SNR, where we adopt t_SNR = 10^4 yr, calibrated to reproduce the observed association fraction at fiducial parameters"

The threshold t_SNR is chosen specifically to make the model's SNR-association fraction match the observed 8/30 at fiducial parameters, and then the same f_SNR = 8/30 is entered into the likelihood (Eq. F36) as an independent constraint. The reported 'SNR age consistency' (model 0.30 vs observed 0.267) is therefore a tautology: the threshold was constructed to hit that data point. This step cannot independently validate the spin-down-delay picture; it instead imports the observation into the model and then presents the match as support.
self definitional [Section 5.1, Eqs. (19)-(20)]
"We can estimate t'_crust by imposing the P_AXP ∼2–12 seconds period of AXPs and SGRs so that P_AXP ∼2^{1/2}P0 × (1 + t'_crust/t'_HS,SpD)^{1/2}. ... t'_crust ∼32 yr×(P_AXP/s)(10^15 G/B_HS). This suggests the crust forms at t'_crust ∼(64-384) yr; I.e. QCD magnetars act as FRB sources for centuries."

The crust-formation timescale is not derived from independent microphysics; it is obtained by imposing that the model's spin-down evolution reaches the observed AXP/SGR period range (2-12 s). The conclusion that the crustless FRB phase lasts 'centuries' is therefore the assumed input period range converted into a time. The abstract's claim that the HS is 'crustless for centuries' is a restatement of the input, not an independent prediction.

full rationale

The population-synthesis 'reproduction' of R_AXP, R_SLSN, and R_LFBOT (Eqs. 14-16) is a genuine model calibration: M_dec and P_fast are inferred from those same observed rates, and the paper explicitly labels the outcome as a constrained fit and 'posterior predictive' check rather than an out-of-sample prediction. That transparency means the rate fit by itself is not a circularity under the rules here. The two genuine circular steps are ancillary but still load-bearing: (1) t_SNR is explicitly 'calibrated to reproduce the observed association fraction' and the same 8/30 fraction then enters the likelihood, so the SNR-association 'consistency' is built in; (2) t'_crust is derived by imposing the observed 2-12 s AXP period, so 'crustless for centuries' and the associated FRB-phase duration are the input restated. The central microphysical premise (spontaneous ferromagnetism in (u,d) quark matter at ~3-5 ρ_nuc giving B_QCD~10^18 G) is admittedly unverified, but the paper cites external QCD literature and flags the absence of lattice and higher-loop confirmation; that is a correctness risk, not circularity. The framework also offers genuinely independent predictions (e.g., X-ray-quiet FRBs, intrinsic DM/RM excess, high-mass bias of AXPs&SGRs, kilonovae from isolated NSs), which prevents a higher score. The score of 6 reflects the two by-construction 'predictions' while acknowledging the independent content elsewhere.

Axiom & Free-Parameter Ledger

12 free parameters · 10 axioms · 4 invented entities

The central engine rests on a long chain: mass-selected deconfinement -> delayed pressure trigger -> ferromagnetic quark phase -> rapid flux transport -> crustless FRB phase -> crust reformation -> AXP/SGR. The free parameters above are either fitted (M_dec,P_fast, widths) or calibrated (t_SNR) or fixed by fiducial choices (M_QN,R_c/R_NS,B_QCD,B_fossil,c). The axioms are mostly domain assumptions about dense QCD and NS physics; several are explicitly unverified and the paper defers their quantitative support to future MHD.

free parameters (12)

