{"id":"9a3eb0cb-8dae-48dc-9f49-428b8950bdce","arxiv_id":"2607.20314","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":5,"one_line_summary":"Viscous angular-momentum transport and jet feedback can keep intermittent accretion disks around newborn neutron stars alive long enough to launch the energetic jet pairs seen in some supernova remnants.","lead":"A single astrophysicist argues that short-lived, randomly oriented accretion disks around newborn neutron stars can survive longer than previously thought, which would let them launch the two or three powerful jet pairs seen in some supernova remnants. The paper is a back-of-the-envelope mechanism study that relies on viscosity and jet feedback, and it explicitly calls for future simulations.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Central claim assumes zero-j infall is captured by the disk; if such gas plunges on a dynamical time, Eqs. (9)-(14) do not apply and the disk lifetime is not prolonged.","rationale":"The reader's weakest assumption correctly identifies the disk-coherence issue, but the deeper problem is not just that the disk may become non-Keplerian: even a coherent Keplerian disk may never capture the zero-j material. Because the infall time for zero-angular-momentum gas is set by free fall, not by viscosity, the gas can transect the disk on a dynamical timescale. The paper's analytical derivation then loses its foundation: the mass-addition term in Eq. (9), the use of M_dot = M_D0/τ_vis, and the angular-momentum balance leading to Eq. (13) all presuppose that the incoming gas is incorporated into the disk and processed viscously. This is a physical assumption, not a mathematical consequence, and the paper provides no evidence for it. I do not think this should change the verdict from CONDITIONAL to REJECT: the paper is explicitly speculative, self-identifies the need for future 3D simulations, and the proposed mechanism may survive once capture is properly modeled. However, the central claim should be regarded as an untested hypothesis. The reader's conditional verdict already captures this, so I recommend no change. Credit is due for the paper's clear caveats and for grounding the observational motivation in a mature, if qualitative, morphological method.","tokens_in":13271,"tokens_out":8405,"duration_ms":88613,"concrete_test":"Run an axisymmetric (or 3D) hydrodynamic simulation with an α-viscosity disk around a 1.4 M⊙ NS, initialized with M_D0, R_out ≈ 60 km, and Σ ∝ r^{-3/4}, and inject gas with zero specific angular momentum at the outer boundary at Ṁ ≈ 0.3 M⊙ s^{-1}, the rate used in Eq. (6). Track disk mass and inner accretion rate over multiple τ_vis. If the disk mass drops below ~e^{-1} M_D0 before Δt ≈ τ_vis, or if the integrated inner accretion of zero-j gas before disk disruption is less than 0.3 M_D0, then the capture assumption behind Eqs. (13)-(14) fails. A cheaper auxiliary check is to compute the ratio of the zero-j free-fall time to τ_vis; if t_ff/τ_vis ≪ 1, the slow viscous-feeding picture is not self-consistent.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Section 3.2 assumes that newly accreted, zero-specific-angular-momentum gas \"adds mass ... to the accretion disk\" and reduces the accretion rate only by k = H/R (Eq. 9). The load-bearing step is the implicit assumption that this gas is captured and then viscously transported inward. A parcel with j = 0 at R ≈ 50 km has no centrifugal support; its dynamical infall time is τ_K ≈ 0.005 s (Eq. 3), an order of magnitude shorter than τ_vis ≈ 0.05 s used in Eq. (14). Such gas will plunge through the disk and onto the NS, or shear against the disk, rather than become part of a Keplerian disk processed on τ_vis. The bookkeeping in Eq. (13) equates the angular momentum lost as (M_D0 + ΔM_D) j_d,j, which presumes that every accreted gram, including the zero-j gas, passes through the inner disk with specific angular momentum j_d,j. But zero-j gas has no angular momentum to lose; it can accrete directly without drawing on the disk's angular momentum reservoir. For the disk to capture it, pressure forces and shocks must transfer angular momentum from the disk to the infalling gas on a timescale that is not derived and is questionable given the paper's own admission (§3.1) that the disk is not relaxed and standard thin-disk models cannot be used. Thus Eqs. (13)-(14) may substantially overestimate both the extra mass ΔM_D and the survival time Δt_D. The headline result Δt_D ≈ τ_vis is close to a dimensional re-statement of the assumed viscous time, and therefore the conclusion that zero-j accretion can be survived depends entirely on the unmodeled capture process.