{"id":"72054fe9-8eb9-44e4-ab4f-f78618a2ade4","arxiv_id":"2508.21229","paper_version":2,"verdict":"ACCEPT","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"Spectroscopic follow-up of the completed HSC-SSP survey yields 43 new quasars, 11 candidate obscured quasars, and 29 galaxies at z 5.71 to 7.02.","lead":"This paper reports 54 new quasars and candidate obscured quasars, plus 29 galaxies, from the completed Subaru HSC survey of the reionization era between redshift 5.7 and 7.0. It is likely the final major discovery installment of the SHELLQs project, adding low-luminosity active galactic nuclei that help bridge JWST-detected AGNs and classical quasars.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Reported 43/11/29 breakdown is not reproducible from Table 1: several 'quasars' satisfy the paper's own narrow-line candidate criterion (FWHM<500 km/s, LLyα>10^43), so the quasar count is visually set.","rationale":"The reader identified the quasar/galaxy visual classification as the weakest assumption. I agree that this is the softest point, but I found a more specific and more damaging version: several objects in Table 1 satisfy the paper's own quantitative definition of candidate obscured quasars yet are classified as quasars. Since the abstract's central claim is the numerical breakdown (43+11+29), this is directly load-bearing. The paper is otherwise careful, internally consistent in its caveats, and the two candidate obscured objects with JWST confirmation are real supporting evidence. The issue is not fraud or even a fatal flaw; it is that the classification rule is not applied transparently enough for the headline counts to be verified from the published material. A homogeneous spectral re-fitting test would decide whether the counts change materially. If they do, the abstract and Table 1 need correction; if they do not, the authors should state why the visual 'broad bump' differs from the tabulated FWHM. Therefore I would move from ACCEPT to CONDITIONAL: accept the catalog once this reproducibility check is passed or the classification criteria are quantified.","tokens_in":20701,"tokens_out":9861,"duration_ms":101412,"concrete_test":"Re-measure the 72 EoR spectra with a uniform Lyα profile fit: model each line as a narrow Gaussian (FWHM<500 km/s) plus a broad Gaussian (FWHM>1000 km/s) plus a Lyman-break continuum. Classify as quasar only if the broad component is significantly detected (e.g., ΔBIC>10) and contributes >10% of the line flux; as candidate obscured if the line is narrow with LLyα>10^43; otherwise galaxy. Report how many of J135818, J115900, J023811, J223942, and the published 11 candidate obscured quasars switch class. If more than three objects move, the headline 43/11/29 counts need revision; if none move, the visual 'hint' is not captured by the quoted FWHM and should be explicitly quantified.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The central claimed counts (43 quasars, 11 candidate obscured quasars, 29 galaxies) depend on the Section 3 rule: objects with 'a hint of broad spectral bump around Lyα' are quasars, while luminous narrow Lyα emitters (LLyα>10^43 erg/s, FWHM<500 km/s) are candidate obscured quasars. Applying that numerical criterion to Table 1 gives concrete contradictions: J135818.89−013249.7 (FWHM=430±130, log L=44.07), J115900.87+025819.2 (FWHM=430±30, log L=44.17), J023811.54+040416.5 (FWHM=300±300, log L=43.57), and J223942.28+040943.2 (FWHM=480±140, log L=43.24) are listed as quasars even though each meets the stated candidate-obscured threshold. Either the FWHM/luminosity measurements are unreliable for these objects, or the visual 'hint of a broad bump' overrode the quantitative boundary. Thus the abstract's 43/11/29 split is not reproducible from the published table. This does not threaten the existence of a substantial high-redshift AGN population, but it does make the exact headline counts load-bearing and currently unsupported by the paper's own stated criteria.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This is the 24th SHELLQs paper and reports spectroscopic results for 132 photometric quasar candidates observed with Subaru/FOCAS and GTC/OSIRIS between 2021 November and 2025 March. The main result is the identification of 43 broad-line quasars at 5.71 ≤ z ≤ 7.02, 11 candidate obscured (narrow-line) quasars at 6.01 ≤ z ≤ 6.88, and 29 galaxies at z ≈ 5.56–6.28, including a z = 7.02 quasar and two luminous galaxies at z = 5.98 separated by 900 kpc that may trace an overdensity. The paper also identifies 5 [O III] emitters at z < 1, 30 Galactic brown dwarfs, and 14 passive galaxies at z ≈ 1.5–2.2 as contaminants, and it presents full spectra, line measurements, and an observation journal in Tables 1 and 2. Statistical analysis of the full SHELLQs sample is deferred to a future paper.","tokens_in":21075,"tokens_out":8206,"duration_ms":78125,"significance":"If the classifications are correct, this is a valuable final discovery sample from a major survey: it extends the low-luminosity