M_dec (deconfinement threshold mass) = 2.05+0.30/-0.32 Msun (posterior median)
Central free parameter; inferred from AXP/SGR, SLSN-I, and LFBOT rate constraints (§4.3).
P_fast (fast/slow rotator threshold) = 5.45+4.86/-3.11 ms (posterior median)
Second central free parameter; constrained mainly by the LFBOT rate; broad posterior (§4.3).
σ_M (birth mass width) = 0.147+0.058/-0.057 dex
Nuisance parameter in the log-normal birth distribution, marginalized over (§4.3).
σ_P (birth period width) = 0.719+0.127/-0.114 dex
Nuisance parameter, marginalized (§4.3).
σ_B (birth field width) = 0.614+0.219/-0.249 dex
Nuisance parameter, marginalized (§4.3).
t_SNR (SNR visibility threshold) = 10^4 yr
Calibrated to reproduce the observed 8/30 AXP-SNR association before being used in the f_SNR likelihood (§4.4, Appendix F.2).
B_fossil,c (double-hump threshold) = 10^14 G
Fixed threshold for double-humped SLSNe; varied over 10^13.5-10^14.5 G with <10% posterior effect (§7.2).
M_QN (ejected mass) = 0.01 Msun
Fiducial from prior QN literature; sets crustless phase and kilonova/FRB timescales (§3.2, Appendix B).
R_c/R_NS (core-to-star radius ratio) = 0.1
Fiducial ratio converting B_QCD to B_HS via dipole scaling; sets the 10^15 G surface field (§2.2).
B_QCD (core field) = ~10^18 G
Dimensional estimate from Λ_QCD≈260 MeV (Eq. A4); not fit, but every observable derives from it.
f_MT (Channel B mass-transfer fraction) = <~10^-2
Bounded by the observed radio-LFBOT rate rather than computed from binary population synthesis (§6.1).
f_rel (relativistic M_QN tail fraction) = unconstrained
Free parameter controlling GRB and orphan X-ray plateau rates from the M_QN distribution tail (§7.3.1).

axioms (10)

domain assumption Ferromagnetic (u,d) quark matter exists at a few times nuclear saturation density and spontaneously magnetizes to ~10^18 G.
Appendix A.2-A.4; based on NJL/DCDW and colour-ferromagnetism models; not lattice verified.
ad hoc to paper A NS born above M_dec has ρ_c>ρ_dec at birth, yet the quark phase remains confined until spin-down drives a pressure threshold at t_NS,SpD.
§3.1, Appendix A.1; no explicit microphysical calculation of ΔP(t).
domain assumption Hadronic maximum mass is below M_dec≈2.1 Msun; hadronic NSs cannot exist above this.
§7.1 falsification #3; PSR J0740+6620 (2.08±0.07) is set aside as recycled.
ad hoc to paper Magnetic flux from the core reaches the surface on sub-second timescales through Parker/Tayler instabilities and establishes a dipole B_HS.
§2.2 and Appendix E; deferred to future MHD.
ad hoc to paper QN ejecta mass M_QN≈0.01 Msun removes the whole crust, leaving the HS crustless for centuries; otherwise AXPs are born crusted.
§3.2, §7.3; distribution of M_QN unconstrained.
ad hoc to paper Rising magnetic bubbles convert a fraction of interface magnetic energy into coherent GHz radio emission.
§5.1; microphysical emission mechanism not specified.
domain assumption QN ejecta is neutron-rich (⟨Y_e⟩~0.03), produces r-process and kilonova with lanthanide opacity.
Appendix C; based on Jaikumar et al. 2007.
ad hoc to paper Birth distributions of M0,P0,B0 are independent log-normals with peaks fixed to the observed radio pulsar population.
§4.1; acknowledged as a simplification.
ad hoc to paper t_QN=t_NS,SpD approximation.
§7.2 limitation 1.
domain assumption Free-free/Sedov-Taylor/shock microphysics for DM/RM screen.
Appendix D.

invented entities (4)

Ferromagnetic (u,d) quark phase in the NS core independent evidence
purpose: Generates the ~10^18 G QCD field that sets the entire magnetar-scale surface field without birth spin
Predicted observables: mass bias in AXPs, X-ray-quiet FRB phase, DM/RM excess; but the phase itself is not independently confirmed.
QCD magnetar (crustless highly magnetized hybrid star) independent evidence
purpose: Central engine linking QN to FRBs and later AXP/SGR behavior
Falsifiable via characteristic age anomaly τ_c>t_SNR, X-ray-quiet FRBs, hidden repeaters in SLSN remnants.
Magnetic bubbles/flux ropes at the hadron-quark interface independent evidence
purpose: Transport magnetic free energy to the surface to power repeating FRBs
Predicted burst clustering/avalanche statistics and no X-ray counterpart during crustless phase; mechanism not directly observed.
QN ejecta as intrinsic DM/RM screen independent evidence
purpose: Produces excess dispersion and rotation measure in FRBs independent of environment
Directly testable via DM/RM excess once Galactic/host/IGM contributions are removed; the paper's Eq. (30)-(31).

pith-pipeline@v1.3.0-alltime-deepseek · 45682 in / 21620 out tokens · 174947 ms · 2026-08-01T17:39:06.657526+00:00 · methodology