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper, in the framework of the jittering-jets explosion mechanism (JJEM), proposes a mechanism for forming long-lived intermittent accretion disks around newly born neutron stars. The author considers two consecutive accretion episodes: the first with positive specific angular momentum forms a Keplerian-like disk, and the second has zero angular momentum. The central claim is that viscous outward angular momentum transport (Eq. 8) allows the disk to continue accreting zero-angular-momentum gas, with the disk surviving for a time Δt_D ≈ τvis (Eq. 14) and accreting an extra mass ΔM_D ≈ 0.3 M_D0 (Eq. 13). Two additional processes—jet-induced blocking of polar accretion and random angular momentum fluctuations—are argued to further prolong disk lifetime. The paper applies this to explain CCSNRs with two or three energetic jet pairs, such as S147, W44, RCW 89, and G0.9+0.1, thereby strengthening the JJEM as the primary CCSN explosion mechanism.","tokens_in":13766,"tokens_out":5366,"duration_ms":49377,"significance":"If the proposed mechanism is physically valid, it would offer a natural explanation for CCSNRs whose morphology requires two or three jet pairs carrying most of the explosion energy—a feature that is difficult to accommodate within the standard JJEM picture of many short-lived, low-energy jet episodes. The paper is transparent about its assumptions and provides order-of-magnitude estimates that could be tested by future three-dimensional simulations. It also explicitly identifies its speculative nature. However, the quantitative results hinge on a strong and as-yet-unjustified assumption about how zero-angular-momentum gas is captured by the disk, and the headline timescale is essentially the assumed viscous time. Therefore, the significance of the paper is conditional; it is an interesting proposal that currently lacks a firm physical basis for its key bookkeeping step.","major_comments":[{"comment":"The derivation assumes that zero-angular-momentum gas from the second episode is captured by the disk and adds to its mass. This is not self-evident: a parcel with j=0 at R≈50 km has a dynamical infall time τ_K≈0.005 s (Eq. 3), an order of magnitude shorter than τvis≈0.05 s used in Eq. (14). Without centrifugal support, such gas will plunge through the disk on a dynamical time unless pressure gradients or shocks transfer angular momentum to it. The paper does not derive a mechanism or a timescale for this capture, and in §3.1 it admits that the disk is not fully relaxed and the standard thin-disk model cannot be used. Equations (13) and (14) are therefore contingent on an unexamined physical process, and the claimed prolongation may substantially overestimate ΔM_D and Δt_D.","section":"§3.2, Eq. (9)"},{"comment":"The angular momentum reservoir J_D,0 is computed assuming a Keplerian disk with surface density Σ∝r^{-3/4}, a profile characteristic of a steady, optically thick, blackbody-emitting disk. The paper states in §3.1 that such a model cannot be used for these intermittent disks, and indeed acknowledges 'although this is not the case here' before Eq. (11). The factor Q, and hence the numbers in Eqs. (13)–(14), depend on this choice. The author should either provide a physical justification for adopting this profile for a non-relaxed disk or demonstrate that the results are insensitive to the profile.","section":"§3.2, Eq. (11)"},{"comment":"The headline result Δt_D ≈ τvis (Q−1)/0.3 × R/(3H) is dimensionally and substantively a restatement of the assumed viscous timescale τvis. Since τvis is an input parameter (Eq. 1) calibrated to earlier JJEM work, the paper does not predict a new lifetime scale but rather shows that the disk can survive for its own viscous time under certain conditions. The paper should acknowledge this limitation more explicitly; as written, the conclusion that 'the disk can survive for a typical time of the order of its viscous time' is partially circular.","section":"§3.2, Eq. (14)"},{"comment":"Equation (13) equates the angular momentum lost at the inner boundary with (M_D0+ΔM_D)j_d,j. However, the zero-angular-momentum gas in the second episode carries no angular momentum; it cannot lose j_d,j when it reaches the inner disk unless it has been spun up by the disk. The bookkeeping therefore implicitly assumes that all accreted gas, including the zero-j component, acquires the local specific angular momentum before accretion. This is the same capture problem as in the first major comment, but it deserves separate emphasis because it is an internal inconsistency in the angular momentum conservation statement: the newly added mass should not be debited the disk's angular momentum unless it has been entrained.","section":"§3.2, Eq. (13)"}],"minor_comments":[{"comment":"'accretion is continues' should read 'accretion is continuous'.","section":"§3.2, text"},{"comment":"'in he study' is a typo for 'in the study'.","section":"Appendix"},{"comment":"The caption refers to 'red double-lined arrows' and 'dashed-pale-blue arrows', but the figure as rendered appears to have no color or the color coding is unclear. The text should be adjusted to match the actual figure formatting.","section":"Figure 1"},{"comment":"The abbreviations CCSNR and CCSNe are used without full definitions at first occurrence. Considering the broad readership of the journal, the author should define both terms explicitly.","section":"Abstract/Introduction"}],"recommendation":"major_revision","confidential_remarks":"The manuscript is speculative and relies heavily on the author's own prior work, with a substantial fraction of citations being self-citations. This is not necessarily a defect, but the editor may want to consider whether the paper's level of physical justification is sufficient for the journal. The referee's major concerns are about the physical capture of zero-angular-momentum gas and the internal consistency of the angular momentum bookkeeping; these need to be addressed before publication."