{"id":"0aeceb73-d49d-4766-8344-4f314656e7ba","arxiv_id":"2501.08969","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":12,"one_line_summary":"Modeling JWST light curves of six Type II supernovae at z = 0.66 - 3.61 yields explosion energies of (0.5 - 3) x 10^51 erg, with two high-energy events and two showing signs of dense circumstellar matter.","lead":"Six distant Type II supernovae found by JWST were modeled by matching synthetic light curves to sparse photometry. Two of them appear unusually energetic, which hints that explosive stellar deaths in the early universe may differ from local ones, though the sample is tiny and selection effects remain.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Both claimed 3e51 erg events (AT 2023adsv and AT 2023adtw) are photometrically classified; if either is not a genuine Type II SN, the central high-energy-fraction claim is unsupported.","rationale":"The reader correctly identifies photometric classification as the weakest link, and the manuscript supports that emphasis: the two 3e51 erg events are precisely the objects without spectroscopic Type II confirmation, while both spectroscopically confirmed SNe have ordinary inferred energies. This makes the high-energy-fraction claim hostage to the classifier for two unusual, heavily reddened or host-dominated transients. My read therefore agrees with the reader's weakest assumption and with a CONDITIONAL verdict rather than a more severe one, because the paper is appropriately cautious and the classification issue is a specific, testable uncertainty rather than an internal contradiction.","tokens_in":20809,"tokens_out":5166,"duration_ms":56590,"concrete_test":"Independently reclassify AT 2023adsv and AT 2023adtw using the full photometry with an MCMC light-curve fit that includes Type II, Type IIn, SLSN-I, and broad-lined Ic templates with host extinction as a free parameter; for AT 2023adsv, also reduce the existing DDT #6541 NIRSpec data after subtracting a host-galaxy template and search for broad H-alpha or P-Cygni features. If an alternative SN type fits either object comparably, or if no broad hydrogen features appear for AT 2023adsv, the high-energy-fraction claim should be downgraded; if both objects are robustly classified as Type II by this independent check, the concern is retired.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim of an excess of high-energy Type II SNe rests on exactly two objects: AT 2023adsv (z=3.61, E=3.0 B) and AT 2023adtw (z=0.657, E=3.0 B). Both are photometrically classified, while the two spectroscopically confirmed SNe in the sample have ordinary energies (1.2-2.3 B). Section 3.1 states that AT 2023adsv's spectrum is dominated by host-galaxy lines and 'it is difficult to obtain the SN spectral type,' so its Type II classification is purely the 100% STARDUST2 photometric probability from DeCoursey et al. (2025). AT 2023adtw is likewise photometric, and its SED requires E(B-V)=1.3-1.5 mag with an unexplained blue excess in F090W/F115W. If either object is actually a Type IIn, a superluminous SN, or a broad-lined Ic, the inferred 3e51 erg energy and the fraction argument both collapse, because the spectroscopically confirmed subsample shows no high-energy events. The paper's own caveats ('difficult to draw a firm conclusion', 'potential observational biases') do not fix the logic: the headline statement is a statement about Type II SNe, but two of the six members, including both high-energy members, lack spectroscopic confirmation of their Type II nature.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper models the rest-frame optical/near-IR light curves of six Type II SNe at 0.657 <= z <= 3.61 discovered by the JADES transient survey, using the radiation-hydrodynamics code STELLA and low-metallicity Z = 0.1 Zsun MESA progenitor models. The model parameters are varied by eye, with explosion epoch, explosion energy, host extinction, and in two cases confined dense CSM properties treated as free parameters. The authors report two SNe (AT 2023adsv and AT 2023adtw) with explosion energies of 3 x 10^51 erg, four with energies typical of local Type II SNe, evidence for confined dense CSM in two objects, and high host extinctions for two lower-redshift objects. They cautiously suggest that the fraction of high-energy Type II SNe may be higher at high redshift, while acknowledging the small sample and potential biases.","tokens_in":21213,"tokens_out":5268,"duration_ms":54057,"significance":"If the inferred properties are correct, this is one of the first population-level looks at Type II SNe beyond z ~ 1, and it would suggest that energetic explosions and confined dense CSM exist at high redshift, with JWST able to uncover heavily obscured SNe. The paper is useful as a pilot study, and the independent cross-check of AT 2023adsv by Coulter et al. (2025) is a notable strength. However, the statistical reach is limited by the sample size, by the reliance on photometric classification for both high-energy objects, and by the lack of quantitative fit assessment.","major_comments":[{"comment":"The