{"id":"d97c1e90-9dcb-4627-935b-3bbece7562c1","arxiv_id":"2509.03027","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":8,"one_line_summary":"SMGs around z~2-3 quasars outside virial radii resemble field SMGs, while combined literature data show lower gas fractions inside quasar halos, suggesting environmental effects act only on halo scales.","lead":"This paper reports ALMA and NOEMA detections of carbon monoxide lines from 15 massive dusty galaxies around nine quasars at redshift 2-3, confirming that they sit outside the quasars' dark-matter halos. It compares their gas, dust, and star-formation properties with field galaxies and concludes that dense environments only affect such galaxies once they fall inside a quasar's halo.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The halo-scale depletion claim rests on a heterogeneous fgas comparison: outside sources include double-Gaussian profiles while inside literature sources are single-Gaussian only, and the key median differences are below ~2σ.","rationale":"The reader's weakest assumption (fixed re, alpha_CO, fDM, and halo mass) is real but would shift all fgas values in the same direction and does not by itself break the relative inside/outside trend. More damaging is the asymmetry in how the two sides of Figure 9 are constructed: the manuscript's own statistics show that most of its outside SMGs are double-Gaussian, while the inside literature points are restricted to single-Gaussian fits. Because Eq. (2) uses FWHM as a dynamical mass proxy, a merger or interacting-pair width is not equivalent to a disk rotation width; including these sources in the outside bin can produce a spuriously high fgas. The absence of a significance test is also critical: the quoted medians overlap at <2σ, so the abstract's phrase 'significantly impact' is not supported by the evidence as presented. I would keep the reader's CONDITIONAL verdict, but the conditions should explicitly include a homogeneous line-profile selection and a two-sample significance test. Independent strengths—completeness simulations, deblending checks, consistency checks against field CO luminosity functions for supplementary sources, and clear caveats about sensitivity—support the paper's value, but they do not yet secure the headline environmental conclusion. I also note the filament width inconsistency between §4.2 (4.0±2.6 and 3.5±2.2 cMpc) and §5 (4.9±2.3 and 5.8±3.1 cMpc); this is a reporting error, not the main issue.","tokens_in":33433,"tokens_out":10902,"duration_ms":106106,"concrete_test":"Recompute Figure 9 using only single-Gaussian sources in both the AMUSE^2 primary sample and the literature samples, recalculate fgas from Eq. (2), and run a bootstrap permutation test comparing the inside and outside medians. If the outside median drops to within 1σ of the field median, or if the inside/outside difference is not significant at p<0.05, the halo-scale-only environmental conclusion is not supported.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper's central conclusion—that environment only affects SMGs within quasar virial radii—depends on the fgas gradient in Figures 8–9. Three linked problems make that gradient insecure. First, Eq. (2) assumes a single rotation-dominated dynamical equilibrium, but §3.1 finds that 73% of the primary sample are better fit by double Gaussians, described as 'rotating disks or interacting pairs.' For interacting pairs, FWHM is not a virial estimator, and using it in Eq. (2) can overestimate fgas. The footnote attached to the literature list in §4.1.2 restricts the 'inside halo' literature points to single-Gaussian fits, while the blue Mpc-scale AMUSE^2 sample appears to include all primary sources; this asymmetry can inflate the outside median (92±40) relative to the inside median (26±13) without any environmental effect. Second, even taken at face value, the key contrasts are not statistically significant: inside vs field (26±13 vs 50±25) and outside vs field (92±40 vs 50±25) overlap at <2σ, and no two-sample significance test is reported. Third, the inside/outside split assumes Mhalo=10^12.5 Msun and treats projected distance as 3D separation; a different halo mass or deprojection would move sources across the boundary. The paper is careful about sensitivity limits, but the headline claim is stronger than the current evidence supports.