{"id":"6c0d4c9a-5b93-404b-9766-72f143623f34","arxiv_id":"1909.01993","paper_version":2,"verdict":"REJECT","confidence":"HIGH","novelty_score":5.0,"correctness_risk":"high","formal_verification":"none","parameter_count":5,"one_line_summary":"A proton blazar model with pp interactions against cold jet protons is fitted to three IceCube blazars, reproducing their gamma-ray SEDs and neutrino counts, and attributing the 13-event 2014-2015 flare to PKS 0502+049.","lead":"The paper tests a proton blazar model in which fast protons in a jet hit slower, cold protons to make neutrinos and gamma rays, against three blazars linked to IceCube neutrino events. The model is claimed to fit the gamma-ray and neutrino data for all three, with the 2014-2015 thirteen neutrino events assigned to the nearby blazar PKS 0502+049.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 13-event match is built on a 158-day integration of a flaring-state rate that PKS 0502+049 only sustains for ~23 days; time-weighting the same model gives ~1.7 expected events, not 10.85.","rationale":"Read in good faith, the paper's central claim is that the proton blazar model consistently explains all three IceCube associations, with the new element being PKS 0502+049's production of the 2014-15 13-event neutrino flare. The TXS 2017 and GB6 fits (Nνµ = 0.74 and 0.52) are presented as consistency checks and are plausible, though not decisive. The load-bearing step is the PKS 0502+049 calculation in Sec. IV C. The reader's weakest_assumption correctly identifies that the predicted 10.85 events are obtained by applying flaring-state parameters to the full 158-day window. I checked the manuscript: Sec. IV C places the first active phase at MJD 56860–56960 and the Fig. 4 caption uses MJD 56909.8–56922.2 for the fitted flaring SED, while the IceCube window is MJD 56937.81–57096.21. Only ~23 days overlap at most. Time-weighting the model's own fluxes gives about 1.7 expected events, which is incompatible with 13 ± 5 at 3.5σ. The same issue also affects the quoted Nνµ = 5.2 for α_p = -2.2. The source-association concern (1.2° offset) is secondary; even granting the association, the time integration breaks the event-rate claim. I therefore agree with the reader's REJECT verdict and recommend no change.","tokens_in":18648,"tokens_out":6294,"duration_ms":58575,"concrete_test":"Recompute Eq. (11) for PKS 0502+049 with a time-dependent state: use the flaring-state differential neutrino flux for the actual overlap days within MJD 56937.81–57096.21 (at most MJD 56937.81–56960, i.e. τ_flare ≈ 23 d; or τ_flare = 0 if the fitted active sub-phase MJD 56909.8–56922.2 is the relevant one) and the quiescent-state flux for the remaining days, then compare the total expected Nνµ with 13 ± 5. If the result is ≈1.7 (or ≈0.1), the central 2014-15 explanation fails; if the authors instead intend the flaring rate to be sustained for the full 158 d, they need to show contemporaneous gamma-ray flaring over the whole window.","verdict_should_be":"UNCHANGED","load_bearing_attack":"In Sec. IV C the expected muon-neutrino count for PKS 0502+049 is quoted as Nνµ = 10.85 for α_p = -2.1, 'in 32 TeV and 3.6 PeV energy range in 158 days for the flaring VHE emission state' (Eq. 11 with τ = 158 d; Table I). This is the number used to explain IceCube's 13 ± 5 events in the MJD 56937.81–57096.21 box window. However, the same section states that the source's first active phase is MJD 56860–56960, and the Fig. 4 caption fits the flaring SED using MJD 56909.8–56922.2. Thus the active phase overlaps the IceCube window by at most ~23 days (MJD 56937.81–56960), and if the fitted sub-phase is meant, it ends before the window begins. The quiescent-state fit for MJD 56949–57059 gives only Nνµ = 0.13 over 158 days. A time-weighted estimate using the model's own fluxes is N ≈ 10.85 × (23/158) + 0.13 × (135/158) ≈ 1.69 events, or roughly 0.13 if the sub-phase has zero overlap. The paper never applies this weighting; the Discussion sentence claiming '13 neutrino events ... during its first active phase' conflates the active duration with the 158-day IceCube box. Since the 10.85-vs-13 match is the sole basis for the paper's new claim that one pp mechanism explains all three IceCube associations, that central claim is unsupported by the calculation as written.