headline claim of a high fraction of 3 x 10^51 erg Type II SNe rests entirely on two photometrically classified transients, AT 2023adsv and AT 2023adtw. Section 3.1 states that AT 2023adsv's spectrum is dominated by host-galaxy lines and that the SN spectral type is difficult to obtain, while AT 2023adtw has no spectroscopic SN classification. The two spectroscopically confirmed SNe in the sample, SN 2023adto and SN 2023adtu, have inferred energies of 1.2-2.3 B. If either high-energy object is not a genuine Type II SN, the central high-energy-fraction claim loses its support. The text should separate the spectroscopically confirmed and photometrically classified subsamples when stating conclusions, and should explicitly present the high-energy fraction as conditional on the photometric classifications being correct.","section":"Secs. 3.1, 3.6, Table 1"},{"comment":"The light-curve fits are selected by eye, with no quantitative goodness-of-fit metric or uncertainty estimate for the inferred parameters. With free explosion energy, host extinction, and explosion epoch, the reported values such as E = 3.0 B versus E = 2.0-2.5 B are not demonstrated to be distinct. The degeneracy is particularly relevant for AT 2023adtw, where high extinction E(B-V) = 1.3-1.5 mag is adopted simultaneously with the high explosion energy. Please provide a quantitative comparison of the model grid to the photometry, such as residual-based fit statistics or confidence regions, or at least show representative alternative models that are rejected by the data.","section":"Sec. 2.3 and Figs. 2-10"},{"comment":"For AT 2023adtw, the observed SEDs show a significant flux excess in F090W and F115W at the first two epochs, and the text states that its origin is not clear. These are exactly the bands that would constrain a hot component or a different extinction law, and the adopted E = 3.0 B, E(B-V) = 1.5 model does not reproduce this excess. Without identifying this excess or showing that it cannot affect the inferred explosion energy, the high-energy and high-extinction conclusions for this object remain insecure.","section":"Sec. 3.6, Fig. 11"},{"comment":"The discussion of observational bias (Fig. 12) demonstrates only that a standard Type II SN would be above the detection limit, but it does not account for the sample-selection criteria of 100% STARDUST2 photometric probability and at least three observed epochs, which favor brighter and better-sampled events. Moreover, one of the two high-energy objects, AT 2023adtw at z = 0.657, is at the low-redshift end of the sample; among the five objects at z > 1, only one is inferred to be high-energy. The claim of a high-redshift excess should therefore be softened to reflect that the statistical basis is at most one high-energy event at high redshift.","section":"Sec. 4, Fig. 12, Table 1"}],"minor_comments":[{"comment":"The text refers to 'SN 2023dtu' in one place; this should be 'SN 2023adtu'.","section":"Sec. 3.5"},{"comment":"The figure caption lists the same MJD values (60216.9, 60276.3, 60310.4) as Figure 5; please verify that these are the correct epochs for AT 2023adtw.","section":"Fig. 11 caption"},{"comment":"The term 'photometrically confirmed' is used for objects with 100% STARDUST2 probability; 'photometrically classified' would be more precise, since classification is not confirmation.","section":"Sec. 2.1"},{"comment":"The ZAMS mass column gives ranges, but the text states that ZAMS masses are poorly constrained; consider reporting the full grid or marking the column as 'unconstrained' to avoid implying a meaningful constraint.","section":"Table 1"},{"comment":"Marking the redshifts of the six sample SNe on the magnitude-redshift plane would make the selection bias discussion more concrete.","section":"Fig. 12"}],"recommendation":"major_revision","confidential_remarks":"This is a worthwhile first-look study, and the authors are commendably cautious in parts of the discussion. The main weakness is that the abstract's two-event high-energy claim rests on photometric classifications and by-eye fits, so the conclusions need to be reframed as conditional. I do not think rejection is warranted; the authors can address the issues by tightening the language, separating confirmed from classified objects, and adding quantitative model comparison where possible. The independent consistency with Coulter et al. for AT 2023adsv is a strong point in favor of the paper."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague,\n\nThe JADES Type II SN paper is the first systematic attempt to estimate explosion energies, extinctions, and CSM for a sample of ordinary core-collapse SNe at 0.7<z<3.6. That alone makes it worth reading. The modeling is careful: low-metallicity MESA progenitors, STELLA light curves, host SED fits with Prospector, and the authors are upfront about the limits of by-eye fits and the small sample. For AT 2023adsv, the highest-redshift object, Coulter et al. get similar properties with different metallicity models, which is a genuinely useful cross-check.