0 comments

read the original abstract

We present a unified framework in which anomalous X-ray pulsars (AXPs), soft gamma-ray repeaters (SGRs), superluminous supernovae (SLSNe-I), luminous fast blue optical transients (LFBOTs), and fast radio bursts (FRBs) originate from quark deconfinement in the core of a massive neutron star (NS). Spontaneous ferromagnetism in the deconfined phase generates ~10^18 G core fields, producing a highly magnetized hybrid star (HS) - the "QCD magnetar" - whose surface field is set by NS mass, not birth spin. The Quark-Nova (QN) that forms the HS ejects ~0.01M_sun of neutron-rich outer layers, powering a kilonova and leaving the HS crustless for centuries. During this phase, magnetic instabilities at the hadron-quark interface release rising flux ropes that power X-ray-quiet FRBs; as the crust reforms, the source evolves into an X-ray-loud AXP&SGR. Two parameters govern the model: a critical mass M_dec triggering deconfinement, and a critical period P_fast separating fast and slow rotators. Fast rotators inject spin-down energy into the QN ejecta, producing an LFBOT - directly observable once the SN ejecta is optically thin, or via binary accretion with no preceding SN; otherwise the LFBOT is reprocessed by the SN ejecta into an SLSN-I. A Bayesian Monte Carlo population synthesis reproduces the observed rates of AXPs&SGRs, SLSNe-I, and LFBOTs with M_dec ~2.1M_sun and P_fast ~5.5 ms, and predicts non-merger r-process signatures and kilonovae from isolated NSs, with or without an LFBOT. The QN ejecta also carries its own DM and RM, independent of environment, predicted to appear as excess dispersion and rotation measure in FRBs once Galactic, host, and intergalactic contributions are removed. These provide direct observational tests of the hadron-quark phase transition and ferromagnetic ordering in dense quark matter.

Figures

Figures reproduced from arXiv: 2607.17556 by Alberta, Astronomy, Canada), Rachid Ouyed (Department of Physics, University of Calgary.

**Figure 1.** Figure 1: Joint posterior distribution of the five free parameters (Mdec, σM, Pfast, σP , σB). Diagonal panels show marginalised one-dimensional posteriors; off-diagonal panels show two-dimensional joint posteriors with 1σ (dark regions) and 2σ (light regions) credible contours. Dashed vertical lines mark the 16th, 50th, and 84th percentiles. The broad upper uncertainty in Pfast reflects a genuine degeneracy between… view at source ↗

**Figure 2.** Figure 2: Posterior predictive distributions of the five observational constraints, evaluated from 400 draws from the joint posterior. The bands show the observed ranges or ±1σ intervals from [PITH_FULL_IMAGE:figures/full_fig_p016_2.png] view at source ↗

discussion (0)

Reference graph

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[1958]

magnetic bubbles

analogous to Taylor relaxation (Taylor 1974), ∇ ×B=λB,(E22) whereλis a constant with dimensions of inverse length, fixed by the total magnetic helicity conserved during the relaxation and by the boundary conditions of the relaxing volume; for a relaxed region of characteristic sizeℓ,λ∼2π/ℓ. The dominant instability depends on the local magnetic topology a...

1974
[1988]

that has long been used to interpret magnetar burst statistics. Power-law fluence and duration distributions, together with waiting-time statistics inconsistent with a simple Poisson process, are well established observationally for SGR bursts (Cheng et al. 1996; G¨ o˘ g¨ u¸ s et al. 1999, 2000), and have been interpreted through a two-component core–crus...

1996
[1993]

ΓQ ∼µ 4 q exp − 16πσ 3 3 (∆P)2 µq ,(A2) whereµ q is the quark chemical potential,σis the surface tension of the hadronic-quark interface, and ∆Pis the pressure difference between deconfined quark matter and hadronic matter at the interface. For cold, deleptonised NS cores withT≲1 MeV andµ q ∼300 MeV, both the prefactor (T 4 ≪µ 4 q) and the exponent (large...

1993
[1998]

LKN(t)≈M QN ˙ϵ(t),(C11) with the specific r-process heating rate approximated as (Metzger et al. 2010, and references therein) ˙ϵ(t)≈2×10 10 t 1 day −1.3 erg g −1 s−1 .(C12) We adopt this standard fit as an approximation; the actual heating rate for QN ejecta will differ from NS merger ejecta because the abundance pattern differs, particularly in the acti...

