{"id":"4d1308f1-7af0-46a3-8b79-fe0d1417c9a6","arxiv_id":"2603.03042","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":4.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"The paper text reports 16 newly confirmed dual quasars and 36 projected quasar pairs from SDSS/DESI spectra, but the arXiv metadata claims 17 and 143 — the two sets of counts do not match.","lead":"This paper reports new spectroscopically confirmed quasar pairs selected from Gaia astrometry; the text finds 16 dual quasars and 36 projected quasars, while the arXiv metadata claims 17 and 143. It matters because kiloparsec-scale dual quasars are precursors to binary supermassive black holes, and the projected pairs offer background sightlines for CGM absorption studies.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The dual-quasar census is internally inconsistent (16/36 vs 17/143) and includes a self-identified strong lens candidate (J0023+0417), so the headline count is not yet supported.","rationale":"Read in good faith, this is a catalog paper that uses public spectra to confirm quasar-pair candidates. The selection method is straightforward and the paper provides finding charts, spectra, and parameters for each system, which is useful. The central claim, however, is the number of newly confirmed dual quasars, and that number is undermined by internal inconsistencies rather than by external consensus disagreement. The manuscript itself flags J0023+0417 as a high-confidence strong lens in Section 5.3, yet includes it in the dual-quasar table and count. In addition, the front abstract reports 17 dual and 143 projected quasars while the body reports 16 and 36; this cannot be dismissed as a trivial typo because it changes the claimed scientific output. The reader's weakest_assumption identified redshift accuracy and lensing exclusion; I agree on the lensing part, but the more immediate problem is that at least one object is self-identified as a lens and the counts are irreconcilable. The proposed test is concrete and feasible with existing or obtainable imaging. This does not reject the paper's overall value; it makes acceptance conditional on reconciling the counts and either removing J0023+0417 from the dual sample or clearly marking it as a lens candidate while recomputing sample statistics.","tokens_in":16596,"tokens_out":4097,"duration_ms":43472,"concrete_test":"Re-run the classification with J0023+0417 removed from the dual sample and reconcile the front-abstract counts with the body counts. Then acquire or use existing deep imaging (e.g., HST or Subaru/AO) for all 16 'dual' systems, searching for a foreground deflector; in particular, measure the redshift of the red object between the J0023+0417 members. If that object is a lower-redshift galaxy and a lens model reproduces the 8.98-arcsec image separation, the dual count must drop to 15 (or fewer) and the paper should report the sample as '15 dual quasars plus one strong-lens candidate' or equivalent.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The central claim is the confirmation of 16 new dual quasars (text) or 17 (abstract). The count is load-bearing in two connected ways. First, the count is not internally consistent: the front abstract reports '17 dual quasars and 143 projected quasars', while the body (Section 2.2, Section 6, Table 1) reports 16 dual and 36 projected pairs. A reader cannot tell which census is being claimed. Second, the physical classification is contradicted by the paper itself: Section 5.3 states that J0023+0417's near-identical spectra, constant flux ratio, and a potential foreground galaxy 'strongly favor' a gravitational-lens interpretation, yet this system is included in Table 1 and counted among the 16 dual quasars; Section 4.1.1 only says lensing 'cannot be excluded'. The method for separating duals from lenses (Section 5.1) relies on the absence of an 'obvious deflector' in DESI-LS DR9 imaging, but Section 5.3 shows such a deflector candidate exists for J0023+0417. That imaging criterion is also weaker than needed to exclude group-scale or faint deflectors at 4-12 arcsec separations. Thus the central claim, that these 16 systems are physically distinct dual quasars, rests on an assumption that the manuscript itself demonstrates to be violated for at least one object.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper reports spectroscopic confirmation of quasar pair candidates selected from the MGQPC catalog, using DESI DR1 and SDSS DR16 spectra retrieved through SPARCL. The classification separates physical dual quasars from projected pairs using the literature velocity-difference criterion |Δvr| ≤ 2000 km/s, followed by visual inspection. The body of the manuscript reports 16 dual quasars and 36 projected pairs, with parameters in Tables 1 and 2. One system, J0023+0417, is separately argued in §5.3 to be a high-confidence strong lensing candidate, yet it is included in the dual-quasar count. A second, incompatible set of numbers appears in the arXiv abstract (17 dual quasars and 143 projected quasars), and the paper's series number also differs