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper applies a proton-blazar model, in which shock-accelerated protons interact with cold protons supplied by charge neutrality in the jet, to three IceCube-associated blazars: TXS 0506+056, PKS 0502+049, and GB6 J1040+0617. For each source the authors fit the multi-wavelength SED with a one-zone model including synchrotron, inverse Compton, pp gamma-ray production with internal gamma-gamma absorption, and electromagnetic cascades, and they compute expected IceCube muon-neutrino counts via Eq. (11). The central new claim is that the same pp mechanism can explain the 2014-2015 IceCube flare of 13 +/- 5 muon neutrinos from the direction of TXS 0506+056/PKS 0502+049: for PKS 0502+049 the model yields N_mu = 10.85 events (alpha_p = -2.1) in the 158-day window, or 12.7 muon-like events after including tau-neutrino-induced muons.","tokens_in":19030,"tokens_out":6372,"duration_ms":66947,"significance":"If the central claim were correct, the paper would provide a single hadronic mechanism (pp interactions with cold jet protons) that consistently describes the SEDs and neutrino counts of all three IceCube blazar associations, including the 2014-2015 flare that is difficult for p-gamma and one-zone leptohadronic models. The authors make useful concrete steps: the model parameters are tabulated in Table I, the neutrino count is computed from the stated muon-neutrino flux using the IceCube effective area, and the SED fits include EBL absorption and cascade emission. The modeling of TXS 0506+056 and GB6 J1040+0617 is broadly consistent with existing hadronic-model practice. However, the paper's distinctive result, the explanation of the 13-event 2014-2015 flare from PKS 0502+049, rests on a time-integration error: the flaring-state neutrino rate is applied to the full 158-day IceCube window even though the model's own active phase overlaps only about 23 days of that window. Once the actual overlap is used, the predicted number drops to roughly 1.7 events, so the claimed match with 13 +/- 5 is not supported.","major_comments":[{"comment":"The expected count N_nu_mu = 10.85 for PKS 0502+049 is computed by integrating the flaring-state neutrino flux over tau = 158 days, the full IceCube box window MJD 56937.81 to 57096.21. But the same section states that the first active phase of PKS 0502+049 is MJD 56860-56960, and the Fig. 4 caption fits the flaring SED to MJD 56909.8-56922.2. The overlap with the IceCube window is therefore at most about 23 days (MJD 56937.81 to 56960), and if only the fitted sub-phase is meant, it ends before the IceCube window begins. The quiescent state fitted over MJD 56949-57059 yields only 0.13 events per 158 days. Time-weighting the model's own states gives approximately N = 10.85*(23/158) + 0.13*(135/158) = 1.69 events, or essentially 0.13 events if the fitted sub-phase has zero overlap. The Discussion sentence claiming that the blazar can 'effectively contribute 13 neutrino events ... in 158-days during its first active phase' conflates the active duration with the IceCube window. Since the 10.85-versus-13 match is the sole basis for the paper's new claim that a single pp mechanism explains the 2014-2015 flare, that central claim is unsupported by the calculation as written.","section":"Sec. IV C, Eq. (11), Table I, Fig. 4, Sec. V"},{"comment":"The total jet power found for PKS 0502+049 is L_jet = 8.3 x 10^48 erg/s, which the authors themselves state is about 84 times the Eddington luminosity of 9.8 x 10^46 erg/s. Earlier in Sec. IV A the paper justifies super-Eddington jet power by saying the jet power may exceed Eddington 'within a factor of ten,' but 84 is far outside that range. This energy-budget tension is not discussed for PKS 0502+049, even though the paper criticizes other hadronic models for requiring excessive jet powers. A load-bearing physical-consistency claim of the model therefore needs quantitative justification, such as a time-limited flare energetics argument or a different black-hole mass estimate, rather than an unsupported factor-of-ten remark.","section":"Sec. IV C, Table I"}],"minor_comments":[{"comment":"The text defines the first active phase as MJD 56860-56960, while the Fig. 4 caption fits the flaring SED using MJD 56909.8-56922.2; these intervals should be reconciled because the overlap with the IceCube window, and hence the predicted neutrino count, depends on which interval is meant.","section":"Sec. IV C and Fig. 4"},{"comment":"The phrase 'can effectively contribute 13 neutrino events' should be stated as 'up to about 13 muon-like events for alpha_p = -2.1' and should include the IceCube uncertainty (13 +/- 5) when comparing with the observed flare, since the model's quoted 10.85 or 12.7 does not by itself reproduce 13 exactly.","section":"Sec. V"},{"comment":"The statement that the second active phase of PKS 0502+049 (MJD 57010-57120) is leptonic in origin is initially hedged ('may also be originated in leptonic mechanism as suggested by Sahakyan (2019)') but later asserted as fact; this assumption should be clearly flagged, because the second active phase overlaps a large portion of the IceCube