{"id":"ec9ce1f7-3221-49c4-899b-773879233ae3","arxiv_id":"2508.21042","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":7.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":8,"one_line_summary":"A population synthesis with detailed binary grids shows stripped-envelope supernovae mostly come from primary stars stripped by stable mass transfer, with a flat total rate across metallicity but strong subtype variation.","lead":"Using a detailed binary-star population code, the authors modeled how stripped-envelope supernovae form at six metallicities. They find binary mass-transfer dominates, the total rate is nearly metallicity-independent, while the subtype mix changes strongly with metal content.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"CE<6% claim rests on untested stability criteria and an unquantified alpha_CE=5 sensitivity; need CE-fraction breakdown for that run.","rationale":"The reader's weakest assumption correctly identifies CE physics as the key uncertainty. My stress-test sharpens this: the alpha_CE=5 run is not by itself evidence that CE>6%, because it changes only survival after CE, not the stability boundary that determines how many systems enter CE. The more fundamental issue is that no sensitivity run varies the unstable-MT criteria, and the paper does not report the CE fraction for the alpha_CE=5 model. However, the central qualitative claim—stable binary MT dominates SESN formation—is supported by the fiducial model and by the relatively modest changes in subtype counts across most robustness tests. The concern is a condition on how the result is stated and verified, not a demonstrated internal inconsistency. Thus the reader's CONDITIONAL verdict remains appropriate; I would not move it to ACCEPT or REJECT on this basis.","tokens_in":47606,"tokens_out":3447,"duration_ms":40779,"concrete_test":"Using the POSYDON v2 commit 891c5897 and the population-run outputs, recompute the total fraction of SESNe (Ic+Ib+I(I)b+IIb) that undergo a successful CE in (a) the fiducial alpha_CE=1 model and (b) the alpha_CE=5 model, for both solar and 0.1 Zsun. Classify CE-success events exactly as in Table 1's parenthetical percentages. If the alpha_CE=5 CE fraction is still <6% at both metallicities, the abstract's bound is robust to CE efficiency; if it exceeds 6%, the '<6%' statement must be qualified as fiducial-model-dependent and the stability criteria should be revisited.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The abstract's headline 'common-envelope channel contributes less than 6% of SESNe' depends on two linked assumptions: (i) POSYDON's criteria for dynamically unstable mass transfer (§2, 'Common envelope')—Mdot>0.1 Msun/yr, L2 overflow, or photon-trapping radius comparable to the Roche lobe—and (ii) the alpha_CE=1, lambda_CE-from-MESA prescription for CE survival. The stability criteria are not varied in any sensitivity run; only alpha_CE and the core-envelope boundary are tested (§6.2). The alpha_CE=5 run raises solar Type Ib from 16,295 to 17,694 and lowers Type II from 58,250 to 54,975 (Table D2), indicating more systems survive CE. The paper does not report the CE fraction among SESNe for this run, so it is unknowable from the text whether the <6% bound survives a plausible change in CE efficiency. Moreover, if the stability boundary is too permissive—e.g., if a 0.1 Msun/yr threshold should be lower—more systems would enter CE, and the 'stable MT dominates' conclusion would weaken. This is load-bearing because the abstract states '<6%' without a fiducial-model qualifier, and the paper's own robustness test points in the direction of a higher CE contribution.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper uses POSYDON v2, with its MESA-based single- and binary-star grids, to evolve 2×10^5 systems at six metallicities (0.01–2 Z_sun) and predict which channels produce stripped-envelope supernovae (SESNe). The authors report that stable mass transfer from primary stars dominates, that common-envelope ejection produces <6% of SESNe and secondaries <11%, that the overall SESN/II ratio is nearly metallicity-independent while subtype fractions (Ic/Ib/IIb) depend strongly on Z, that predicted SESN ejecta masses are low and nearly Z-independent, and that the age (progenitor-mass) ordering of subtypes reverses at low Z. The conclusions are supported by a 15-model robustness suite varying α_CE, core-envelope boundary, SN engine, kicks, binary fraction, and interpolation scheme, and by comparisons to environmental and volumetric SN rate data.","tokens_in":47874,"tokens_out":12105,"duration_ms":121571,"significance":"If the results hold, the paper provides a strong quantitative case that binary interactions—specifically stable Roche-lobe overflow rather than common-envelope episodes or single-star winds—are the dominant formation channel of SESNe across metallicity. The predictions are falsifiable: nearly Z-independent ejecta-mass distributions, a subtype-age reversal at Z<0.2 Z_sun, and a near-constant SESN/II ratio. The study is notable for using published, open POSYDON grids (commit 891c5897), for taking