{"id":"e1c9c5da-0031-4658-852c-84cce57bb537","arxiv_id":"2606.12613","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":7.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"First spectrotomographic weak lensing measurements on A1767 and A2065 with HSC data yield shear signals consistent with dynamical masses.","lead":"The paper reports spectroscopic tomographic weak lensing detections for galaxy clusters A1767 and A2065 using Subaru/HSC imaging and spectroscopic redshifts, achieving 3.1σ and 3.5σ signals. This approach could enable more reliable cluster mass measurements by avoiding photometric redshift uncertainties for future surveys.","discovery_kind":"new_application","skeptic_critique":{"model":"grok-4.3","headline":"Subtle shear systematics for bright spec-z galaxies (flagged via A2029) remain unquantified and could shift the reported 3.1–3.5σ detections.","rationale":"The reader's weakest assumption directly matches the paper's own caveat about A2029; the full text does not resolve it with additional validation, so the concern remains load-bearing for the claimed detections and consistency checks.","tokens_in":1780,"tokens_out":320,"duration_ms":8053,"concrete_test":"Recompute the tomographic shear signals for A1767 and A2065 after applying an independent shear catalog (different PSF correction or shape-measurement code) restricted to the same spectroscopic galaxies; if the amplitude changes by >30% or the significance drops below 2σ, the original detections are sensitive to the flagged systematics.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The central claim requires that shear amplitudes measured on the relatively bright spectroscopic background sample are free of the subtle systematics noted in the A2029 DECam comparison. The paper states that measurements use only galaxies with the reported spectroscopic redshifts and that signals scale with source redshift and match caustic masses, but provides no quantitative test (e.g., null tests, alternative PSF models, or magnitude-dependent residuals) showing that the same issues do not affect the HSC data at a level comparable to the reported significance. Because the sample is limited to spectroscopically confirmed objects, any selection- or measurement-induced bias directly propagates into both the detection significance and the redshift-scaling test.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The manuscript presents the first application of spectroscopic tomographic weak lensing (spectrotomography) to clusters A1767 and A2065 using archival Subaru/HSC imaging combined with new spectroscopy. It reports tomographic shear detections at 3.1σ (A1767) and 3.5σ (A2065) based exclusively on galaxies with spectroscopic redshifts, claims consistency of shear amplitudes with independent dynamical (caustic) masses, and notes appropriate scaling with source redshift. The work also compares to a prior A2029 detection and flags potential subtle systematics in shear measurements for relatively bright background galaxies.","tokens_in":1918,"tokens_out":559,"duration_ms":15370,"significance":"If the shear measurements prove robust, the result demonstrates a data-driven method for cluster weak-lensing masses that avoids photometric-redshift contamination and selection biases. The reported consistency with caustic masses and redshift scaling would provide independent validation. With three clusters now measured (including A2029), the technique is positioned for broader use in unbiased mass calibration and potentially for geometric cosmological tests independent of other probes, with direct relevance to Euclid and LSST data.","major_comments":[{"comment":"Abstract and final paragraph: the central claim of 3.1σ and 3.5σ detections rests on the assertion that shear amplitudes for the bright spectroscopic background sample are free of the subtle systematics identified in the A2029 DECam comparison. No quantitative test (null test, PSF-model variation, or magnitude-dependent residual analysis) is presented to show that any such bias is smaller than the reported significance; because the sample is restricted to spectroscopically confirmed objects, any measurement bias directly affects both the detection significance and the redshift-scaling test.","section":"Abstract"},{"comment":"The assumption that spectroscopic redshifts yield negligible cluster-member contamination and no selection-induced bias in the shear sample is load-bearing for the mass-consistency and redshift-scaling statements, yet no explicit contamination fraction, purity estimate, or test against alternative redshift cuts is provided.","section":"Methods (spectroscopic selection)"}],"minor_comments":[{"comment":"The abstract states that signals 'scale appropriately with source redshift' but does not specify the number of tomographic bins or the exact redshift ranges used; adding this detail would clarify the tomographic aspect.","section":"Abstract"},{"comment":"Figure captions and text should explicitly state the magnitude limit and typical S/N of the spectroscopically selected background galaxies to allow readers to assess the relevance of the A2029 systematics warning.","section":null}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for their careful and constructive review of our manuscript. We address the major comments point by point below and will revise the manuscript to incorporate the suggested improvements.","responses":[{"response":"We agree that the absence of explicit quantitative tests for these clusters leaves the robustness of the 3.1σ and 3.5σ claims open to the concern raised. The manuscript already flags potential subtle systematics from the A2029 comparison, but we did not perform the specific null tests, PSF variations, or magnitude-dependent analyses for A1767 and A2065. We will add these tests in the revised manuscript to the extent permitted by the data, along with a clearer discussion of how any residual bias would impact the significance and scaling results.","revision_made":"yes","referee_comment":"[Abstract] Abstract and final paragraph: the central claim of 3.1σ and 3.5σ detections rests on the assertion that shear amplitudes for the bright spectroscopic background sample are free of the subtle systematics identified in the A2029 DECam comparison. No quantitative test (null test, PSF-model variation, or magnitude-dependent residual analysis) is presented to show that any such bias is smaller than the reported significance; because the sample is restricted to spectroscopically confirmed objects, any measurement bias directly affects both the detection significance and the redshift-scaling test."