window and would contribute neutrinos if it were hadronic.","section":"Sec. IV C"},{"comment":"The X-ray data used for GB6 J1040+0617 are non-contemporaneous with the gamma-ray/neutrino flare (2003 and 2007-2011 versus 2014-2015), as noted only in the figure caption; this caveat should appear in the main text because it affects the interpretation of the SED fit.","section":"Sec. IV A"},{"comment":"The spelling 'Klein-Nishima' should be 'Klein-Nishina' (the text also contains 'Kllein-Nishima'), and the sentence 'we did not considered' should read 'we did not consider'.","section":"Sec. IV A and IV B"}],"recommendation":"reject","confidential_remarks":"The paper's headline result, the explanation of the 2014-2015 IceCube neutrino flare from PKS 0502+049, is undermined by a straightforward time-integration error: the fitted flaring state lasts only about 23 days inside the 158-day IceCube window, and time-weighting the model's own flaring and quiescent predictions yields roughly 1.7 expected events, not 10.85 or 13. This is not a presentation issue but a load-bearing error in the central claim, and it cannot be repaired by a minor revision without changing the main conclusion. I recommend rejection."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The thing to know: the paper's only new high-impact claim collapses under a timing check. The SED-fitting parts are decent, but the PKS 0502+049 explanation of IceCube's 13-event 2014-2015 flare computes 10.85 events over the full 158-day window while the model's own flaring state overlaps that window by roughly three weeks.\n\nWhat's genuinely new: the proton blazar model from Banik and Bhadra 2019 is extended to GB6 J1040+0617 and to PKS 0502+049 as the likely source of the 2014-2015 neutrino flare. The GB6 treatment is a legitimate application; with alpha_p=-2.1 it gives 0.52 expected muon neutrinos, consistent with IceCube-141209A. The TXS 2017 fit is also reasonable, giving 0.74 events for IceCube-170922A. The model itself is worth taking seriously: cold protons required by charge neutrality supply the pp target, which sidesteps the missing BLR problem in the jet-cloud scenario. The parameters are laid out in enough detail that the calculation is reproducible in principle.\n\nThe soft spot is load-bearing. In Sec. IV C, the 10.85-event number comes from Eq. (11) with tau = 158 days, using the flaring-state SED parameters. But the model's own first active phase for PKS 0502+049 is MJD 56860-56960, and the fitted flaring sub-phase is MJD 56909.8-56922.2. The IceCube window is MJD 56937.81-57096.21. So the flaring state overlaps the window by at most 23 days, and the sub-phase actually ends before the window starts. The quiescent fit gives 0.13 events over 158 days. Time-weighting the model's own numbers gives about 1.7 expected events, not 10.85. The Discussion sentence saying the source can contribute 13 events 'during its first active phase' conflates the active duration with the IceCube box. That is the central new result, and as written it does not hold up.\n\nOther concerns are smaller. The 1.2-degree offset between PKS 0502+049 and TXS 0506+056 is asserted as positionally consistent without quantitative angular-error justification. The jet power in the PKS flaring state is 84 times Eddington, which is high but not unprecedented in the literature. The event counts are consistency checks rather than fits, so the circularity critique applies, but that is expected for a model-consistency study and is not by itself a flaw. The timing problem is.\n\nWho is this for: people working on hadronic blazar models and multi-messenger associations. It deserves a serious referee because the framework is plausible and the GB6 extension is useful, but the PKS 0502+049 claim needs major revision or removal. If the authors redo the integration with proper time weighting, the paper could be a solid consistency study. I would not cite it in its current form.","headline":"A plausible model-consistency paper whose central new claim—PKS 0502+049 explaining the 13-event IceCube flare—is undermined by the paper's own timing: the flaring state overlaps the 158-day window for only ~23 days.","tokens_in":19686,"tokens_out":3331,"would_cite":false,"duration_ms":33247,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["96.50.S-","98.70.Rz","98.70.Sa"],"model":"deepseek-v4-flash","headline":"Cold protons inside blazar jets can explain the neutrino and gamma-ray observations from three blazars","keywords":["cosmic rays","neutrinos","blazars","hadronic pp interactions","proton blazar model","charge neutrality","gamma-ray flares","multi-messenger astronomy"],"falsifier":"A time-resolved analysis of the 158-day neutrino window that places the 2014-2015 