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Honest, speculative mechanism paper from Soker. The new bit is the angular-momentum bookkeeping: he shows that a disk of mass M_D0 can accrete roughly ΔM_D ≈ 0.3 M_D0 of zero-angular-momentum gas before dying, and that this takes about one viscous time. The algebra in §3.2 checks out, and the idea that outward viscous transport of angular momentum acts as positive feedback for zero-j accretion is a real addition to the JJEM literature. Credit where due: the paper is clearly written about what is assumed, and it repeatedly says the whole thing needs 3D simulations. No fabrication, no hidden circular step beyond what is discussed.\n\nThe soft spot matters. The stress-test note is correct: the model assumes the zero-j gas is captured by the disk and processed on τ_vis, but that gas has no centrifugal support at ~50 km and its dynamical time is ~0.005 s, an order of magnitude shorter than the ~0.05 s viscous time. Nothing in the paper shows the gas actually joins the disk rather than plunging or disrupting it. The paper even admits in §3.1 that the disk is not fully relaxed and that the standard thin-disk model cannot be used, then in §3.2 it uses the standard Σ ∝ r^-3/4 profile to compute the angular momentum reservoir. That's an internal tension, not a fatal contradiction, but it weakens the quantitative result. On top of that, Eq. (14) returns ≈ τ_vis, which was an input. So the 'prediction' is more a consistent framework than a clean falsifiable consequence.\n\nThe observational motivation—two or three energetic jet pairs in some remnants—is qualitative morphology, mostly from the author's own group. Fine for a hypothesis, but it doesn't independently validate the mechanism.\n\nWho this is for: people working on the JJEM or on disk lifetimes around newborn neutron stars. The broader supernova community can treat it as a plausible suggestion needing simulation.\n\nMy recommendation: send to peer review. The calculation is simple enough to check, the author is honest about the speculative status, and a referee can push on the capture assumption (and the use of the standard Σ profile). If that assumption fails, the paper's central claim loses its quantitative footing; if it holds in simulations, this becomes a useful piece of the JJEM picture. I'd want the capture issue addressed before building on it, but it deserves referee time.","headline":"A self-consistent order-of-magnitude argument that zero-angular-momentum accretion can be survived for about one viscous time, but the central capture assumption is unmodeled and the headline timescale is largely the input timescale.","tokens_in":14216,"tokens_out":3353,"would_cite":true,"duration_ms":30864,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"A supernova accretion disk can keep launching jets even after the gas feeding it loses its spin, because viscosity ships angular momentum outward — and this can explain why some supernova remnants show just a few dominant jet pairs.","keywords":["core-collapse supernovae","jittering jets explosion mechanism","intermittent accretion disks","angular momentum transport","viscosity timescale","jet feedback","supernova remnant morphology","neutron star accretion"],"falsifier":"A 3D hydrodynamical simulation of an α-viscosity disk around a neutron star that is suddenly fed gas with zero angular momentum at 0.1–0.3 M⊙/s would settle it: if the disk fragments, becomes strongly non-Keplerian, or accretes in less than one viscous time, then equation (14) overestimates the disk's survival time.","tokens_in":13137,"feed_emoji":"💫","tokens_out":4640,"duration_ms":44765,"temperature":0.7,"pith_summary":"The paper argues that intermittent accretion disks in the jittering-jets explosion mechanism (JJEM) can live much longer than the angular-momentum fluctuations that create them. Specifically, when a disk formed by high-angular-momentum material is subsequently fed gas with zero angular momentum, viscous outward angular-momentum transport lets the disk linger for roughly its own viscous timescale and swallow a few tenths of its own mass before dying. This viscous survival, combined with jet-driven clearing of polar infall and occasional positive-sum angular-momentum fluctuations, can produce the one to three very energetic jet pairs that some supernova remnants show. The result matters