{"id":"462c32f8-8d81-4f49-8fa3-3869ce5286a1","arxiv_id":"1908.05450","paper_version":1,"verdict":"CONDITIONAL","confidence":"LOW","novelty_score":4.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"The partially built Baikal-GVD telescope searched for neutrinos from GW170817 and TXS 0506+056, found none, and set upper limits on the GW170817 neutrino fluence.","lead":"The Baikal-GVD neutrino telescope searched for neutrinos from a gravitational wave event and a blazar flare and found no matches. These first multi-messenger results set upper limits on the neutrino fluence from the neutron star merger GW170817.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 90% C.L. fluence limits depend on effective volumes from Ref. [5]; the paper's stated time-window-dependent cuts may not match that calculation, leaving the central quantitative claim unverified.","rationale":"The reader's weakest assumption correctly identifies that the limit derivation is deferred to Ref. [5] and that the E^-2 and equal-flavor assumptions are load-bearing. I agree that this makes the quantitative result conditional. However, I would sharpen the concern: the E^-2 and equal-flavor assumptions are explicitly stated and are standard conventions, so they are not the most fragile part. The more acute issue is the internal statement that cuts vary with time window; this implies the effective volume used in the limit calculation must also vary, but the paper does not show how Ref. [5] maps the cuts to effective volumes for each window. Without that mapping, the 90% C.L. limits could be based on exposures that do not match the actual event selection, making the reported limits unreliable. The non-detection of events is credible because the search has at least some sensitivity, but the central claim as phrased by the reader ('upper limits were established') cannot be fully verified from this paper alone. A conditional verdict is appropriate. I would not escalate to rejection because there is no evidence of an internal inconsistency; the calculation may well be correct in Ref. [5]. The concrete test of re-implementing the limit from the stated cuts and source geometry would settle the concern.","tokens_in":3408,"tokens_out":5974,"duration_ms":60780,"concrete_test":"Obtain Ref. [5] (Avrorin et al., JETP Lett. 108, 787, 2018) and independently re-implement the upper-limit calculation for the two operational GVD clusters: compute the time-integrated exposure for the ±500 s prompt window and the 14-day delayed window using (a) the effective volume for cascades as a function of energy and zenith angle (with Earth absorption for the 93.3° source direction), and (b) the time-window-dependent cuts described in Section 1. Then derive the 90% C.L. fluence limits per energy decade for an E^-2 spectrum with equal flavor partition. Compare the resulting limits to Fig. 2 (left). If the recomputed limits differ from the published values by more than the statistical uncertainty from zero events, the paper's central claim is not supported without including that derivation.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper's central quantitative claim is that 90% C.L. upper limits on the neutrino fluence from GW170817 were established. The non-detection itself is plausible, but the limit values are not derived in the text; they are deferred to Ref. [5]. A specific internal statement raises a concern: Section 1 says 'The values of cuts are slightly varied in dependence on time windows in the follow up analysis, so that they are weaker for shorter times.' This means the selection efficiency and effective volume are not fixed across the ±500 s prompt window and the 14-day delayed window. If Ref. [5] computes the limit using a single effective volume or a different set of cuts, the zero events observed would translate into different fluence limits than those reported. Additionally, the source zenith is 93.3°, i.e., slightly below the horizon; the cascade effective volume at that direction is affected by Earth absorption and must be modeled as a function of energy. The paper does not state the angular search radius used for 'spatially coincident' nor the energy threshold applied to the GW search, so the reader cannot verify that the non-detection is meaningful. These are not merely editorial omissions: if the referenced calculation used a different exposure, the 90% C.L. upper limits could be off by a factor that changes the physical interpretation (e.g., whether the limits exclude realistic neutron-star merger models).","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper, a proceedings contribution from the 36th ICRC, reports the first multi-messenger follow-up searches performed with the Baikal-GVD neutrino telescope while it was under construction. Using two operating