muon-neutrino events outside the two fitted flaring periods of PKS 0502+049 (MJD 56860-56960 and MJD 57010-57120), or that assigns the excess to TXS 0506+056, would settle the claim.","tokens_in":18370,"feed_emoji":"🧊","tokens_out":12281,"duration_ms":112492,"temperature":0.7,"pith_summary":"This paper tries to establish a single hadronic origin for the high-energy neutrinos and gamma-ray flares that a South Pole neutrino observatory has associated with three blazars. It argues that the jets themselves contain enough non-relativistic protons, required simply by charge neutrality, to serve as targets for proton-proton collisions, so external gas clouds are not needed. If the argument is right, the same mechanism explains the 2014-2015 flare of 13 muon-neutrino events, the single 2017 event, and the single event from GB6 J1040+0617, while also reproducing each source's broadband spectrum. That would resolve the long-standing tension that the neutrino counts seemed too high for standard photohadronic models.","feed_headline":"Blazar's own cold protons can explain the 13-neutrino flare","feed_subtitle":"Proton collisions inside the jet reproduce the gamma-ray spectra and neutrino counts for all three blazars.","key_machinery":"The load-bearing mechanism is the cold-proton target density $n_{\\rm H} = n'_e - n'_p$ fixed by charge neutrality in the jet. With a low electron acceleration efficiency of $\\chi_e \\approx 10^{-3}$, this yields target densities of roughly $10^{5}$-$10^{6}$ cm$^{-3}$ in the modeled emission regions. Shock-accelerated protons follow a power-law distribution $N'_p \\propto \\gamma_p'^{-\\alpha_p}$, and their collisions with the cold protons produce pions; neutral pions decay to gamma-rays and charged pions to neutrinos. The gamma-ray output is then attenuated by internal $\\gamma\\gamma$ absorption and reprocessed by electromagnetic cascades, while the neutrino flux is converted to an expected detector event count using the effective area and neutrino oscillation probabilities.","core_discovery":"The paper's central claim is that inelastic proton-proton collisions between shock-accelerated protons and the non-relativistic cold protons that must be present in a charge-neutral jet can simultaneously describe the observed spectral energy distributions and neutrino counts for TXS 0506+056, PKS 0502+049, and GB6 J1040+0617. For PKS 0502+049 during its first active phase, the model gives $N_{\\nu_\\mu} \\approx 10.85$ events with proton spectral index $\\alpha_p = -2.1$ over the 158-day window, consistent with the observed $13 \\pm 5$; with $\\alpha_p = -2.2$ it gives 5.2 events. The same model yields 0.74 events for TXS 0506+056 in its 2017 flaring state, 0.52 for GB6 J1040+0617, and only 0.13-0.19 for the quiescent states, so the authors conclude that PKS 0502+049, not TXS 0506+056, is the main source of the 2014-2015 flare.","pith_inferences":["Extending beyond the paper, a charge-neutral jet should contain these cold-proton targets in every blazar, so stacking many non-flaring blazars in neutrino telescopes might reveal a low-level neutrino flux even when no gamma-ray flare is present; this is testable with archival data.","The paper's PKS 0502+049 event count assumes the fitted flaring-state parameters apply across the entire 158-day window, although the fitted first active phase overlaps it by only about 23 days; a time-dependent calculation with the actual exposure history would show how sensitive the 10.85-event number is to that assumption.","The same mechanism could apply to other BL Lac objects that lack broadline emission, predicting correlated TeV gamma-ray and neutrino emission from a larger population than the three sources studied here.","If the second PKS 0502+049 active phase is genuinely leptonic, as the paper assumes, then gamma-ray flares without neutrino counterparts should be common; combining temporal gamma-ray and neutrino data over many flares would test that division."],"forward_implications":["The 2014-2015 neutrino flare can be explained without requiring TXS 0506+056 to be active; the nearby PKS 0502+049 supplies the events during its flaring phase.","The high-energy gamma-ray humps of these blazars can be hadronic in origin, produced inside the jet itself, so neither external photon fields nor broadline-region clouds are required.","The maximum accelerated-proton energies inferred in the observer frame are about $3.5$-$4.5\\times10^{17}$ eV, roughly an order of magnitude below the cosmic-ray ankle.","The model predicts a neutrino flavour ratio at Earth close to $1:1:1$, consistent with standard three-flavour oscillations from a source ratio of $1:2:0$."],"supporting_citations":[{"why":"Supplies the proton-blazar framework, including the