between the title and abstract. The projected-pair sample is presented as useful foreground-background sightlines for CGM absorption studies.","tokens_in":16923,"tokens_out":3822,"duration_ms":34599,"significance":"If the corrected sample is as claimed, the paper would add a modest but useful number of confirmed dual quasars and close projected quasar pairs to the existing census, with potential applications to merger-driven SMBH growth and CGM absorption studies. The work uses public spectroscopic data, applies a standard literature threshold, and includes visual spectral inspection and imaging checks. However, the central quantitative claim is currently inconsistent (16/36 vs 17/143), and one object counted as a dual quasar is internally identified as a likely gravitational lens. These issues must be resolved before the scientific content can be assessed reliably; the data products, once corrected, could still support a publishable catalog paper.","major_comments":[{"comment":"The central census is internally inconsistent. The arXiv abstract reports '17 dual quasars and 143 projected quasars,' while the title, §2.2, §3, §6, and Tables 1–2 report 16 dual quasars and 36 projected quasars. The reader cannot determine which sample is being claimed, and the two numbers cannot be reconciled from the text. This is the paper's main quantitative result, so the correct counts must be stated consistently in the abstract, body, and tables.","section":"Abstract and §2.2/§3/§6"},{"comment":"J0023+0417 is counted as a dual quasar in Table 1 and in the total of 16, but §4.1.1 states that a lensed interpretation 'cannot be excluded,' and §5.3 says that the nearly identical spectra, constant flux ratio, and a potential foreground galaxy 'strongly favor' a gravitational-lens interpretation. These statements contradict the classification. The system should either be removed from the dual-quasar sample and presented separately as a lens candidate, or the paper must justify why it remains in the dual census despite the evidence in §5.3.","section":"§4.1.1, §5.3, Table 1"},{"comment":"The lensing-exclusion criterion used to separate duals from lenses is the absence of an 'obvious deflector' in DESI-LS DR9 imaging. For separations of 4–12 arcsec, group-scale or faint deflectors may not be obvious in survey imaging, and J0023+0417 demonstrates that a potential foreground galaxy was indeed present in at least one system classified as a dual. The criterion needs quantitative support, e.g., limiting surface brightness/magnitude within the relevant radius, and it should be applied to all systems, not only selected ones.","section":"§5.1 and §5.3"},{"comment":"The description of MGQPC version 2 says 'we first remove the 58 confirmed dual quasars reported in this work,' but this paper reports 16 dual quasars (or 52 total pairs). The number 58 is inconsistent with the rest of the paper and makes the construction of the updated catalog, including the final count of 3643 candidates, non-transparent. Please clarify the arithmetic and the relationship to the 52 newly confirmed pairs.","section":"§5.4"}],"minor_comments":[{"comment":"The text says that 37 of 52 systems exceed the 2000 km/s threshold (leaving 15 duals), then a redshift calibration error changed one classification, yielding 16 duals and 36 projected. The intermediate arithmetic should be spelled out so the final numbers are auditable.","section":"§2.2"},{"comment":"Redshift uncertainties are not propagated into the |Δvr| values. All tabulated |Δvr| for the duals are below 2000 km/s by a wide margin, so this is unlikely to change the classification, but reporting uncertainties would strengthen the velocity-difference criterion.","section":"Table 1"},{"comment":"The series number is inconsistent: the arXiv metadata and one abstract say 'IV' and 'fourth in the series,' while the paper title and body say 'III' and 'third in the series.' This should be harmonized.","section":"Title / running head"},{"comment":"The text alternates between 'projected quasars' and 'projected quasar pairs' (e.g., §3 title says 'projected quasars' but §6 says 'projected pairs'). Define the terminology once and use it consistently.","section":"§3 and §6"},{"comment":"There are several typos, e.g., 'both both' and 'deflactors' in §4.1.4, 'Disscussion' in the §5 title, and a malformed first reference with a missing author name. A careful proofreading pass is needed.","section":"Throughout"}],"recommendation":"major_revision","confidential_remarks":"The discrepancy between the abstract (17/143) and the body (16/36) is severe enough that the editor may wish to check which version of the manuscript was submitted. The body's numbers are internally coherent except for the J0023+0417 classification and the §5.4 '58' inconsistency. If the authors correct the counts, remove or reclassify J0023+0417, and add quantitative support for the lensing-exclusion criterion, the paper could be suitable for publication. The current version is not."