clusters in 2017 and the cascade detection mode, the authors searched for high-energy neutrinos in coincidence with GW170817/GRB170817A and with the blazar TXS 0506+056 (IC170922). No neutrino candidates were found that are spatially and temporally coincident with either source. Assuming an E^-2 neutrino spectrum and equal flavor partition, the paper presents 90% confidence-level upper limits on the neutrino fluence from GW170817 for both the ±500 s prompt window and a 14-day delayed window. The paper also briefly describes the status of the Baikal-GVD alert system and a follow-up of ANTARES neutrino alerts, again with no observed coincidences.","tokens_in":3609,"tokens_out":4968,"duration_ms":44933,"significance":"If the reported limits are correct, this is a valuable early demonstration that a partial neutrino detector under construction can already contribute to multi-messenger astronomy, placing meaningful constraints on high-energy neutrino emission from a binary neutron star merger. The non-detection itself is credible, and the paper explicitly states the spectral and flavor assumptions used in the interpretation. The paper is also transparent about its preliminary nature and about the fact that many details are deferred to a companion paper. However, the central quantitative result — the 90% C.L. fluence limits — is not derived in this manuscript; the reader is referred to Ref. [5] without being given the exposure, effective volume, search cone, or energy threshold needed to verify the calculation. In addition, the paper's own statement that the event selection cuts vary with the time window introduces a potential inconsistency in how the prompt and delayed limits are computed. These gaps make the paper more a status report than a self-contained measurement, but the underlying approach is sound and the issues are addressable in a revision.","major_comments":[{"comment":"The 90% C.L. fluence limits shown in Fig. 2 (left) are asserted without derivation. The text only states that \"more details of analysis are presented in Ref. [5]\" and that \"assuming an E^-2 spectral behavior and equal fluence in neutrino flavors, upper limits at 90% c.l. have been derived.\" Since these limits are the central quantitative claim of the paper, the manuscript should at least specify the exposure (number of clusters, livetime), the search cone radius, the energy threshold, and the effective volume or acceptance used, or it should reproduce the calculation in an appendix. Without this information, the reader cannot verify that the limits correspond to the analysis described in the text.","section":"Section 2"},{"comment":"Section 1 states that \"the values of cuts are slightly varied in dependence on time windows in the follow up analysis, so that they are weaker for shorter times.\" Section 2 then presents separate limits for the prompt (±500 s) and delayed (14-day) emission windows. Because the effective volume of the detector depends on the event selection cuts, the two limits must have been computed with different selection efficiencies. The paper does not state how these time-dependent cuts enter the limit calculation, nor whether Ref. [5] used the same varying cuts. Without this information, the two limit curves in Fig. 2 (left) cannot be interpreted consistently, and the normalization of both could be wrong if a single effective volume was used.","section":"Sections 1 and 2"},{"comment":"The paper reports no systematic uncertainties on the fluence limits. The source NGC 4993 was at a zenith angle of 93.3°, i.e., slightly below the horizon for Baikal-GVD, so the cascade effective volume is affected by energy-dependent Earth absorption and by the assumed neutrino cross-section. In addition, uncertainties in the energy scale, angular resolution, and event selection efficiency could shift the limits by an amount that is not quantified. Since the limits are intended for comparison with theoretical models of neutron-star merger neutrino emission, the paper should include at least a discussion of the dominant systematic errors and their effect on the 90% C.L. limits.","section":"Section 2"},{"comment":"The search for neutrino events \"associated with these sources\" over a fixed direction is not fully specified: the paper does not state the angular acceptance radius used to define spatial coincidence, nor the energy range over which the limits apply. Given the quoted median cascade angular resolution of about 4.5°, the meaning of \"no events spatially coincident\" is ambiguous. The paper should state the search cone (for example the 90% angular containment radius) and the energy range for the GW170817 search so that the non-detection can be properly interpreted.","section":"Section 2"}],"minor_comments":[{"comment":"The text reads \"TMV