2010
[2003]

2004; Mintz et al

and ∆P≈1–100 MeV fm −3 (Bombaci et al. 2004; Mintz et al. 2010), soτ nuc ranges from microseconds to well beyond the Hubble time depending on the EOS. This large theoretical uncertainty is precisely what makes the astrophysical constraint below valuable. The QN framework provides a specific condition on these parameters. A NS born withM 0 > Mdec has its c...

2004
[2005]

This energy is released primarily as neutrinos on the millisecond timescale of core conversion

andM NS = 2.0M ⊙ is the adopted NS mass. This energy is released primarily as neutrinos on the millisecond timescale of core conversion. The neutrinos deposit energy into the overlying hadronic envelope via charged-current absorption (ν en→pe − and ¯νep→ne +). The mean free path in dense nuclear matter at temperature of a few tens of MeVs isλ env of order...

2005
[2019]

2021); “mod” stands for model

andσ SLSN−I = 0.3 dex (e.g., Frohmaier et al. 2021); “mod” stands for model. This contributes zero penalty when the model rate falls inside the observed range and a Gaussian penalty outside. Upper limits (LFBOT rate; double-humped fraction).—Two of our constraints are reported observationally as one-sided upper limits rather than centered measurements: th...

2021
[2023]

max 0,log 10 Rmod LFBOT −log 10 RUL LFBOT 0.3 #2 ,(F34) withR UL LFBOT = 1×10 −3 (Coppejans et al. 2020; Ho et al. 2023), and lnp DH SLSN−I =− 1 2

and the double-humped SLSN-I fraction (Angus et al. 2019; Chen et al. 2023). Both are implemented as one-sided half-Gaussian penalties above the stated limit, contributing zero penalty when the model prediction falls below it: lnp LFBOT =− 1 2 " max 0,log 10 Rmod LFBOT −log 10 RUL LFBOT 0.3 #2 ,(F34) withR UL LFBOT = 1×10 −3 (Coppejans et al. 2020; Ho et ...

2019

[1] [1]

Supernova Explosions

Acheson, D. J., & Gibbons, M. P. 1978, Philosophical Transactions of the Royal Society of London Series A, 289, 459 Alford, M., & Reddy, S. 2003, PhRvD, 67, 074024 Amiri, M., CHIME/FRB Collaboration, et al. 2021, ApJS, 257, 59 Andersson, N. 1998, ApJ, 502, 708 Angus, C. R., Smith, M., Sullivan, M., et al. 2019, MNRAS, 487, 2215 Annala, E., Gorda, T., Kurk...

Pith/arXiv arXiv 1978

[2] [9]

matched continuously att′ QN,tr: RQN(t) =R tr(t′/t′ QN,tr)2/5, v sh(t) =v QN(t′/t′ QN,tr)−3/5 ,(D18) where the subscript “sh” stands for shock. We get DMQN(t′)∼1.2×10 −2 pc cm−3 × MQN 10−2M⊙ 1/3 namb 1 cm−3 2/3 t′ t′ QN,tr !−4/5 .(D19) D.6.Rotation Measure This depends only on ejecta properties and elapsed timetsince the QN – no ambient medium is required...

1999

[3] [123]

R., Smartt, S

Young, D. R., Smartt, S. J., Valenti, S., et al. 2010, A&A, 512, A70 28Rachid Ouyed Zhang, J.-S., Wang, T.-C., Wang, P., et al. 2025 [arXiv:2507.14707] Zink, B., Lasky, P. D., & Kokkotas, K. D. 2012, PhRvD, 85, 024030 Beyond Spin: QCD Magnetars29 APPENDIX A.QUARK MATTER NUCLEATION AND ORIGIN OF THE QCD FIELD SCALE A.1.Quark nucleation physics The nucleati...

Pith/arXiv arXiv 2010

[4] [575]

2017, MNRAS, 464, 3568 Pursiainen, M., Childress, M., Smith, M., et al

Prajs, S., Sullivan, M., Smith, M., et al. 2017, MNRAS, 464, 3568 Pursiainen, M., Childress, M., Smith, M., et al. 2018, MNRAS, 481, 894 Quimby, R. M., Yuan, F., Akerlof, C., & Wheeler, J. C. 2007a, MNRAS, 431, 912 Quimby, R. M., Wheeler, J. C., H¨ oflich, P., et al. 2007b, ApJL, 668, L99 Quimby, R. M., Kulkarni, S. R., Kasliwal, M. M., et al. 2011, Natur...