quasar sample into the epoch of reionization with a z = 7.02 quasar and a possible z = 5.98 overdensity, and it adds 11 candidate obscured quasars, two of which have already been independently confirmed as mildly obscured quasars by JWST/NIRSpec. The paper is careful in flagging sky-noise features, reporting measurement uncertainties, labeling the obscured class as 'candidate,' and testing the brown-dwarf versus passive-galaxy separation with a template-fitting check. These strengths make the catalog useful for future JWST follow-up and for the planned full-sample statistical analysis. However, the exact 43/11/29 breakdown is not reproducible from Table 1 using the paper's own stated criteria, and this issue is load-bearing for the headline counts.","major_comments":[{"comment":"Section 3 defines candidate obscured quasars as objects with LLyα > 10^43 erg/s and FWHM < 500 km/s, but Table 1 lists four objects in the Quasars section that satisfy these criteria: J135818.89−013249.7 (FWHM 430±130, log LLyα 44.07), J115900.87+025819.2 (430±30, 44.17), J023811.54+040416.5 (300±300, 43.57), and J223942.28+040943.2 (480±140, 43.24). The later sentence that quasars are identified by 'a hint of broad spectral bump around Lyα' could in principle resolve the inconsistency, but the paper does not state that these four objects show such a bump, nor does it explain how the FWHM/luminosity criterion is applied when a broad bump is present. The abstract and title counts (43 and 11) therefore cannot be checked from the published table. Please reclassify the objects or provide an explicit decision rule, including the treatment of FWHM errors and upper limits, that makes the table","section":"§3, Table 1"},{"comment":"The paper states that 'we classified objects with a hint of broad spectral bump around Lyα as quasars, and the remaining objects as galaxies,' and acknowledges that the separation 'is not always straightforward.' This is a subjective visual criterion with no quantitative significance threshold, yet the 43/29 split between quasars and galaxies is a headline result and will feed the forthcoming statistical analysis. Since Table 1 does not record the presence or significance of a broad component, a reader cannot reproduce the classification from the published data. Please provide a quantitative measure (e.g., the significance of a broad-line component, a Δχ² criterion, or a line-asymmetry index), or at minimum a per-object classification-quality flag distinguishing secure and marginal quasars.","section":"§3, quasar/galaxy separation paragraph"}],"minor_comments":[{"comment":"The abstract states the EoR objects span 5.71 ≤ z ≤ 7.02, but the galaxy list in Table 1 includes J145945.34+415206.4 at z = 5.56. Please clarify how 'similar redshifts' is defined or adjust the stated range.","section":"Abstract / Table 1"},{"comment":"J220754.87+065111.8 appears as two rows (Lyα and N V) without a merged label. Please make clear that the second row is an additional line of the same object.","section":"Table 1"},{"comment":"There is a typo: 'althouth' should be 'although'.","section":"§3, brown dwarf / passive galaxy discussion"},{"comment":"Several FWHM entries are upper limits (e.g., '< 230') and many have large uncertainties. The caption should state explicitly whether FWHM values are central values from a single Gaussian fit and how upper limits are derived.","section":"Table 1 caption"},{"comment":"The text uses 'S21A and S23B internal data releases' and later 'S23B DR'; define DR at first use for readers outside the HSC project.","section":"§2"}],"recommendation":"major_revision","confidential_remarks":"I agree with the reader that this is a useful and honest observational catalog and that the existence of a substantial high-redshift AGN population is not in doubt. My main reservation is the reproducibility of the exact 43/11/29 counts, which are the headline result; the four table rows flagged in my major comment make the counts unsupported by the paper's own quantitative criterion. This is fixable by reclassification or by an explicit decision rule, so I recommend major_revision rather than rejection. I would not require new observations."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"This is exactly what it claims to be: the final major discovery installment of SHELLQs, reporting 43 quasars, 11 candidate obscured quasars, and 29 galaxies at 5.7 < z < 7.0. The spectra are shown with sky-noise caveats, the catalog table is usable, and the authors are honest about the fuzzy boundaries between quasars, galaxies, brown dwarfs, and passive galaxies. For someone working on high-redshift quasar demographics, this is a necessary reference catalog, and the completion of the full HSC-SSP candidate follow-up gives it archival value.