A implementation\"; this should be \"TMVA\" (Toolkit for Multivariate Analysis).","section":"Section 1"},{"comment":"The phrase \"an E −2.46 spectrum\" should be typeset as a power law, e.g., E^{-2.46}, to avoid ambiguity.","section":"Section 1"},{"comment":"The naming of the blazar is inconsistent: the text uses both \"IC170922\" and \"IC170922A\", as well as \"TX-0506+056\" and \"TXS 0506+056\"; a single consistent nomenclature should be adopted.","section":"Section 2"},{"comment":"Figure 2 (right) is described only as a \"distribution of number of events in a time window of ±1 hour\"; the caption should define the quantity on the horizontal axis and the meaning of the plotted histogram.","section":"Section 2"},{"comment":"The phrase \"half-open cone of 10°\" and \"half-open cone 5°\" is not defined; the authors should specify that the cone is defined by an angular radius around the alert direction and state the exact convention.","section":"Section 3"},{"comment":"The sentence \"In best case of happened coincidence within time window of ±1 day...\" is awkwardly worded and should be rewritten for clarity.","section":"Section 3"}],"recommendation":"major_revision","confidential_remarks":"This manuscript is a conference proceedings paper, and the level of detail is typical for an ICRC contribution. For a journal-style publication, however, the central quantitative claim (the fluence limits) is deferred to Ref. [5], and the paper does not provide enough information to verify the calculation. The internal inconsistency regarding time-dependent cuts strengthens the case that this is a load-bearing issue, not a mere editorial preference. I do not see any evidence of circular reasoning or overreach; the paper reports an observational search with clearly stated assumptions. I recommend major revision rather than rejection because the underlying non-detection and upper-limit approach are sound and the missing material can be supplied within the manuscript's scope."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Quick take: this is a short ICRC proceedings paper from the Baikal-GVD collaboration. The genuinely new thing is that two clusters of a partially built deep-water neutrino telescope looked for neutrinos from GW170817 and IC170922 and found none; the paper then quotes 90% C.L. limits on the GW170817 neutrino fluence. The non-detection is credible and the search design is reasonable. The soft spot is that the quantitative limit calculation is not in this paper—it is deferred to Ref. [5]—and the paper itself says the analysis cuts vary with time window. That makes the quoted limits unverifiable from the text alone.\n\nWhat's good: they state the source zenith angle (93.3°) for GW170817, so the issue of Earth absorption is on the table. They give angular and energy resolution for the cascade channel and describe the quality cuts. They report no coincident events in prompt (±500 s) and 14-day delayed windows, and no correlations with ANTARES alerts over six months, with a background estimate. For a proceedings, this is an honest status report.\n\nThe real concern: the fluence limits are the only quantitative output, and they are asserted, not derived. The stress-test note is right to point out that 'the values of cuts are slightly varied... so that they are weaker for shorter times'—if the effective volume used in Ref. [5] doesn't match the cuts applied here, the limits could shift. Also, the angular search radius and energy threshold for the GW170817 search are not stated, so a reader can't tell what 'spatially coincident' meant. These omissions are real but not fatal: the non-detection stands, and the limits are almost certainly weaker than IceCube's or ANTARES's anyway, so the physical interpretation wouldn't change dramatically. Still, if this paper were submitted as a standalone research letter, a referee should ask for the limit derivation to be shown or the reference verified.\n\nCitation behavior is fine: the references point to the original GW170817 detection, the IceCube TXS paper, and the collaboration's own detector papers; no red flags.