2017

[5] [1950]

once swept- up ambient mass equalsM QN. The transition (“tr”) occurs at a radiusR tr = 3MQN 4πmpnamb 1/3 with a corresponding transition timescale t′ QN,tr = Rtr vQN ∼14.5 yr× MQN 10−2M⊙ 1/3 namb 1 cm−3 −1/3 0.1c vQN .(D15) where the ambient densityn amb is set to typical ISM value expected for when the QN occur in isolation in Channel A and Channel B. Be...

1967

[6] [1958]

magnetic bubbles

analogous to Taylor relaxation (Taylor 1974), ∇ ×B=λB,(E22) whereλis a constant with dimensions of inverse length, fixed by the total magnetic helicity conserved during the relaxation and by the boundary conditions of the relaxing volume; for a relaxed region of characteristic sizeℓ,λ∼2π/ℓ. The dominant instability depends on the local magnetic topology a...

1974

[7] [1988]

that has long been used to interpret magnetar burst statistics. Power-law fluence and duration distributions, together with waiting-time statistics inconsistent with a simple Poisson process, are well established observationally for SGR bursts (Cheng et al. 1996; G¨ o˘ g¨ u¸ s et al. 1999, 2000), and have been interpreted through a two-component core–crus...

1996

[8] [1993]

ΓQ ∼µ 4 q exp − 16πσ 3 3 (∆P)2 µq ,(A2) whereµ q is the quark chemical potential,σis the surface tension of the hadronic-quark interface, and ∆Pis the pressure difference between deconfined quark matter and hadronic matter at the interface. For cold, deleptonised NS cores withT≲1 MeV andµ q ∼300 MeV, both the prefactor (T 4 ≪µ 4 q) and the exponent (large...

1993

[9] [1998]

LKN(t)≈M QN ˙ϵ(t),(C11) with the specific r-process heating rate approximated as (Metzger et al. 2010, and references therein) ˙ϵ(t)≈2×10 10 t 1 day −1.3 erg g −1 s−1 .(C12) We adopt this standard fit as an approximation; the actual heating rate for QN ejecta will differ from NS merger ejecta because the abundance pattern differs, particularly in the acti...

2010

[10] [2003]

2004; Mintz et al

and ∆P≈1–100 MeV fm −3 (Bombaci et al. 2004; Mintz et al. 2010), soτ nuc ranges from microseconds to well beyond the Hubble time depending on the EOS. This large theoretical uncertainty is precisely what makes the astrophysical constraint below valuable. The QN framework provides a specific condition on these parameters. A NS born withM 0 > Mdec has its c...

2004

[11] [2005]

This energy is released primarily as neutrinos on the millisecond timescale of core conversion

andM NS = 2.0M ⊙ is the adopted NS mass. This energy is released primarily as neutrinos on the millisecond timescale of core conversion. The neutrinos deposit energy into the overlying hadronic envelope via charged-current absorption (ν en→pe − and ¯νep→ne +). The mean free path in dense nuclear matter at temperature of a few tens of MeVs isλ env of order...

2005

[12] [2019]

2021); “mod” stands for model

andσ SLSN−I = 0.3 dex (e.g., Frohmaier et al. 2021); “mod” stands for model. This contributes zero penalty when the model rate falls inside the observed range and a Gaussian penalty outside. Upper limits (LFBOT rate; double-humped fraction).—Two of our constraints are reported observationally as one-sided upper limits rather than centered measurements: th...

2021

[13] [2023]

max 0,log 10 Rmod LFBOT −log 10 RUL LFBOT 0.3 #2 ,(F34) withR UL LFBOT = 1×10 −3 (Coppejans et al. 2020; Ho et al. 2023), and lnp DH SLSN−I =− 1 2

and the double-humped SLSN-I fraction (Angus et al. 2019; Chen et al. 2023). Both are implemented as one-sided half-Gaussian penalties above the stated limit, contributing zero penalty when the model prediction falls below it: lnp LFBOT =− 1 2 " max 0,log 10 Rmod LFBOT −log 10 RUL LFBOT 0.3 #2 ,(F34) withR UL LFBOT = 1×10 −3 (Coppejans et al. 2020; Ho et ...

2019