\n\nThe soft spot is exactly where the stress-test points. Both 3e51 erg events—AT 2023adsv and AT 2023adtw—are photometrically classified. The two spectroscopically confirmed SNe have ordinary energies (1.2–2.3 B). So the claim that the high-energy fraction is larger at high z does not have spectroscopic support; if either photometric object is actually a Type IIn, a superluminous SN, or a broad-lined Ic, the fraction argument collapses. The paper does say the conclusion is tentative, but the abstract still states the two high-energy events as a finding. That needs a more decisive caveat or a restructure that leads with the spectroscopically confirmed subsample.\n\nThe other limitations are minor relative to this. The by-eye fits have no error bars or goodness-of-fit metrics, and the code isn't public, but this is consistent with how the field treats sparse JWST light curves. The unexplained blue excess in AT 2023adtw's SED is acknowledged but not explained; it doesn't kill the extinction estimate, but it is a loose end. The CSM and extinction claims are plausible and follow from the same modeling; they are not the load-bearing part of the paper.\n\nWho gets value: anyone working on JWST transient surveys, high-z core-collapse SNe, or cosmic chemical enrichment. The sample is unique and the paper is honest. I'd send it to review—it deserves referee time, and with a revision that either strengthens the classification case or softens the high-energy claim, it will be a useful reference point.","headline":"First real look at Type II SNe at z>1, but the high-energy fraction claim leans on two photometric objects and needs a softer frame.","tokens_in":21907,"tokens_out":3400,"would_cite":true,"duration_ms":32476,"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":"Far-off Type II supernovae include a high-energy excess.","keywords":["Type II supernovae","high-redshift supernovae","supernova light curves","explosion energy","circumstellar matter","host galaxy extinction","core-collapse supernovae","infrared transient survey"],"falsifier":"Uncontaminated spectroscopy of AT 2023adsv: if the supernova's own spectrum showed no hydrogen P Cygni lines but instead features of another transient class, the claim of a $\\sim3\\times10^{51}$ erg Type II event at $z=3.61$ would collapse. A larger sample at the same survey depth that recovered the local high-energy fraction would also falsify the proposed redshift trend.","tokens_in":20613,"feed_emoji":"💥","tokens_out":6800,"duration_ms":71998,"temperature":0.7,"pith_summary":"This paper estimates the explosion energies and progenitor masses of six Type II supernovae (exploding massive stars with hydrogen-rich envelopes) found at redshifts $0.66$ to $3.61$ in a deep infrared survey. It finds that two of the six blasted out about three times the energy of typical local Type II supernovae, while the other four match local energies. If true, the population of exploding massive stars in the early universe may be systematically more energetic, and at least some distant Type II supernovae are surrounded by dense gas shed by the star before death. These results give a first look at ordinary, not just superluminous, supernovae at these distances, and they show that infrared surveys can catch both clean and heavily dust-obscured explosions.","feed_headline":"Distant supernovae show a high-energy excess","feed_subtitle":"Six far-off stellar explosions modeled from infrared light curves include two with triple the usual blast energy.","key_machinery":"The argument is carried by the Type II plateau relation: during the hydrogen-recombination plateau, a supernova's luminosity is set mainly by the explosion energy and pre-explosion radius, while the plateau duration is set by the envelope mass. The authors build low-metallicity ($0.1\\,Z_\\odot$) red supergiant progenitors with masses $12{-}24\\,M_\\odot$, explode them with a radiation-hydrodynamics code that tracks the evolving spectrum, redshift the synthetic spectral energy distributions, and compare them directly to the observed multi-filter photometry. Explosion energy is treated as a free parameter, and a parameterized wind-density law $\\rho\\propto\\dot{M}/r^2 v(r)$ is used to add confined dense circumstellar matter at $10^{15}$ cm when the early epochs are too bright to match a bare plateau model.","core_discovery":"The paper's central claim is that the first six well-observed Type II supernovae beyond $z\\approx0.7$ include a larger share of very energetic explosions than local samples: two events, including AT 2023adsv at $z=3.61$, require roughly $3\\times10^{51}$ erg of kinetic energy, compared with the $(0.5{-}2)\\times10^{51}$ erg typical at low redshift. The authors are careful that the sample is small and subject to selection, but they show that a standard Type II supernova would still be detectable above the survey depth at $z>4$, so the apparent excess is not simply a brightness bias. They also find that two of the six light curves are better matched when a confined, dense circumstellar shell of about $0.23\\,M_\\odot$ is added, indicating