},{"response":"While the use of spectroscopic redshifts provides a clean separation in principle, we acknowledge that the manuscript lacks the explicit quantitative estimates and sensitivity tests requested. We will revise the methods section to include contamination fraction and purity estimates derived from the spectroscopic catalog, as well as tests of the shear signal under alternative redshift cuts, to better support the mass-consistency and scaling claims.","revision_made":"yes","referee_comment":"[Methods (spectroscopic selection)] The assumption that spectroscopic redshifts yield negligible cluster-member contamination and no selection-induced bias in the shear sample is load-bearing for the mass-consistency and redshift-scaling statements, yet no explicit contamination fraction, purity estimate, or test against alternative redshift cuts is provided."}],"tokens_in":1475,"tokens_out":458,"duration_ms":16000,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"This paper reports the first application of spectrotomography to Subaru HSC imaging for A1767 and A2065. They measure tomographic shear signals at 3.1 sigma and 3.5 sigma using only galaxies with new spectroscopic redshifts, and the amplitudes line up with the clusters' caustic dynamical masses while scaling with source redshift.\n\nThe clean separation of background sources via spectroscopy is the real strength. It sidesteps the usual photometric redshift contamination that affects most cluster lensing work. Extending the earlier DECam result on A2029 to HSC data is a straightforward next step, and the redshift-scaling test provides an internal consistency check that is worth having.\n\nThe approach is data-driven and avoids circularity with the mass comparison. The authors are also direct about the remaining question: their A2029 comparison already showed subtle potential systematics in shear measurements on relatively bright background galaxies. This paper uses a comparable sample but does not describe quantitative null tests or residual checks to show those effects stay below the reported significance.\n\nThe work is for people in the cluster weak lensing subfield who are thinking about systematic control for future surveys like Euclid or LSST. It is a modest but honest incremental result rather than a broad advance.\n\nA serious editor should send it to referees. The technique has clear potential, and the paper flags its own open issues without overclaiming.","headline":"The paper delivers the first HSC-based spectrotomography detections at 3.1-3.5 sigma for A1767 and A2065 that match caustic masses, but leaves the bright-galaxy shear systematics flagged in their A2029 work unquantified.","tokens_in":2383,"tokens_out":378,"would_cite":false,"duration_ms":16170,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.3","headline":"Spectroscopic redshifts enable tomographic weak lensing detections in clusters A1767 and A2065 at 3.1 and 3.5 sigma.","keywords":["weak lensing","spectrotomography","galaxy clusters","tomographic shear","spectroscopic redshifts","A1767","A2065"],"falsifier":"A measurement in which the tomographic shear amplitudes fail to match the caustic dynamical masses or do not increase with source redshift would falsify the detection claim.","tokens_in":2697,"feed_emoji":"🔭","tokens_out":615,"duration_ms":30404,"temperature":0.7,"pith_summary":"The paper demonstrates the first use of spectrotomography on archival Subaru/HSC imaging for two galaxy clusters. Spectroscopic redshifts separate background galaxies cleanly from cluster members and suppress systematics that photometric redshifts can introduce. Tomographic shear signals are detected at 3.1 sigma in A1767 and 3.5 sigma in A2065. The measured amplitudes match independent dynamical caustic masses and increase with source redshift as expected. The work positions the method for wider use in unbiased cluster mass calibration and a potential geometric cosmological test.","feed_headline":"Spectrotomography detects cluster shear at 3-sigma in A1767 and A2065","feed_subtitle":"Clean spectroscopic separation yields signals consistent with dynamical masses and scaling with redshift.","key_machinery":"Spectrotomography, weak lensing tomography that relies exclusively on spectroscopically confirmed background galaxies to separate them from cluster members.","core_discovery":"Spectrotomography using only galaxies with spectroscopic redshifts yields detections of tomographic shear signals at 3.1 sigma for A1767 and 3.5 sigma for A2065. The shear amplitudes are consistent with the clusters' dynamical caustic masses and scale appropriately with source redshift. This spectroscopic approach cleanly separates cluster members from the background and reduces potential systematics from photometric redshifts.","pith_inferences":["Subtle potential systematics noted in the A2029 comparison could affect applications to larger Subaru, Euclid, and LSST samples.","The technique opens a path to a geometric cosmological test independent of other probes once more clusters are measured.","Extension to additional clusters would provide a larger sample of unbiased weak lensing masses."],"forward_implications":["Shear signal amplitudes match the cluster dynamical caustic masses.","Signals scale appropriately with source redshift.","The spectroscopic method suppresses systematics that photometric redshifts can introduce.","The three detections including A2029 set the stage for broader unbiased cluster mass determinations and a potential geometric cosmological test."],"fun_headline_variants":["Spectrotomography detects 3.1-sigma shear for A1767","3.5-sigma shear detected for A2065 using spectra","Signals match caustic masses and scale with redshift","Spectroscopic method reduces photometric redshift systematics","Tomographic weak lensing at 3-sigma in A1767 and A2065"],"cache_read_input_tokens":64,"weakest_assumption_plain":"Spectroscopic redshifts cleanly separate background galaxies from cluster members with negligible contamination or selection effects, and shear measurements on the bright background galaxies are free from subtle systematics.","fun_headline_variants_meta":{"raw":{"variants":["Spectrotomography detects 3.1-sigma shear for A1767","3.5-sigma shear detected for A2065 using spectra","Signals match caustic masses and scale with redshift","Spectroscopic method reduces photometric redshift systematics","Tomographic weak lensing at 3-sigma in A1767 and A2065"]},"model":"grok-4.3","cost_usd":0.006885,"raw_usage":{"total_tokens":3215,"prompt_tokens":707,"num_sources_used":0,"completion_tokens":87,"cost_in_usd_ticks":68849500,"prompt_tokens_details":{"text_tokens":707,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":2421,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":707,"tokens_out":87,"duration_ms":13992,"temperature":1.0,"reasoning_tokens":2421,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-06-27T08:19:01.053061+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"A measurement in which the tomographic shear amplitudes fail to match the caustic dynamical masses or do not increase with source redshift would falsify the detection claim.","supporting_citations":[],"review_version":1}