{"id":"28c174fd-7211-41a3-be2e-2ddcdfe53d1b","arxiv_id":"2608.02022","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":7,"one_line_summary":"Using BPASS, only binary progenitors whose mass loss forms a circum-binary disc reproduce the luminosities and rise times of stripped-envelope interacting supernovae.","lead":"This paper uses the BPASS stellar evolution grid to ask whether ordinary winds or circum-binary discs can produce the dense material that stripped-envelope interacting supernovae (Ibn/Icn) need. It concludes that only binary systems with a circum-binary disc reproduce observed light curves, and that early high-frequency radio observations can test this.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Helium-giant winds are treated with WR prescriptions for all models; §4 admits correcting this would shift ~84% of expected SEISNe, so the pure-wind null and the binary-channel rates are not yet robust.","rationale":"The paper's headline is a null result for single-star progenitors plus a rate-based argument for binaries. Both rest on the CSM reconstruction in §2.3, where all winds are assigned WR velocities and BPASS mass-loss rates. The authors flag the helium-giant issue twice: §2.3 asserts it does not influence conclusions, while §4 says it would reduce expected SEISNe rates, change the metallicity/initial-mass parameter map, and affect models constituting 84% of expected SEISNe. This is a material, quantified uncertainty, and the reader's weakest_assumption correctly identifies it. The concern is not that the authors are certainly wrong, but that the paper does not run the recalibration needed to show the conclusion is stable. A pure-wind path could conceivably open if slower helium-giant winds make CSM denser close to the star; at minimum, the wind-capture rate and Figure 5 would shift. The free-streaming scenario remains a lower bound and may preserve a binary channel, so a rejection is not warranted; the appropriate verdict stays CONDITIONAL. The proposed test is a direct rerun with the corrected helium-giant wind prescription and would settle whether this caveat is cosmetic or drives the headline.","tokens_in":24484,"tokens_out":19556,"duration_ms":235271,"concrete_test":"Recompute the CSM and light-curve peak parameters for all 30,153 selected models using Sander & Vink (2020) / Vink (2017) helium-star mass-loss rates and terminal velocities for models with final mass ≲6 M⊙, keeping the WR prescription otherwise, and regenerate the pure-wind panel of Figure 4. Determine whether any non-binary model (types −1 or 0) falls in the observed SEISNe box (L_peak 10^42–10^45 erg s^-1, t_peak 1–20 d). Also recompute the wind-capture expected rate; if it drops to the free-streaming rate, the binary-channel rate comparison changes materially.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim—only CBD scenarios, hence no single-star models, match SEISNe peak parameters—depends on building the CSM with BPASS wind mass-loss rates and Nugis & Lamers (2000) WR terminal velocities (Eqs. 3–4) for every selected model (§2.3). The paper itself notes that many models end as helium giants, for which these rates and velocities are probably lower (Sander & Vink 2020; Vink 2017). Section 4 then states that models with final mass ≲6 M⊙ make up 84 per cent of the expected SEISNe and that 'correct helium giant mass loss rates would likely reduce our expected SEISNe from our models, and change the metallicity and initial mass model parameters to those seen in the free streaming scenario.' That is hard to square with §2.3's assertion that 'This difference in mass-loss does not influence the conclusions drawn from our modelling.' Because lower terminal velocities concentrate wind CSM closer to the progenitor, the pure-wind scenario—the basis for excluding single-star progenitors—could potentially move models into the observed 10^42–10^45 erg s^-1, 1–20 d region. At minimum, the wind-capture rate used to support the binary-channel interpretation would drop toward the free-streaming lower limit. The paper does not perform this recalibration, so the headline conclusion depends on an unquantified and admittedly inappropriate wind prescription.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper aims to constrain the progenitors of stripped-envelope interacting supernovae (SEISNe; Ibn/Icn) by combining the BPASS v2.2 single/binary stellar evolution grid with simple analytical CSM and interaction-powered light-curve models. From 30,153 hydrogen-poor core-collapse models, the authors reconstruct the CSM from the last 100 kyr of wind and RLOF mass loss under three geometric scenarios: a spherical pure-wind distribution; a circum-binary disc that captures intersecting wind ('wind capture'); and a CBD with freely streaming wind ('free streaming'). Using Eq. 5 for the interaction luminosity and a fixed 56Ni/ejecta ratio, they compare peak luminosity and rise time to a 1–20 d, 10^42–10^45 erg/s box. They find the pure-wind scenario (including all single-star models) cannot populate this box, while both CBD scenarios can, yielding event rates 0.10% and 0.026% of CCSNe; they infer binary progenitors with ZAMS masses ~14–40 M⊙ at ≥ Z⊙ and ~30–40 M⊙ below Z⊙. They also model radio synchrotron emission, concluding early (<8 d) high-frequency (≥70 GHz) observations are needed.","tokens_in":24815,"tokens_out":8192,"duration_ms":95463,"significance":"If the central result holds, it is an important population-level argument that SEISNe are produced by massive binaries with a CBD, with concrete predictions for rate, environment metallicity, and radio detectability. The paper's strengths include the large model grid (13 metallicities), the explicit three-scenario comparison, the use of independent observables (radio-derived CSM densities of Sfaradi et al. 2025), and an unusually candid discussion of caveats. The method is transparent and reproducible. However, the headline conclusion is sensitive to two admitted and partly contradictory modelling assumptions—the WR-like wind prescription applied to helium giants and the 100% kinetic-to-radiation efficiency—and the quantitative impact on the rates and progenitor ranges is not evaluated. The core comparison is internally consistent, but the robustness of the central claim is not yet established.","major_comments":[{"comment":"The CSM is constructed using WR terminal velocities (Eqs. 3–4) and BPASS WR mass-loss rates for every selected model, including stars with final mass ≲6 M⊙ that the paper itself identifies as helium giants. Section 2.3 states that this difference 'does not influence the conclusions drawn from our modelling', but Section 4 states that models ending with mass ≲6 M⊙ make up 84 per cent of the total expected SEISNe and that 'correct helium giant mass loss rates would likely reduce our expected SEISNe from our models, and change the metallicity and initial mass model parameters to those seen in the free streaming scenario.' These statements are in direct tension. Because the pure-wind scenario is the basis for the headline exclusion of single-star progenitors, and because lower terminal velocities concentrate wind CSM closer to the progenitor, the central claim is not robust until this recali","section":"§2.3 / §4"},{"comment":"The light-curve luminosities assume 100 per cent conversion of CDS kinetic energy into radiation. The paper cites Khatami & Kasen (2024) as giving 10–50 per cent for the relevant CSM masses and radii. Since the 'match' condition is a hard cut at L_peak ≥ 10^42 erg/s, an efficiency reduction by a factor 2–10 could move a substantial fraction of the CBD models, and possibly the entire free-streaming scenario, below the threshold. The stated compensation (10° opening angle, constant-density disks) is plausible but is not quantified. Please propagate the efficiency range through the rates and progenitor-mass/metallicity maps, or provide an explicit bracketing of the selection.","section":"§2.4 / Eq. (5) / §4"},{"comment":"The adopted 56Ni-to-ejecta ratio of 1:14 is acknowledged to be likely too high for SEISNe (Moriya & Maeda 2016; Perley et al. 2022b). Although the interaction power is said to dominate at peak, the 'peak luminosity' used for the Fig. 4 selection includes the 56Ni contribution at the interaction peak. For models near the 10^42 erg/s boundary, the Ni contribution could decide membership. A short sensitivity test varying the ratio (e.g., 1:50 or 1:100) would remove this as a concern and strengthen the central claim.","section":"§2.4 / §4"}],"minor_comments":[{"comment":"Typo: 'out modelling' should be 'our modelling' in the sentence 'We therefore assume for the rest of out modelling...'.","section":"§2.3"},{"comment":"The figure overlays Type Ib (circles) and Type Ic (triangles) points alongside Ibn/Icn data, but the text defines SEISNe as Ibn/Icn. Please clarify whether the selection box is based on Ibn/Icn only or includes non-interacting stripped-envelope SNe, and whether this affects the interpretation.","section":"Figure 4"},{"comment":"The caption says 'Above the dot-dashed line all all the models that populate the region are merger models' (typo 'all all'), and the text states these are 'all single star models formed from mergers'. Please reconcile the wording: merger products are single stars in BPASS, but the sentence could be misread as excluding single-star channels.","section":"§3.2.1 / Figure 6"},{"comment":"The Conclusions item (i) says 'we can not definitively state that binary interactions are required for SEISNe', whereas the Abstract states 'without phenomena such as eruptive mass loss, SEISNe require massive stars in binary systems'. Please harmonize the strength of the claim in the Abstract with the more cautious phrasing in the body.","section":"§4"}],"recommendation":"major_revision","confidential_remarks":"The main issue is the internal contradiction between §2.3 ('does not influence the conclusions') and §4 ('84 per cent... likely reduce our expected SEISNe... change... to free streaming'). This is not a matter of style; the paper itself identifies the affected fraction as 84%. I believe it is fixable with a recalibration or a quantitative robustness study, but the current version does not support the abstract's strong 'only CBD scenarios' claim. The efficiency and 56Ni assumptions are secondary but should also be propagated if the rates and progenitor ranges are to be considered final."