classification thresholds from external spectral models rather than fitting, and for an unusually extensive sensitivity analysis. The central caveat is that one headline quantitative claim (CE<6%) is not robust to the paper's own α_CE=5 run, and the subtype-rate comparisons are sensitive to the explosion engine at high Z.","major_comments":[{"comment":"The abstract and conclusion state that the common-envelope (CE) channel contributes <6% of SESNe. From Table 1, the fiducial solar run indeed has a CE-origin fraction of roughly 2–3% among SESNe. However, in the α_CE=5 robustness run (Table D2), Type Ib increases from 16,295 to 17,694 and Type Ic from 420 to 470, while Type II falls from 58,250 to 54,975. Since α_CE changes only CE survival, the net SESN increase of ~1,474 is CE-origin; adding the ~440 CE-origin SESNe of the fiducial run gives at least ~1,900 of 21,428 SESNe, i.e. ~9%, exceeding 6%. The text does not report the CE fraction for this model, so the headline bound is not robust to one of the paper's own tested parameters. Please report CE-origin fractions for all 15 models and qualify the claim.","section":"Abstract; §5.1; §6.2 and Table D2"},{"comment":"The solar IIb/II ratio changes by a factor of 3.3 across explosion engines: 2467/58250=4.2% (default), 4258/51790=8.2% (S+16), and 8410/60641=13.9% (F+12_delayed). Section 5.2 uses the default value to claim that models underpredict observed IIb/II (~12–16% at high Z) and attributes this offset to wind mass loss; the F+12_delayed run in the paper's own Table D2 removes most of that discrepancy. Since the IIb/II trend is central to the subtype-diversity claim and to the quantitative comparison with observations, the conclusions should be stated as engine-dependent, or the paper should discuss which subtype conclusions survive under all three engines.","section":"§5.2; §6.2; Table D2"},{"comment":"The CE<6% conclusion rests in part on POSYDON's stability criteria (Mdot>0.1 Msun/yr, L2 overflow, photon-trapping radius). None of the 15 models varies these thresholds; only α_CE and the core-envelope boundary are changed. Given that the criteria determine how many systems enter CE, a test with, e.g., a lower or higher Mdot threshold would quantify the uncertainty in 'unstable MT is less frequent than previously thought' (§5.1). Without such a test, the stability boundary remains an untested, load-bearing assumption.","section":"§2 (Mass transfer/Common envelope); §6.2"}],"minor_comments":[{"comment":"Typo: 'mettalicity' should be 'metallicity'.","section":"Appendix C, Figure C1 caption"},{"comment":"Percentage notation is inconsistent: e.g., '86.9 (3.06 %)' vs '91.97 % (3.29 %)'; the Type Ib 'Merged' row reads '0.06 0.03 %' without units. Please unify formatting.","section":"Table 1"},{"comment":"The text says '13 distinct binary population models' but Table D2 lists 15 rows including defaults (six variations at solar plus default, seven at subsolar plus default). Please clarify the count.","section":"§6.2; Table D2"},{"comment":"Typo: 'This highligts that the adopted hydrogen-envelope mass threshold...' should be 'highlights'.","section":"§5.2"},{"comment":"Typo: 'core collpase' should be 'core collapse'.","section":"Conclusions, item 5"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Bottom line: this is the first population synthesis study of stripped-envelope SNe that uses POSYDON's detailed MESA binary grids over a wide metallicity range, and the central qualitative claim holds up: stable binary mass transfer, not common envelopes or single-star winds, is the dominant SESN channel, and the SESN/II ratio is roughly flat with metallicity. The new quantitative predictions — CE < 6%, secondary channel < 11%, nearly metallicity-independent ejecta masses, and the reversal of the subtype age ordering at low Z — are genuinely new and testable.\n\nThe paper is unusually transparent. The robustness suite covers 15 models (alpha_CE, core-envelope boundary, SN engine, kicks, binary fraction, interpolation), and the authors explicitly discuss limitations: post-CE residual hydrogen, neglected rejuvenation, and simplified merger products. That honesty earns credit.\n\nThe soft spots are real but not fatal. The abstract states CE < 6% without a fiducial qualifier, and the paper's own alpha_CE=5 run moves Type Ib counts from 16,295 to 17,694 at solar metallicity while reducing Type II. The authors do not report the CE fraction among SESNe for that run, so we cannot tell from the text whether the bound survives a plausible change in CE efficiency. The stability criteria for entering CE are not varied in the sensitivity set, which matters because the CE fraction depends on them. Subtype ratios also depend strongly on the SN explodability prescription (F+12_delayed raises IIb/II from 4% to 15% at solar). The population-run outputs are not archived, only shared on request, which weakens reproducibility.\n\nNone of this undermines the central argument. The qualitative picture — stable MT dominant, CE minor, flat SESN/II — survives the sensitivity tests. The precise subtype fractions should be quoted as model-dependent.