\n\nThe one thing to watch is a genuine internal inconsistency, exactly as the stress-test note says. Table 1 lists several objects as quasars that meet the paper's own stated threshold for candidate obscured quasars (LLyα > 1e43 erg/s and FWHM < 500 km/s): J115900.87+025819.2 (FWHM 430±30, log L 44.17), J135818.89−013249.7 (FWHM 430±130, log L 44.07), J023811.54+040416.5 (FWHM 300±300, log L 43.57), and J223942.28+040943.2 (FWHM 480±140, log L 43.24). The paper says objects with luminous narrow Lyα are classified as candidate obscured quasars, but these four are classified as quasars. Either the visual 'hint of a broad bump' overrides the quantitative rule, or the FWHM measurements are unreliable for these objects, or the rule is only a rough guideline. The authors need to state which one it is and ideally re-present the affected objects. This does not threaten the existence of a substantial high-redshift AGN population, but it does mean the exact counts in the abstract are not reproducible from the published table.\n\nThe z=5.98 galaxy pair is an interesting suggestion of an overdensity, but the authors themselves note that additional spectroscopy is required, so I would not overweight it. The brown-dwarf/passive-galaxy split is also acknowledged as uncertain by the authors, and the reduced-χ2 test they report is a reasonable sanity check.\n\nBottom line: this deserves a serious referee. It is a solid, honest survey paper with a fixable classification inconsistency. A referee should ask the authors to clarify the decision rule, reclassify or justify those four objects, and adjust the abstract counts if needed. After that, publish.","headline":"A useful final SHELLQs discovery catalog whose headline 43/11 split is not fully reproducible from Table 1 because four objects listed as quasars satisfy the paper's own narrow-line candidate criterion.","tokens_in":21636,"tokens_out":3640,"would_cite":true,"duration_ms":36655,"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 final SHELLQs spectroscopic batch adds 43 quasars, 11 obscured-quasar candidates, and 29 galaxies from the epoch of reionization.","keywords":["high-redshift quasars","epoch of reionization","SHELLQs survey","Lyman-alpha emitters","obscured quasars","quasar luminosity function","Hyper Suprime-Cam","active galactic nuclei"],"falsifier":"Observe the 29 newly classified galaxies with JWST/NIRSpec in the rest-optical: if a substantial fraction show broad Hα or He I lines, they are actually obscured quasars and the 43/29 split is wrong. Separately, a deep narrow-band or spectroscopic map around the two z = 5.98 galaxies would show whether there is a real overdensity or just a random pair.","tokens_in":20669,"feed_emoji":"🔭","tokens_out":8147,"duration_ms":78529,"temperature":0.7,"pith_summary":"This is the final major discovery installment of a decade-long project that hunts for the faintest quasars in the era when the first stars and black holes were reionizing the universe. It reports spectra of 132 photometric candidates drawn from the completed Subaru/Hyper Suprime-Cam survey: 43 turn out to be quasars at redshifts 5.71–7.02, 11 are candidate obscured quasars (luminous narrow Lyα emitters), and 29 are galaxies at similar redshifts. The batch includes a quasar at z = 7.02, several very faint active galactic nuclei that bridge JWST-discovered objects and bright quasars, and two z = 5.98 galaxies separated by 900 kpc that may trace a galaxy overdensity. The paper is deliberately a catalog paper: it establishes these objects as real, while the statistical analysis of the full sample is deferred to the next publication.","feed_headline":"43 new reionization-epoch quasars close out SHELLQs survey","feed_subtitle":"Spectroscopy of 132 candidates also yields 11 obscured-quasar candidates and a possible galaxy overdensity at z = 6.","key_machinery":"The working objects are dropout-selected quasar candidates from HSC imaging, chosen by i/z/y color cuts or a Bayesian probability algorithm and requiring a spectral break; the decisive observable is the Lyα region, where broad emission and blue continuum mark quasars, narrow bright Lyα marks candidate obscured quasars, and weak or absent Lyα marks galaxies. A relaxed image-shape criterion (µ/µ_PSF < 3.0 in the z band for i-dropouts) was added to recover more extended sources. Redshifts and line properties come from R ~ 1200–1500 optical spectroscopy with FOCAS and OSIRIS.","core_discovery":"The authors claim to have spectroscopically identified the last major batch of low-luminosity quasars from the completed HSC-SSP imaging survey: 43 broad-line quasars at 5.71 ≤ z ≤ 7.02, 11 candidate obscured (narrow-line) quasars at 6.01 ≤ z ≤ 6.88, and 29 galaxies at similar redshifts, bringing the project's census of broad-line epoch-of-reionization quasars to 182. Quasars are recognized by a broad Lyα bump and blue continuum with the sharp intergalactic-medium break; objects with luminous (L > 10^43 erg/s) narrow Lyα emission are classed as candidate obscured quasars, a reading supported by JWST/NIRSpec, which found broad Balmer lines in seven of eleven previously known members. Two gala","pith_inferences":["The visual quasar/galaxy split is the softest point: if better data moved even a handful