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Short version: this is a genuinely new screen of the BPASS grid, and the radio observing strategy is the clearest deliverable. But the headline conclusion—that no single-star model can make SEISNe—is weaker than the abstract implies, and the authors half-admit it in their own caveat section.\n\nWhat's new: nobody has used the full BPASS v2.2 grid with explicit reconstruction of last-100-kyr wind and RLOF mass loss to test three CSM geometries against SEISNe peak parameters. That is a fair and useful thing to do. The paper also does a decent job comparing to observed CSM densities from radio and to observed rates, and it identifies an actionable observational test: early (<8 d) high-frequency (>70 GHz) radio, away from the disc plane. That result is insensitive to most of the modelling uncertainties.\n\nWhere it's soft: the pure-wind null depends on the wind mass-loss rates and terminal velocities applied to low-mass helium giants. The paper treats all selected models as WR stars (Nugis & Lamers 2000 velocities), then notes in Section 4 that most of the expected events come from final masses ≲6 M_sun, where Sander & Vink and Vink suggest lower rates and velocities. The stress test is right: Section 2.3 says this doesn't affect the conclusions, but Section 4 says it would 'likely reduce our expected SEISNe... and change the metallicity and initial mass model parameters.' Those can't both be true. Lower terminal velocities concentrate wind CSM closer in, so it is plausible, not guaranteed, that some pure-wind models move into the observed peak-luminosity/rise-time box. The 100% kinetic-to-radiation efficiency (Khatami & Kasen give 10-50%) pushes the same direction. So the 'no single stars' claim is not yet robust. The binary/CBD channel is on firmer ground because the disc mass in the free-streaming scenario comes primarily from RLOF, which is not affected by the wind prescription; that scenario also matches observations, at a lower rate. Rates are formally consistent but the numbers could shift substantially.\n\nAlso worth noting: the paper does not deposit its CSM construction code or figure data (\"available upon reasonable request\"), which is a solvable problem.\n\nWho it's for: anyone working on SEISNe, interacting SNe, or massive binary evolution. It deserves referee time. It is not ready to be accepted as-is, mainly because the main null result needs a re-run with appropriate helium-giant mass loss and a lower efficiency before it can be stated as strongly as the abstract does. I'd want to see the revised version after that re-run.","headline":"Solid, honest population synthesis screen; the binary/CBD result is plausible and the radio strategy is useful, but the 'no single stars' claim rests on a wind prescription the authors themselves admit is wrong for most of their events.","tokens_in":25395,"tokens_out":3125,"would_cite":true,"duration_ms":31504,"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":"The paper argues that stripped-envelope interacting supernovae are a binary phenomenon: only circum-binary discs, never single-star winds, reproduce the observed light curves.","keywords":["stripped-envelope interacting supernovae","Type Ibn supernovae","Type Icn supernovae","circum-binary disc","circumstellar material","BPASS stellar evolution","supernova progenitors","radio synchrotron emission"],"falsifier":"A well-observed nearby (<50 Mpc) Ibn/Icn event with polarimetry indicating a line of sight away from any disc plane: if ALMA-class high-frequency (~100 GHz) observations within 8 days find no compact-disc synchrotron flare above the predicted flux, while single-star helium-giant models with corrected wind rates can match the light curve, the central claim would be refuted.","tokens_in":24352,"feed_emoji":"💥","tokens_out":7420,"duration_ms":78784,"temperature":0.7,"pith_summary":"Stripped-envelope interacting supernovae (SEISNe)—rare hydrogen-poor explosions such as Type Ibn and Icn that show intense interaction with surrounding matter—have unclear progenitors. This paper uses the BPASS stellar evolution model grid, 30,153 models spanning 13 metallicities, to reconstruct what surrounds each progenitor during its last 100,000 years and to compute what the resulting supernova light curve would look like. It finds that a spherically symmetric wind produced by any model, including all single stars, cannot make the circumstellar material dense enough close to the star to match observed SEISNe. Only scenarios in which Roche lobe overflow builds a circum-binary disc—a disc of material orbiting both stars—reproduce the observed peak luminosities and rise times, at rates consistent with the observed fraction of Ibn events. The paper concludes that, without additional phenomena such as eruptive mass loss, SEISNe require massive stars in binary systems.","feed_headline":"Binary discs, not stellar winds, power stripped-envelope supernovae","feed_subtitle":"Rare hydrogen-poor supernovae need a binary companion to build the dense disc that lights them up.","key_machinery":"The circum-binary disc (CBD) is the central object: material lost through Roche lobe overflow in the final 100,000 years is placed in a constant-density disc with a 10-degree opening angle between ~3 and ~100 times the binary separation, with winds either captured into it (upper density limit) or streaming through it (lower limit). The light curve is