that the mass-loss behavior seen around local Type II supernovae also operates at high redshift. Progenitor masses could not be tightly constrained from the sparse light curves, and host extinctions range from zero up to $E(B-V)\\approx1.3{-}1.5$ mag for two events.","pith_inferences":["The strongest near-term test is spectroscopic: an uncontaminated spectrum of AT 2023adsv that shows hydrogen lines would lock in the highest-energy event, while a spectrum showing another supernova class would reduce the claimed high-energy fraction from two of six to one of six.","If the excess survives larger samples, the authors' models could be turned into a forward model of survey detectability to separate a true redshift trend in explosion energies from residual selection effects.","Confined circumstellar matter around high-redshift supernovae would make those explosions sites of particle acceleration in the early universe, so future diffuse high-energy neutrino analyses could be compared against the CSM incidence estimated here."],"forward_implications":["If the high-energy fraction is real, the earliest massive-star deaths in low-metallicity galaxies were more violent than today's, with consequences for early element production and feedback.","The presence of confined dense circumstellar matter at high redshift means the unknown mass-loss mechanism that creates these shells is not limited to solar-metallicity environments.","Because standard Type II supernovae would be detectable above this survey depth at $z>4$, continued monitoring of the same field should yield a statistically usable high-redshift sample rather than only the brightest explosions.","Two highly reddened events show that infrared surveys recover dust-obscured supernovae that optical surveys miss, keeping the inferred high-energy fraction from being purely a clean-line-of-sight bias."],"supporting_citations":[{"why":"Supplies the discovery sample, photometric classifications, and light-curve photometry that define the six analyzed events.","marker":"DeCoursey et al. (2025)"},{"why":"Provides the host-galaxy redshift and metallicity of AT 2023adsv and an independent analysis whose energy and CSM conclusions agree.","marker":"Coulter et al. (2025)"},{"why":"Supplies the spectroscopic confirmations of SN 2023adto and SN 2023adtu and the spectra that anchor redshifts.","marker":"Egami et al. (in preparation)"},{"why":"Provides the Bayesian light-curve classifier used to identify the four photometrically classified events as Type II supernovae.","marker":"Rodney et al. (2014)"},{"why":"Provides the radiation-hydrodynamics code used to compute the synthetic multi-band light curves.","marker":"Blinnikov et al. (1998)"},{"why":"Establishes the plateau brightness and duration dependence on explosion energy and envelope mass that the inference rests on.","marker":"Kasen & Woosley (2009)"},{"why":"Supplies the local benchmark that confined dense circumstellar matter is common around nearby Type II supernovae.","marker":"Förster et al. (2018)"},{"why":"Provides the local Type II supernova explosion-energy distribution that the high-redshift energies are compared against.","marker":"Martinez et al. (2022)"}],"fun_headline_variants":["Two early supernovae pack triple the typical blast energy","JWST finds distant supernovae may be unusually energetic","High-redshift supernovae hint at a high-energy excess","First far-off supernovae show a surplus of powerful blasts"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"All six flashes are Type II supernovae; the most energetic one is classified only by photometry because its spectrum is dominated by host-galaxy light, so one misclassification would lower the high-energy fraction from two of six to one of six.","fun_headline_variants_meta":{"raw":{"variants":["Two early supernovae pack triple the typical blast energy","JWST finds distant supernovae may be unusually energetic","High-redshift supernovae hint at a high-energy excess","First far-off supernovae show a surplus of powerful blasts"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000249,"raw_usage":{"total_tokens":1613,"prompt_tokens":1070,"completion_tokens":543,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":686,"completion_tokens_details":{"reasoning_tokens":473}},"tokens_in":686,"tokens_out":543,"duration_ms":6381,"temperature":1.0,"reasoning_tokens":473,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-10T20:13:00.783194+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Uncontaminated spectroscopy of AT 2023adsv: if the supernova's own spectrum showed no hydrogen P Cygni lines but instead features of another transient class, the claim of a $\\sim3\\times10^{51}$ erg Type II event at $z=3.61$ would collapse. A larger sample at the same survey depth that recovered the local high-energy fraction would also falsify the proposed redshift trend.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Establishes the plateau brightness and duration dependence on explosion energy and envelope mass that the inference rests on."}],"review_version":1}