because it strengthens the case that jets, not neutrinos, power most core-collapse supernovae.","feed_headline":"Viscosity keeps supernova disks alive to launch energetic jet pairs","feed_subtitle":"A disk fed by gas with no net spin survives about one viscous time, letting 1–3 energetic jet pairs shape the remnant.","key_machinery":"The central object is an intermittent accretion disk around the newly born neutron star, modeled as an α-disk with viscous time τ_vis ≈ 0.01–0.1 s. The key identity is the angular-momentum reservoir factor Q, obtained by integrating the assumed surface density Σ ∝ r^{−3/4} over the disk; Q ≈ 1.3–1.4 measures how much angular momentum the disk stores relative to its inner jet-launching radius. This Q enters the viscous-outward-transport bookkeeping that produces the extra-mass and survival-time estimates, while the jets themselves are assumed to carry away angular momentum from the inner region.","core_discovery":"The author shows with an order-of-magnitude analytic model that an α-disk around a newly born neutron star does not necessarily die when the accreting gas loses its angular momentum. Equations (13) and (14) give the disk's extra accreted mass as ΔM_D ≈ 0.3 M_D0 (Q−1)/0.3 and its survival time as Δt_D ≈ τ_vis (Q−1)/0.3 × R/(3H), so the disk accretes a substantial fraction of its own mass and survives about one viscous time. The mechanism is that viscosity transfers angular momentum outward, while the disk's stored angular momentum reservoir, quantified by the factor Q derived from its surface-density profile, provides the resources to keep accreting zero-angular-momentum gas. These two positi","pith_inferences":["If viscous survival operates similarly in black-hole accretion disks fed by stochastic fallback, it could help explain long-duration gamma-ray bursts that lack a persistent, ordered angular momentum source.","The Q-factor bookkeeping assumes instantaneous mixing of zero-angular-momentum gas; incomplete mixing could create counter-rotating layers that either shorten or lengthen the disk's life, a regime not modeled here.","A testable prediction is that a supernova remnant should rarely show more than three comparably energetic jet pairs; a four-pair case with similar energies would stress the model.","Applying the argument to disks around lower-mass proto-neutron stars (where the inner launching radius and viscous time shift) may predict a mass dependence in the appearance of energetic jet pairs."],"forward_implications":["An intermittent accretion disk can survive the end of the high-angular-momentum episode that formed it, extending jet-launching activity by roughly one viscous time.","Jet-launching episodes can last up to a few tenths of a second and carry a large fraction of the explosion energy, matching the energetic jet pairs inferred in some supernova remnants.","The combination of viscous prolongation, jet-blown bubbles channeling accretion to the equatorial plane, and random angular-momentum fluctuations can produce 1–3 dominant jet pairs rather than many weak ones.","The JJEM can account for supernova remnant morphologies with few, energetic jet axes without requiring rapid pre-collapse core rotation.","The number of dominant jet pairs scales with the viscous time, so variations in disk viscosity or scale height directly affect the observed morphology."],"fun_headline_variants":["Supernova disk viscosity turns zero spin into jet fuel","Long-lived disks from viscosity explain energetic jet pairs","Zero-spin gas still powers jets thanks to disk viscosity","Disk viscosity buys time for supernova jets to fire"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The disk remains a coherent, roughly Keplerian α-disk with a smooth surface-density profile while being fed zero-angular-momentum gas, even though the author admits the disk is not fully relaxed and the standard thin-disk model cannot be applied.","fun_headline_variants_meta":{"raw":{"variants":["Supernova disk viscosity turns zero spin into jet fuel","Long-lived disks from viscosity explain energetic jet pairs","Zero-spin gas still powers jets thanks to disk viscosity","Disk viscosity buys time for supernova jets to fire"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001159,"raw_usage":{"total_tokens":4685,"prompt_tokens":840,"completion_tokens":3845,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":584,"completion_tokens_details":{"reasoning_tokens":3791}},"tokens_in":584,"tokens_out":3845,"duration_ms":23757,"temperature":1.0,"reasoning_tokens":3791,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-01T10:09:59.644614+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A 3D hydrodynamical simulation of an α-viscosity disk around a neutron star that is suddenly fed gas with zero angular momentum at 0.1–0.3 M⊙/s would settle it: if the disk fragments, becomes strongly non-Keplerian, or accretes in less than one viscous time, then equation (14) overestimates the disk's survival time.","supporting_citations":[],"review_version":1}