\n\nWho it's for: anyone tracking the buildout of Baikal-GVD or compiling all neutrino limits on GW170817. Most readers will skip it; it's a data point, not a method. I'd send it to peer review if it came in as a letter, because the first result from a new detector deserves a check that the quoted limits match the actual exposure. For an ICRC proceeding, it's fine as is. Verdict: worth a referee, but I wouldn't cite it as a primary source for the limit—cite Ref. [5] for that.","headline":"Baikal-GVD's first multi-messenger search: a credible non-detection, but the fluence limits rest on a referenced calculation that this paper itself does not make checkable.","tokens_in":4547,"tokens_out":3356,"would_cite":false,"duration_ms":32063,"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":"The Baikal-GVD telescope, with only two clusters operational in 2017, reports no neutrinos coincident with GW170817 and sets 90% C.L. upper limits on the neutrino fluence.","keywords":["Baikal-GVD","neutrino telescope","multi-messenger astronomy","gravitational waves","GW170817","neutrino fluence","upper limits","cascade detection"],"falsifier":"One concrete check is to rerun the cascade reconstruction on the archived 2017 Baikal-GVD data in the $\\pm 500$ second and 14-day windows around GW170817 with the same cuts and see whether any event with reconstructed energy above 100 TeV falls inside the spatial selection; any such event would contradict the non-detection claim. A second check is to recompute the expected atmospheric background in the 74 to 150 degree zenith band used for the delayed search with the detector simulation: if the background is substantially larger than the assumed value, the 90% C.L. fluence limits would be understated.","tokens_in":3191,"feed_emoji":"🔭","tokens_out":10809,"duration_ms":98742,"temperature":0.7,"pith_summary":"The paper reports the first multi-messenger follow-up performed with the partially built Baikal-GVD neutrino telescope, which records Cherenkov light from high-energy neutrino interactions in Lake Baikal. Using the cascade detection mode of the two clusters that were taking data in 2017, the collaboration searched for neutrinos coincident in time and direction with GW170817/GRB170817A and with the blazar alert IC170922. No candidate neutrino events were found in either search. For GW170817, where the source NGC 4993 lay at zenith angle 93.3 degrees and thus slightly below the horizon, the non-detection was converted into 90% confidence upper limits on the high-energy neutrino fluence, assuming an $E^{-2}$ spectrum with equal fluence in all three neutrino flavors. The results show that even an early-stage detector can already contribute to multi-messenger astronomy, and the paper also describes the online alert system being built for real-time follow-up.","feed_headline":"Baikal-GVD finds no neutrinos from GW170817, sets fluence limits","feed_subtitle":"A two-cluster detector already constrains high-energy neutrino emission from a neutron-star merger.","key_machinery":"The load-bearing mechanism is the cascade detection mode of Baikal-GVD: Cherenkov light from the particle cascades produced by high-energy neutrino interactions in water is reconstructed into direction and energy. The median angular resolution is about 4.5 degrees and the energy resolution averaged over an $E^{-2}$ spectrum of electron neutrinos is about 30%, with roughly 90% of reconstructed cascade events falling between 5 TeV and 10 PeV. Around this reconstruction sits an alert-search strategy that fixes a direction and time window for each external trigger, applies cascade-quality cuts, and searches both prompt and delayed windows. That procedure is what turns the recorded hits into a null result, and the null result is what is then converted into the quoted fluence limits.","core_discovery":"The central claim is that Baikal-GVD, with only two of its planned clusters operational during 2017, detected no neutrinos coincident with GW170817/GRB170817A and therefore established 90% confidence upper limits on the high-energy neutrino fluence from that neutron-star merger. In cascade mode the source lay slightly below the horizon at the detector (zenith angle 93.3 degrees), and no events were found either in the prompt $\\pm 500$ second window or in a delayed window of 14 days, restricted to the zenith range from 74 to 150 degrees. The same analysis applied to the blazar TXS 0506+056 in the IC170922 follow-up found no coincident neutrinos in $\\pm 1$ hour and $\\pm 1$ day windows. The fluence limits assume an $E^{-2}$ neutrino spectrum and equal fluence in all three neutrino flavors, with the details of the limit calculation deferred to reference [5].","pith_inferences":["The published fluence limits are benchmark bounds rather than model-independent exclusions: if the true neutrino spectrum is softer than $E^{-2}$ or the flavors are not equally populated, the 90% C.L. limits would shift outside the quoted bands.","The paper's own background estimates suggest that at the three-cluster scale a handful of cascade events near an alert direction remains consistent with atmospheric muons, so individual coincidences should be treated as candidate associations until the array grows and the live time lengthens.","A combined analysis of null results from neutrino telescopes with complementary sky coverage, Baikal-GVD among them, would tighten the joint upper limits on high-energy neutrino emission from neutron-star mergers