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This manuscript presents ALMA and NOEMA CO(4-3)/CO(3-2) follow-up of 101 SCUBA-2 850 micron sources in nine z~2-3 quasar fields hosting Ly-a nebulae, confirming 15 physically associated SMGs. The authors derive CO line kinematics, far-infrared SEDs, gas fractions, depletion timescales, and gas-to-dust ratios, and compare these with field SMGs and literature DSFGs around quasars. They report that SMGs outside quasar virial radii resemble field SMGs, while DSFGs inside the virial radius show depleted gas fractions, and that the SMGs trace tentative filamentary structures with scale widths of a few cMpc. Cumulative star-formation rates and SFR densities are compared with simulations and other protocluster observations and are explicitly flagged as lower limits.","tokens_in":33708,"tokens_out":5920,"duration_ms":54391,"significance":"If the main deduction holds, the paper provides one of the first environmental-gradient measurements for massive dusty galaxies at cosmic noon, with a separation scale set by the quasar halo virial radius. The strengths include the careful ALMA/NOEMA reduction, the Monte Carlo completeness and false-detection analyses, the AICc-based line-profile selection, and the explicit caveats about lower limits and the tentative filament detection. The main limitation is that the headline gas-fraction gradient rests on a heterogeneous comparison and on median differences whose statistical significance is not demonstrated; the conclusion is therefore plausible but not yet established at the strength claimed in the abstract and Section 4.1.6.","major_comments":[{"comment":"The gas-fraction comparison in Figure 9 is not apples-to-apples. The inside-halo literature points are restricted to single-Gaussian fits, as stated in footnote 2, while the outside-halo sample plotted in blue includes all primary sources, 73% of which are better described by double Gaussians (§3.1.1). Equation (2) assumes a single rotation-dominated disk in dynamical equilibrium; for the double-Gaussian sources the FWHM entered in Eq. (2) is a composite width defined in §3.1.1, not the width of a single dynamically relaxed component, so the outside fgas values are not on the same footing as the inside values. I ask the authors to recompute fgas for the full sample with a uniform single-Gaussian extraction, or to restrict both sides to kinematically simple sources, and to show that the inside/outside gradient survives that restriction.","section":"§4.1.2, Eq. (2), footnote 2"},{"comment":"The central claim of gas depletion inside the virial radius is not supported by a reported statistical test. The medians are fgas = 26±13 inside, 92±40 outside, and 50±25 for field SMGs; the inside/outside contrast is only about 1.6σ and the outside/field contrast about 0.9σ, yet no two-sample test is given. Because the conclusion is built on these medians, the authors should report bootstrap or rank-sum p-values for each pairwise comparison and for a trend of fgas with projected distance, and state how many individual sources drive the gradient.","section":"§4.1.2, Figure 9"},{"comment":"The inside/outside classification depends on the assumed halo mass and on treating projected separation as a 3D distance. For Mhalo = 10^12.5 Msun at z~3 the virial radius is ~100-200 kpc, but changing Mhalo by a factor of a few moves Rvir by a comparable factor, and sources near the boundary can switch bins under a mild deprojection. The authors should test the sensitivity of the median fgas gradient to Mhalo in the range 10^12-10^13 Msun and to a simple statistical deprojection, and report how many sources change classification.","section":"§4.1.2, Figures 9-10"},{"comment":"The outside-halo sample comes from a survey that preferentially detects high-L'CO sources, and the text acknowledges that fainter CO sources outside the virial radius may be missed. This selection effect could bias the outside median fgas upward relative to the deeper literature samples used for the inside and field comparisons. The comparison should be strengthened by applying the same L'CO/FWHM sensitivity cut to all three samples, or by computing upper limits for the non-detected sources and recomputing the gradient with those limits.","section":"§4.1.2, Figure 8"}],"minor_comments":[{"comment":"The conclusion quotes filament widths of 4.9±2.3 cMpc (x-y) and 5.8±3.1 cMpc (x-z), whereas Section 4.2 reports λ = 4.0±2.6 cMpc (x-y) and λ = 3.5±2.2 cMpc (x-z); please reconcile the two sets of numbers.","section":"§5, conclusion item 5"},{"comment":"The text contains a typo: 'with a mdeian fgas of 26 ± 13' should read 'with a median fgas of 26 ± 13'.","section":"§4.1.2"},{"comment":"The reference entry for Wang et al. (2024) reads 'arVix, 240616637W' and appears malformed; please correct it to the full arXiv identifier and journal information.","section":"References"},{"comment":"The curve-of-growth correction is applied as a single factor of 2.0 to all sources based on the median/mean convergence; please state explicitly how the scatter among individual curves is propagated into the line luminosities and the derived fgas values.","section":"§3.1.2 and Figure 3"}],"recommendation":"major_revision","confidential_remarks":"The paper is honest and the observational material is valuable, but the headline claim needs the methodological and statistical work described in the major comments. If the authors cannot demonstrate significance on a homogeneous sample, the conclusion should be softened to a tentative trend rather than stated as a result. The filament detection is already appropriately labeled tentative, which is to the authors' credit."