computed from an analytic inelastic-collision formula in which the supernova ejecta form a cold dense shell that sweeps up constant-density CSM shells, converting 100% of the lost kinetic energy into radiation, plus a fiducial 56Ni radioactive decay component. The diagnostic comparison is peak luminosity versus rise time against the observed Ibn","core_discovery":"On its own terms, the paper's discovery is that the observed peak luminosities and rise times of stripped-envelope interacting supernovae can be produced by binary progenitors whose mass transfer in the last 100,000 years concentrates material into a circum-binary disc, and that no single-star wind model in the grid can do so. The pure-wind scenario fails because wind mass loss spreads too little mass too far; placing the same RLOF-ejected mass into a compact disc yields the steep density profile required. The expected progenitors are primary stars in binaries with ZAMS masses of 14–40 solar masses at or above solar metallicity and 30–40 solar masses at lower metallicity. Radio modelling the","pith_inferences":["Beyond the paper: because 84% of the expected events come from models whose final stars are helium giants rather than Wolf-Rayet stars, and those giants probably have slower, weaker winds, correcting that assumption could shrink the matching parameter space and shift it toward the free-streaming limit; the binary conclusion would survive only if such winds still fall short of building a dense clos","Beyond the paper: the same CSM reconstruction could be applied to Type Icn/Ien and other hydrogen-poor interacting transients, testing whether a continuum of stripping levels shares one binary-disc channel.","Beyond the paper: the disc geometry makes a testable polarimetric prediction—early observations within days of explosion should show higher polarization than later epochs, since the photosphere initially forms in the aspherical disc; the current late-time low-polarization measurements do not contradict this.","Beyond the paper: if eruptive mass loss proves common in massive stars, the strong claim that binaries are required would soften, but the rate match still leaves the binary-disc channel as the dominant explanation for the observed Ibn/Icn population."],"forward_implications":["Single stars in the grid cannot power SEISNe light curves from wind mass loss alone; a binary companion, or some additional mass-loss mechanism like eruptions, is needed to make the CSM dense and close-in.","SEISNe should be preferentially found in high star-formation, high-metallicity environments, because at super-solar metallicity the progenitors are 14–40 Msun primaries while at sub-solar metallicity only 30–40 Msun primaries work.","The predicted rate from the wind-capture scenario (0.10% of core-collapse supernovae) is consistent with the observed Ibn fraction, and the free-streaming lower limit (0.026%) remains formally consistent.","Radio detection of a CBD requires observations within about 8 days and at frequencies above ~70 GHz for sources within about 100 Mpc, and only for viewing angles outside the disc plane; later or in-plane observations see only wind-dominated CSM.","Existing radio-derived CSM densities, probed beyond ~10^15 cm, agree with the wind component of the models and therefore do not test the disc scenario."],"fun_headline_variants":["Binary discs explain stripped-envelope supernova brightness","Supernova light requires binary partner, not single-star wind","No single star can build the disc that lights these supernovae","Stripped supernovae reveal their binary-born circumstellar discs","Binary stars create the discs that power rare supernovae"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The conclusion rests on assuming the BPASS wind mass-loss rates and terminal velocities are correct in the final 100,000 years, including for stars ending below about 6 solar masses that are treated as Wolf-Rayet stars but are likely helium giants with weaker, slower winds—the models that supply 84% of the expected events.","fun_headline_variants_meta":{"raw":{"variants":["Binary discs explain stripped-envelope supernova brightness","Supernova light requires binary partner, not single-star wind","No single star can build the disc that lights these supernovae","Stripped supernovae reveal their binary-born circumstellar discs","Binary stars create the discs that power rare supernovae"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000515,"raw_usage":{"total_tokens":2403,"prompt_tokens":880,"completion_tokens":1523,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":624,"completion_tokens_details":{"reasoning_tokens":1440}},"tokens_in":624,"tokens_out":1523,"duration_ms":10820,"temperature":1.0,"reasoning_tokens":1440,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-04T16:24:24.974957+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A well-observed nearby (<50 Mpc) Ibn/Icn event with polarimetry indicating a line of sight away from any disc plane: if ALMA-class high-frequency (~100 GHz) observations within 8 days find no compact-disc synchrotron flare above the predicted flux, while single-star helium-giant models with corrected wind rates can match the light curve, the central claim would be refuted.","supporting_citations":[],"review_version":1}