charge-neutrality cold-proton target and the flux calculation method used for all three sources.","marker":"[17]"},{"why":"Provides the observed neutrino event counts and time windows, including the 13-event 2014-2015 flare and the 2017 event, that the model must reproduce.","marker":"[8]"},{"why":"Identifies PKS 0502+049 as the gamma-ray flaring blazar near TXS 0506+056 during the 2014-2015 neutrino window.","marker":"[14]"},{"why":"Documents that standard lepto-hadronic models cannot reproduce the 13-event flare, motivating a pp-based alternative.","marker":"[25]"},{"why":"Represents the jet-cloud pp scenario whose broadline-region clouds are questioned by the absence of broadline emission.","marker":"[20]"},{"why":"Reports the GB6 J1040+0617 neutrino association and the multiwavelength state used for that source's SED fit.","marker":"[16]"},{"why":"Supports treating the second PKS 0502+049 active phase as leptonic, so only the first phase contributes neutrinos.","marker":"[60]"},{"why":"Provides the detector effective area used to convert predicted neutrino fluxes into expected muon-neutrino event counts.","marker":"[53]"},{"why":"Supplies the self-consistent electromagnetic cascade formalism used to compute secondary gamma-ray emission.","marker":"[31]"},{"why":"Gives the pion-production emissivities for proton-proton collisions used to derive gamma-ray and neutrino spectra.","marker":"[43]"}],"fun_headline_variants":["Cold protons in blazar jets explain the 13-neutrino burst","Blazar's internal cold protons reproduce 13-neutrino flare","Charged jet protons solve blazar neutrino mystery","Neutrino flare from blazar's own cold protons","Proton-blazar model nails the 13-neutrino event"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing assumption is that the 2014-2015 neutrino flare came from PKS 0502+049 and that its flaring-state proton output persisted across the whole 158-day window, even though the fitted first active phase overlaps only about 23 days of that window.","fun_headline_variants_meta":{"raw":{"variants":["Cold protons in blazar jets explain the 13-neutrino burst","Blazar's internal cold protons reproduce 13-neutrino flare","Charged jet protons solve blazar neutrino mystery","Neutrino flare from blazar's own cold protons","Proton-blazar model nails the 13-neutrino event"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000195,"raw_usage":{"total_tokens":1400,"prompt_tokens":1031,"completion_tokens":369,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":647,"completion_tokens_details":{"reasoning_tokens":282}},"tokens_in":647,"tokens_out":369,"duration_ms":4261,"temperature":1.0,"reasoning_tokens":282,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T05:06:19.689053+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A time-resolved analysis of the 158-day neutrino window that places the 2014-2015 muon-neutrino events outside the two fitted flaring periods of PKS 0502+049 (MJD 56860-56960 and MJD 57010-57120), or that assigns the excess to TXS 0506+056, would settle the claim.","supporting_citations":[{"cited_title":"1 × 1041 1","cited_arxiv_id":null,"evidence_quote":"Supplies the proton-blazar framework, including the charge-neutrality cold-proton target and the flux calculation method used for all three sources."},{"cited_title":"Note that XMM-Newton and Swift-XRT data are not mutu- ally consistent which may be due to dynamical behavior of the source","cited_arxiv_id":null,"evidence_quote":"Provides the observed neutrino event counts and time windows, including the 13-event 2014-2015 flare and the 2017 event, that the model must reproduce."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Identifies PKS 0502+049 as the gamma-ray flaring blazar near TXS 0506+056 during the 2014-2015 neutrino window."},{"cited_title":"Rodrigues, S","cited_arxiv_id":null,"evidence_quote":"Documents that standard lepto-hadronic models cannot reproduce the 13-event flare, motivating a pp-based alternative."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supports treating the second PKS 0502+049 active phase as leptonic, so only the first phase contributes neutrinos."},{"cited_title":"Albert et al., Mon","cited_arxiv_id":null,"evidence_quote":"Provides the detector effective area used to convert predicted neutrino fluxes into expected muon-neutrino event counts."},{"cited_title":"Keivani et al., Astrophys.J","cited_arxiv_id":null,"evidence_quote":"Supplies the self-consistent electromagnetic cascade formalism used to compute secondary gamma-ray emission."},{"cited_title":"Ghisellini, F","cited_arxiv_id":null,"evidence_quote":"Gives the pion-production emissivities for proton-proton collisions used to derive gamma-ray and neutrino spectra."}],"review_version":1}