without waiting for a single detection.","If a future binary neutron-star merger is observed while the source is above the Baikal-GVD horizon, the same cascade search would have substantially better sensitivity, because the GW170817 search was handicapped by a source slightly below the horizon."],"forward_implications":["With two clusters operating in 2017, the cascade channel is already sensitive enough to place 90% C.L. upper limits on the neutrino fluence of a gravitational-wave source.","The lack of coincident neutrinos in the 14-day delayed window around GW170817 extends the constraint beyond the prompt emission phase.","The same cascade search found no neutrinos from the blazar TXS 0506+056 in either a one-hour or a one-day window, adding an independent non-detection to the IC170922 picture.","Following external neutrino alerts, no time-direction correlations were found in six months of observations, with an estimated atmospheric background toward a given direction of about 1.75 events per day inside a 10-degree cone and 0.5 events per day inside a 5-degree cone for three clusters.","With the array growing and an online alert system under development, the same selection logic is intended to run in real time and issue alerts to other observatories."],"supporting_citations":[{"why":"Supplies the gravitational-wave event GW170817 and its source NGC 4993 that define the target direction and time for the neutrino search.","marker":"[1]"},{"why":"Provides the blazar alert IC170922 that serves as the second external target for the coincidence search.","marker":"[2]"},{"why":"Establishes the cascade event reconstruction and selection used to identify neutrino candidates in Baikal-GVD.","marker":"[3]"},{"why":"Carries the derivation of the 90% C.L. fluence upper limits quoted for GW170817 on the basis of the null result.","marker":"[5]"}],"fun_headline_variants":["Baikal-GVD sees no neutrinos from GW170817, sets limits","Two-cluster Baikal-GVD already constrains GW170817 neutrinos","No neutrinos from GW170817: Baikal-GVD sets first limits","Baikal-GVD's first multi-messenger search: no GW170817 neutrinos","Baikal-GVD upper limits from GW170817 neutrino search"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The upper limits assume the neutrino flux falls as $E^{-2}$, that all three neutrino flavors contribute equally, and that the detector-response model from reference [5] is correct; if any of these assumptions fails, the quoted 90% C.L. limits would change.","fun_headline_variants_meta":{"raw":{"variants":["Baikal-GVD sees no neutrinos from GW170817, sets limits","Two-cluster Baikal-GVD already constrains GW170817 neutrinos","No neutrinos from GW170817: Baikal-GVD sets first limits","Baikal-GVD's first multi-messenger search: no GW170817 neutrinos","Baikal-GVD upper limits from GW170817 neutrino search"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001072,"raw_usage":{"total_tokens":4477,"prompt_tokens":918,"completion_tokens":3559,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":534,"completion_tokens_details":{"reasoning_tokens":3458}},"tokens_in":534,"tokens_out":3559,"duration_ms":24958,"temperature":1.0,"reasoning_tokens":3458,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T13:12:58.018626+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"One concrete check is to rerun the cascade reconstruction on the archived 2017 Baikal-GVD data in the $\\pm 500$ second and 14-day windows around GW170817 with the same cuts and see whether any event with reconstructed energy above 100 TeV falls inside the spatial selection; any such event would contradict the non-detection claim. A second check is to recompute the expected atmospheric background in the 74 to 150 degree zenith band used for the delayed search with the detector simulation: if the background is substantially larger than the assumed value, the 90% C.L. fluence limits would be understated.","supporting_citations":[{"cited_title":"Abbott et al., Phys","cited_arxiv_id":null,"evidence_quote":"Supplies the gravitational-wave event GW170817 and its source NGC 4993 that define the target direction and time for the neutrino search."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides the blazar alert IC170922 that serves as the second external target for the coincidence search."},{"cited_title":"Dvornický et al., Baikal Coll., these proceedings, Search for cascade events with Baikal-GVD","cited_arxiv_id":null,"evidence_quote":"Establishes the cascade event reconstruction and selection used to identify neutrino candidates in Baikal-GVD."},{"cited_title":"Avrorin et al., JETP Lett","cited_arxiv_id":null,"evidence_quote":"Carries the derivation of the 90% C.L. fluence upper limits quoted for GW170817 on the basis of the null result."}],"review_version":1}