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Thanks for the note on AMUSE^2. Quick take: this is a genuinely useful observational paper — 15 new CO-confirmed SMGs around nine Ly-alpha nebulae, with careful completeness simulations, AICc line fitting, and honest lower limits. The outside-vs-field comparisons (CO line widths, Tdust, depletion times, gas-to-dust) look solid and are consistent with prior work. The supplementary-source CO luminosity function check is a nice touch, and the paper clearly labels the filament detection as tentative.\n\nThe soft spot is exactly where the stress-test note points. The inside-halo gas depletion claim in Figure 9 rests on fgas from Equation (2), which assumes rotation-dominated disks with fixed re, alpha_CO, fDM, and a guessed halo mass. The medians overlap: inside vs field 26±13 vs 50±25, outside vs field 92±40 vs 50±25 — both <2σ, and no two-sample test is reported. More worrying, the comparison is asymmetric: the footnote in Section 4.1.2 restricts literature points to single-Gaussian fits, but the blue Mpc-scale points include the authors' own double-Gaussian sources. Since double-Gaussian FWHM overestimates the dynamical mass, that asymmetry inflates the outside median. That is a real flaw, not a quibble.\n\nThere is also an internal inconsistency: filament widths in Section 4.2 are λ=4.0±2.6 and 3.5±2.2 cMpc, but Section 5 quotes 4.9±2.3 and 5.8±3.1 cMpc. Same analysis, different numbers. Probably a typo, but it needs fixing.\n\nThe other results — 73% double-Gaussian fraction, 350 km/s peak separation, Tdust/β values — agree with field SMGs, which is the more secure conclusion. The paper's own caveat about detection limits (brightest 17%, half the sources possibly below sensitivity) is appropriately flagged.\n\nBottom line: deserves a serious referee, but the abstract oversells the environmental conclusion. With a two-sample significance test, symmetric treatment of line profiles, and consistent numbers, this would be a solid MNRAS/ApJ contribution. As is, I'd ask for major revision on the fgas comparison. Worth reading for the data.","headline":"Solid new CO data for 15 SMGs around quasars, but the headline claim that environment matters only inside the virial radius is carried by a pile of assumptions and sub-2sigma medians.","tokens_in":34341,"tokens_out":2592,"would_cite":true,"duration_ms":25130,"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":"Dense quasar halos deplete gas in dusty galaxies only inside the halo, at roughly 100–200 kpc scales at cosmic noon.","keywords":["submillimeter galaxies","dusty star-forming galaxies","quasar environments","molecular gas fraction","CO line emission","Lyα nebulae","protoclusters","cosmic noon"],"falsifier":"A direct test is deeper CO spectroscopy of dusty galaxies at projected distances just outside the virial radius, reaching the CO luminosities typical of the inside-halo sources: if those faint outer galaxies show gas fractions as low as the depleted inner ones, the boundary at the virial radius disappears. Alternatively, stellar-mass-based gas fractions or kinematic inclination measurements for a few galaxies near the boundary would reveal whether the fixed disk assumptions create the trend artificially.","tokens_in":33186,"feed_emoji":"🔭","tokens_out":5157,"duration_ms":48858,"temperature":0.7,"pith_summary":"The paper sets out to show that the dense environment around a quasar at cosmic noon (z≈2–3) alters the gas content of massive dusty star-forming galaxies only once they enter the quasar's halo, on scales of roughly 100–200 kpc. It confirms 15 submillimeter galaxies around nine quasars with Lyα nebulae, measures their CO line emission and far-infrared brightness, and finds that outside the virial radius these galaxies look just like field submillimeter galaxies: similar line widths, dust temperatures, depletion times, and gas-to-dust ratios. Inside the virial radius, however, combined literature data show median gas fractions of 26±13%, close to the quasars themselves (20±10%), while field-like values are 50±25% or higher. If correct, this locates the onset of environmental influence on massive galaxies at halo scales rather than megaparsec scales, which would help reconcile earlier contradictory results.","feed_headline":"Only quasar halos drain gas from dusty galaxies at cosmic noon","feed_subtitle":"SMGs outside the virial radius keep field-like gas; inside it they drop to quasar levels.","key_machinery":"The load-bearing element is the gas-fraction estimator of Chen et al. (2021), Equation (2), which converts a measured CO line width and CO line luminosity into a gas fraction by assuming a rotation-dominated disk in dynamical equilibrium with a fixed half-light radius re=3 kpc, a CO-to-H2 conversion factor αCO=1.0, and a dark-matter fraction fDM=0.12. This estimator lets the authors compare gas fractions across samples that lack direct stellar masses. The virial radius split, which sets the boundary between 'inside halo' and 'outside halo,' assumes quasar halos of mass ~$10^{12}$.5 Msun and treats projected distances as physical separations. The comparison also relies on published field SMG samples to anchor the expected field values.","core_discovery":"The