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"You should know this paper before the authors do: the sample itself is fine and useful, but the central numbers do not add up. The abstract reports 17 dual quasars and 143 projected quasars. The text, Section 2.2, Section 6, and the tables report 16 dual quasars and 36 projected quasars. Section 5.4 then says the authors remove “58 confirmed dual quasars reported in this work,” which is not 16 or 17. You cannot tell from the paper which census is being claimed, and that is a load-bearing problem because the title and abstract advertise specific counts.\n\nWhat is genuinely new: 16 confirmed dual quasars and 36 projected pairs drawn from the MGQPC catalog and confirmed with public DESI DR1 and SDSS DR16 spectra. The method is not new—it was established earlier in the series—but the paper does solid housekeeping: it removes overlaps with Jing et al. 2025a, cross-matches against SLED, and visually inspects every spectrum. The five projected pairs with rp below 30 kpc are a legitimate resource for future CGM absorption work. The authors are also transparent about the lensing ambiguity, which is more than many catalog papers do.\n\nBut the soft spots are real. J0023+0417 is described in Section 5.3 as a high-confidence strong lens candidate: near-identical spectra, constant flux ratio, a visible potential foreground galaxy. Yet it sits in Table 1 and is counted among the 16 dual quasars. That is not a minor inconsistency; it directly undermines the physical classification of the sample. The authors rely on the absence of an “obvious deflector” in DESI-LS imaging to separate duals from lenses, and then their own best case demonstrates that criterion is insufficient. They also do not propagate redshift uncertainties into the |Δvr| values in Table 1, which matters for borderline classifications. These are all fixable, but they are not cosmetic.\n\nThe work is reproducible in the important sense: public spectra, clear selection criteria, a standard velocity threshold from Hennawi et al. 2010, and the full tables are presented. The reader’s stress-test concern holds up. This should go to peer review, but the referee should insist that the authors reconcile the counts, move J0023+0417 out of the dual sample or clearly flag it as a lens candidate, and add velocity uncertainties. After that, this will be a modest but citable addition to the dual-quasar census.","headline":"A useful but sloppy catalog paper: the headline counts don't match the text, and the one 'interesting' system is likely a lens, not a dual quasar.","tokens_in":17415,"tokens_out":1873,"would_cite":false,"duration_ms":20483,"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":"This paper reports the spectroscopic confirmation of 16 dual quasars and 36 projected quasar pairs selected by Gaia astrometry, using the 2000 km/s line-of-sight velocity difference to separate physical pairs from chance alignments, and fla","keywords":["dual quasars","quasar pairs","Gaia astrometry","proper motion and parallax selection","spectroscopic confirmation","gravitational lensing","circumgalactic medium","supermassive black hole mergers"],"falsifier":"Re-observing the 16 claimed dual quasars with high-resolution spectroscopy and imaging that reaches below the current survey depth would settle the classification: a confirmed foreground galaxy with matching spectra in any system would move it to the lens column, and redshift measurements with precision well below 200 km/s would test whether the |Δvr| values are real. Counting the systems in the published tables would immediately resolve the abstract-vs-body discrepancy in the sample size.","tokens_in":16475,"feed_emoji":"🔭","tokens_out":7328,"duration_ms":70105,"temperature":0.7,"pith_summary":"The paper tries to turn a large catalog of quasar-pair candidates built from Gaia astrometry into a spectroscopically confirmed sample. It retrieves archival spectra from DESI and SDSS, applies a standard velocity-difference cut of 2000 km/s, visually inspects every spectrum, and ends up with 16 dual quasars at redshifts 0.609–2.758 plus 36 projected pairs where the two quasars are unrelated line-of-sight coincidences. That matters because kiloparsec-scale dual quasars are thought to be the immediate precursors of binary supermassive black holes and eventually low-frequency gravitational-wave sources, while close projected pairs give foreground-background sightlines through the circumgalactic medium. Along the way the paper finds one system, J0023+0417, whose nearly identical spectra and a possible foreground galaxy make it a likely gravitational lens rather than a true pair.","feed_headline":"Gaia motion filter confirms 16 new dual quasars","feed_subtitle":"DESI and SDSS spectra also sort 36 chance-aligned quasar pairs for gas studies.","key_machinery":"The load-bearing selection is the MGQPC catalog of 4,112 candidate pairs built from Gaia astrometry: quasars are expected to have essentially zero proper motion and parallax, so an optically selected companion to a known quasar that also shows null astrometric signal is a candidate physical companion. The confirmation machinery is archival spectroscopy: DESI DR1 and SDSS DR16 spectra, followed by a line-of-sight velocity difference computed from the two catalog redshifts with the standard formula, a 2000 km/s cut, and visual inspection of every spectrum. The velocity cut does the dual/projected separation; the imaging and spectral comparisons do the lens rejection; the J0023+0417 example sho","core_discovery":"The central claim is that an astrometric selection — quasars have near-zero proper motion and parallax in Gaia, so candidates near known quasars with the same null signal are likely companions — can be converted into a reliable spectroscopically confirmed sample using archival data. Cross-matching the candidate catalog against DESI DR1 and SDSS DR16, removing known lenses and duplicates, and applying |Δvr| ≤ 2000 km/s, the paper identifies 16 new dual quasars (z = 0.609–2.758) and 36 new projected quasar pairs. Visual inspection of every spectrum is part of the method; it caught one redshift calibration error that would otherwise have misclassified a pair. The paper also presents one likely","pith_inferences":["Inference: The opening abstract states 17 dual and 143 projected quasars, while the body and summary report 16 and 36; this count mismatch needs to be resolved before the sample is used for statistical inference.","Inference: If the zero-proper-motion filter is as efficient as this sample suggests, applying it to deeper or future Gaia data releases should reveal more close quasar pairs than fiber-fed surveys select, because it does not rely on color or double-peaked line morphology.","Inference: The 2000 km/s cut is a rough separator; some pairs labeled projected could be physically associated quasars with large infall velocities, so the reported dual-quasar count is likely a lower limit on the true physical-pair fraction.","Inference: The J0023+0417 example implies that a few percent of astrometrically selected pair candidates will turn out to be lenses; deeper near-infrared imaging of the other 15 dual systems would test whether any more hide a foreground deflector."],"forward_implications":["The 16 confirmed dual quasars, eight at z ≥ 1.5, add to the small spectroscopically confirmed census of kiloparsec-scale pairs at cosmic noon, where galaxy mergers and black-hole accretion peak.","The five projected pairs with projected separations below 30 kpc provide foreground-background sightlines that can be used in future absorption-line studies of the circumgalactic medium around the foreground quasar host.","Several projected pairs have Lyα forest coverage in the background spectrum, which could be used to search for a transverse proximity effect near the foreground quasar.","J0023+0417, if follow-up mass modeling confirms the lens interpretation, becomes a wide-separation (≈9″) lensed quasar with interesting microlensing diagnostics from the chromatic flux ratio.","The cleaned candidate catalog, with 3,643 remaining candidates, gives future follow-up programs a target list with known confirmed systems removed."],"fun_headline_variants":["Gaia zero-motion filter reveals 17 dual quasars","17 dual quasars, 143 projected pairs confirmed via astrometry","Quasar pairs from null motion: 17 dual, 143 projected","Spectroscopic follow-up yields 17 dual quasars, 143 projected","Astrometric selection plus DESI/SDSS nets 17 dual quasars"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The whole dual-versus-projected classification rests on the catalog redshifts being accurate enough that the 2000 km/s line-of-sight velocity cut separates true physical pairs from chance alignments, and on survey imaging being deep enough that any foreground lensing galaxy would be visible; the J0023+0417 system already violates the second assumption in one case.","fun_headline_variants_meta":{"raw":{"variants":["Gaia zero-motion filter reveals 17 dual quasars","17 dual quasars, 143 projected pairs confirmed via astrometry","Quasar pairs from null motion: 17 dual, 143 projected","Spectroscopic follow-up yields 17 dual quasars, 143 projected","Astrometric selection plus DESI/SDSS nets 17 dual quasars"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000657,"raw_usage":{"total_tokens":2864,"prompt_tokens":785,"completion_tokens":2079,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":529,"completion_tokens_details":{"reasoning_tokens":1984}},"tokens_in":529,"tokens_out":2079,"duration_ms":17837,"temperature":1.0,"reasoning_tokens":1984,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-02T19:10:13.044582+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Re-observing the 16 claimed dual quasars with high-resolution spectroscopy and imaging that reaches below the current survey depth would settle the classification: a confirmed foreground galaxy with matching spectra in any system would move it to the lens column, and redshift measurements with precision well below 200 km/s would test whether the |Δvr| values are real. Counting the systems in the published tables would immediately resolve the abstract-vs-body discrepancy in the sample size.","supporting_citations":[],"review_version":1}