of objects across the boundary, the 43/29 numbers would shift, though the existence of a substantial high-redshift population would stand.","If the z = 5.98 pair is a genuine overdensity, the same dropout technique could be used to find protoclusters in the HSC footprint by searching for pairs of luminous galaxies at coincident redshifts, not only isolated quasars.","The narrow-line, L > 10^43 erg/s population may be the ground-based counterpart of JWST's broad-Balmer and 'little red dot' AGNs; cross-matching the two samples could measure the obscured fraction of AGNs during reionization.","Adding near-IR photometry would cleanly separate the 30 brown-dwarf contaminants from the 14 z ≈ 2 passive galaxies, improving the purity of future high-z quasar selections."],"forward_implications":["If the identifications are correct, the SHELLQs census now contains 182 broad-line quasars at 5.6 < z < 7.1, a sample large enough to anchor the faint end of the quasar luminosity function at the end of reionization.","The z = 7.02 and z = 6.72 quasars, with M1450 ≈ −25.6 and −25.7, become high-priority targets for ALMA and JWST studies of early black-hole–host connections.","The two z = 5.98 galaxies separated by 900 kpc give a concrete target for verifying whether a galaxy overdensity or protocluster exists in that field.","The JWST-confirmed broad Balmer lines in previously reported narrow-line sources support using L_Lyα > 10^43 erg/s as a practical AGN selection criterion at z > 6.","Because the shape cut was relaxed, the paper demonstrates that extended i-dropouts can also host epoch-of-reionization quasars, implying earlier size-based cuts were discarding some real sources."],"supporting_citations":[{"why":"Defines the SHELLQs project and its Lyα-based classification of quasars versus galaxies, which this paper follows.","marker":"Matsuoka et al. 2016"},{"why":"Supplies the Bayesian probabilistic algorithm used to pick photometric quasar candidates from HSC colors.","marker":"Mortlock et al. 2012"},{"why":"Sets the previous candidate-selection criteria and the redshift uncertainty scale that the present paper adopts and extends.","marker":"Matsuoka et al. 2022"},{"why":"Basis for interpreting luminous narrow Lyα emitters (L > 10^43 erg/s) as AGN-dominated, hence candidate obscured quasars.","marker":"Konno et al. 2016"},{"why":"JWST/NIRSpec follow-up shows broad Balmer lines in seven of eleven previously reported narrow-line objects, validating the obscured-quasar classification.","marker":"Matsuoka et al. 2025"},{"why":"Established the z ≈ 7 quasar luminosity function that this sample will extend with the faintest objects.","marker":"Matsuoka et al. 2023"},{"why":"Independently discovered one quasar (J142817.13+045430.3) also reported here, corroborating that identification.","marker":"Belladitta et al. 2025"}],"fun_headline_variants":["Final SHELLQs batch: 43 reionization-epoch quasars","SHELLQs ends with 43 new high-z quasars and 11 obscured candidates","Last SHELLQs haul: 43 quasars at z>5.7 and 11 obscured candidates","Subaru survey's final quasar discovery: 43 at reionization epoch","54 new quasars and candidates close out SHELLQs survey"],"cache_read_input_tokens":2688,"weakest_assumption_plain":"The classification of each object as a quasar or a galaxy rests on a visual judgment of whether a broad spectral bump is present around Lyα—a judgment the authors admit is not always straightforward; if wrong for some objects, the stated counts would change, even though the population as a whole would survive.","fun_headline_variants_meta":{"raw":{"variants":["Final SHELLQs batch: 43 reionization-epoch quasars","SHELLQs ends with 43 new high-z quasars and 11 obscured candidates","Last SHELLQs haul: 43 quasars at z>5.7 and 11 obscured candidates","Subaru survey's final quasar discovery: 43 at reionization epoch","54 new quasars and candidates close out SHELLQs survey"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001387,"raw_usage":{"total_tokens":5490,"prompt_tokens":819,"completion_tokens":4671,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":563,"completion_tokens_details":{"reasoning_tokens":4563}},"tokens_in":563,"tokens_out":4671,"duration_ms":33678,"temperature":1.0,"reasoning_tokens":4563,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-05T14:27:37.287339+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Observe the 29 newly classified galaxies with JWST/NIRSpec in the rest-optical: if a substantial fraction show broad Hα or He I lines, they are actually obscured quasars and the 43/29 split is wrong. Separately, a deep narrow-band or spectroscopic map around the two z = 5.98 galaxies would show whether there is a real overdensity or just a random pair.","supporting_citations":[{"cited_title":"doi:10.48550/arXiv.2505.04825","cited_arxiv_id":null,"evidence_quote":"JWST/NIRSpec follow-up shows broad Balmer lines in seven of eleven previously reported narrow-line objects, validating the obscured-quasar classification."}],"review_version":1}