\n\nThis paper deserves a serious referee and will likely be published after revisions. The main requested changes would be: hedge the abstract's CE claim, report the CE-channel fraction in the alpha_CE=5 run, and ideally deposit the population outputs. I'd take it to reading group.","headline":"First POSYDON-based SESN population synthesis across metallicities; stable binary mass transfer dominates, with the CE<6% headline needing a fiducial qualifier.","tokens_in":48516,"tokens_out":3135,"would_cite":true,"duration_ms":31719,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"This paper argues that stripped-envelope supernovae are shaped far more by binary companions than by metallicity or stellar winds, with stable mass transfer in binaries the dominant stripping mechanism and common-envelope evolution contribu","keywords":["stripped-envelope supernovae","binary population synthesis","common envelope","metallicity dependence","ejecta masses","supernova subtypes","mass transfer","stellar evolution"],"falsifier":"Compare the stripped-envelope-to-Type-II ratio and the Type IIb/Type Ib split in a volume-limited, untargeted sample of supernovae with host metallicities spanning 0.1 to 2 solar. If the ratio rises steeply with metallicity, or if ejecta masses of Type Ib/IIb supernovae increase toward metal-poor hosts as single-star models predict, the binary-stable-mass-transfer picture would be falsified. A more targeted test: measure the fraction of stripped-envelope supernovae with surviving binary companions on wide orbits; under the paper's picture most should have such companions, while under single-st","tokens_in":47440,"feed_emoji":"💥","tokens_out":8797,"duration_ms":87808,"temperature":0.7,"pith_summary":"This paper argues that stripped-envelope supernovae—explosions of massive stars that have lost their hydrogen envelopes—are shaped far more by binary companions than by metallicity or stellar winds. Using a binary population synthesis code built on grids of detailed stellar-structure models, the authors evolve 200,000 binary systems at each of six metallicities (0.01 to 2 times solar) and classify their explosions by predicted hydrogen and helium content. They find that the common-envelope channel produces less than 6% of these supernovae, secondary stars produce less than 11%, and the rest come from primary stars stripped through stable Roche-lobe mass transfer. The total stripped-envelope rate relative to hydrogen-rich Type II supernovae stays nearly flat across metallicity, while the subtype mix shifts from Type Ic/Ib at high metallicity toward Type IIb at low metallicity. Predicted ejecta masses remain low and roughly metallicity-independent, in contrast to single-star models, giving observational tests for the binary-dominated picture.","feed_headline":"Common-envelope channel supplies under 6% of stripped supernovae","feed_subtitle":"Stable mass transfer, not envelope ejection, sets subtype and keeps ejecta masses flat","key_machinery":"The load-bearing instrument is a binary population synthesis calculation in which every binary is mapped onto grids of detailed stellar evolution simulations, so mass-transfer rates, envelope binding energies, and final core structures come from stellar-structure models rather than fitting formulas. The central mechanism is the post-core-helium-depletion mass-transfer episode: at low metallicity, partially stripped stars retain enough hydrogen to re-expand and fill their Roche lobe again, stripping the envelope further and erasing metallicity differences in ejecta mass. The common-envelope outcome is governed by the alpha/lambda formalism with envelope binding energies computed from the deta","core_discovery":"The paper's central claim is that stable mass transfer in binaries, rather than common-envelope ejection or line-driven winds, is the dominant mechanism producing stripped-envelope supernovae across all metallicities from 0.01 to 2 solar. In the authors' detailed binary grids, unstable mass transfer is rarer than rapid population synthesis codes have assumed, and when it does occur the envelope is usually too tightly bound to be ejected, so common-envelope survivors contribute under 6% of the stripped-envelope population. The majority of progenitors are primary stars that lose their hydrogen envelopes through one or more stable Roche-lobe overflow episodes; a crucial late episode after core","pith_inferences":["If the common-envelope contribution is truly below 6%, the common-envelope channel is unlikely to be the main factory of compact-object mergers among stripped stars; stable mass-transfer products may deserve more attention as gravitational-wave progenitors.","The paper's flat-rate result assumes a binary fraction of 0.6; if low-metallicity galaxies have close-binary fractions near 0.8, as some recent surveys suggest, the predicted stripped-envelope rate would rise with decreasing metallicity, reversing the headline flatness.","The tentative Type I(I)b class is a sharp diagnostic: measuring the true hydrogen threshold in real spectra would let observers choose between the paper's Ib and IIb rate assignments, turning a classification nuisance into a physical measurement.","If the late post-helium-depletion mass transfer is as common as the models imply, many stripped progenitors should explode while still Roche-lobe filling, making polarization and early circumstellar interaction signatures more frequent in low-metallicity stripped supernovae."],"forward_implications":["If the central claim holds, untargeted surveys should see a stripped-envelope-to-Type-II ratio that is nearly flat from 0.01 to 2 solar metallicity, even as the Ib/Ic fractions drop and IIb fractions rise at low metallicity.","Ejecta masses of stripped-envelope supernovae should remain low and roughly constant with host metallicity; a clear rise toward metal-poor hosts would favor single-star stripping instead.","The progenitor age sequence should reverse at low metallicity: Type IIb from the most massive (shortest-lived) progenitors, Type Ib from lower-mass stars with long lifetimes—a testable environmental signature.","Most stripped-envelope progenitors should show signs of stable Roche-lobe mass transfer (e.g., relatively wide surviving binaries or stripped companions) rather than post-common-envelope tight orbits.","Observed subtype-rate differences between surveys may be driven largely by the hydrogen-envelope threshold separating Type IIb and Type Ib; predicting the tentative Type I(I)b class as a distinct category would sharpen the test."],"supporting_citations":[{"why":"Supplies the binary population synthesis method, including the mass-transfer stability criteria and common-envelope treatment the paper's central claim rests on.","marker":"Fragos et al. 2023"},{"why":"Provides the multi-metallicity detailed binary model grids and merger-product treatment used for the population calculations.","marker":"Andrews et al. 2024"},{"why":"Establishes the post-core-helium-depletion re-expansion of partially stripped stars, the mechanism that equalizes ejecta masses across metallicity.","marker":"Laplace et al. 2020"},{"why":"Shows how metallicity shifts the donor's evolutionary stage at first mass transfer, explaining why low-metallicity stripping is partial.","marker":"Klencki et al. 2020"},{"why":"Supplies the explodability prescription (core carbon/oxygen mass and carbon abundance) that decides which stripped cores become supernovae.","marker":"Patton & Sukhbold 2020"},{"why":"Rapid population synthesis baseline whose metallicity-dependent SESN/II ratio is compared against the paper's flat ratio.","marker":"Zapartas et al. 2017a"},{"why":"Semi-detailed population synthesis comparison for SESN rates and the role of the Type IIb fraction.","marker":"Eldridge et al. 2017"},{"why":"Provides the initial orbital period distribution for massive binaries used to initialize the population.","marker":"Sana et al. 2013"},{"why":"The Wolf-Rayet wind mass-loss prescription that, with binary stripping, sets final envelope and ejecta masses.","marker":"Nugis & Lamers 2000"}],"fun_headline_variants":["Stable mass transfer drives most stripped-envelope supernovae","Common-envelope channel under 6% in new stripped supernova model","Stripped supernova rates flat with metallicity, subtypes vary","Ejecta masses stay low across metallicities for stripped supernovae"],"cache_read_input_tokens":2688,"weakest_assumption_plain":"The conclusion that common-envelope evolution contributes less than 6% of stripped-envelope supernovae rests on the model's criteria for when mass transfer turns dynamically unstable and on the assumed common-envelope efficiency; if real envelopes are ejected more easily than the default assumption allows, the common-envelope fraction could climb well above 6%.","fun_headline_variants_meta":{"raw":{"variants":["Stable mass transfer drives most stripped-envelope supernovae","Common-envelope channel under 6% in new stripped supernova model","Stripped supernova rates flat with metallicity, subtypes vary","Ejecta masses stay low across metallicities for stripped supernovae"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.00032,"raw_usage":{"total_tokens":1692,"prompt_tokens":846,"completion_tokens":846,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":590,"completion_tokens_details":{"reasoning_tokens":770}},"tokens_in":590,"tokens_out":846,"duration_ms":8492,"temperature":1.0,"reasoning_tokens":770,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-05T14:36:00.935555+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Compare the stripped-envelope-to-Type-II ratio and the Type IIb/Type Ib split in a volume-limited, untargeted sample of supernovae with host metallicities spanning 0.1 to 2 solar. If the ratio rises steeply with metallicity, or if ejecta masses of Type Ib/IIb supernovae increase toward metal-poor hosts as single-star models predict, the binary-stable-mass-transfer picture would be falsified. A more targeted test: measure the fraction of stripped-envelope supernovae with surviving binary companions on wide orbits; under the paper's picture most should have such companions, while under single-st","supporting_citations":[],"review_version":1}