central claim is that the molecular gas fraction of dusty star-forming galaxies depends on their distance from a quasar: galaxies inside the quasar's virial radius have depleted gas fractions comparable to the quasar hosts, while galaxies outside the virial radius are indistinguishable from field submillimeter galaxies. The evidence is a set of ALMA and NOEMA CO detections around nine quasars at z≈2–3, combined with published measurements of dusty galaxies and quasars at similar redshifts. The paper also reports that 73% of its confirmed CO emitters are better fit by double-Gaussian line profiles with a median peak separation of 350±25 km/s, consistent with rotating disks or interacting pairs, and that the spatial distribution of confirmed members traces a filament-like structure with a scale height of 2–5 comoving Mpc, though this structural detection is statistically tentative. Its cumulative star-formation rates are lower limits and agree with simulation predictions once the comparison volumes are matched.","pith_inferences":["If the radial gas-fraction trend is real, it implies that gas loss begins at first infall through the virial radius, before cluster-core processes act; the natural mechanisms are ram-pressure stripping or strangulation by the hot halo, though the paper does not establish which one operates.","A testable extension is to measure gas fractions for individual dusty galaxies with inclination corrections and stellar-mass-based estimates on both sides of the virial radius; the median split seen in the paper should sharpen rather than wash out if the claim is correct.","The double-Gaussian line fraction matching field SMGs suggests that the internal kinematics of these galaxies are largely set before they enter the halo, since the environment does not yet dominate their dynamics at these separations.","A prediction implicit in this picture is that the brightest dusty galaxies inside the virial radius should show either an elevated star-formation efficiency or a suppressed star-formation rate relative to their gas mass; existing infrared and CO measurements could test this directly."],"forward_implications":["If the central claim is correct, the dense quasar environment stops modifying the interstellar medium of massive dusty galaxies at roughly the halo boundary (~100–200 kpc), while galaxies beyond that distance remain essentially field-like.","Previously contradictory results would be reconciled: studies that measured galaxies at megaparsec separations would naturally see little environmental effect, while studies probing the core would see depleted gas fractions.","Dusty galaxies inside the virial radius are consistent with being gravitationally bound to the quasar halo, while those outside are consistent with the Hubble flow, so the measured gas fractions can be mapped onto infall through the halo periphery.","The filament-like arrangement of confirmed members, with similar widths in the sky and line-of-sight directions (λ ≈ 4.0 and 3.5 cMpc), supports a cylindrical or elongated pancake shape for the large-scale structure traced by these galaxies.","The measured star-formation rate densities are lower limits, and once comparison volumes are matched to simulations they agree with model predictions, so future deeper surveys are needed before claiming a tension between observations and simulations."],"supporting_citations":[{"why":"Supplies the gas-fraction estimator of Equation (2) and the reference case of a dusty galaxy with depleted gas around the Slug ELAN.","marker":"Chen et al. (2021)"},{"why":"Provides the main field SMG comparison sample for line widths, CO luminosities, and the r31/r41 conversion ratios.","marker":"Birkin et al. (2021)"},{"why":"The SCUBA-2 850 µm survey from which the targets are drawn, including the overdensity measurements and filament rotation angles used in the spatial analysis.","marker":"Arrigoni Battaia et al. (2023)"},{"why":"Provides a field SMG comparison sample for dust temperature, infrared luminosity, and gas-fraction baselines.","marker":"Dudzevičiūtė et al. (2020)"},{"why":"Supplies the bright field SMG sample used for comparing CO properties, dust properties, and gas fractions.","marker":"Liao et al. (2024)"},{"why":"Provides the spectroscopically confirmed SMG sample around HS1549+19 used to cross-check the filament width measurement.","marker":"Wang et al. (2024)"},{"why":"Gives the standard conversion from CO line intensity to CO luminosity used throughout the analysis.","marker":"Carilli & Walter (2013)"},{"why":"The cosmological simulation whose volumes and cumulative star-formation predictions are used for the SFR density comparisons.","marker":"Yajima et al. (2022)"}],"fun_headline_variants":["Quasar halos strip gas from dusty galaxies; outside they're normal","Gas depletion in dusty galaxies occurs only inside quasar halos","Dense quasar environs dry out massive dusty galaxies","Field-like gas persists in dusty galaxies beyond quasar halos","Cosmic noon: quasar halos drain gas, outskirts keep it"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The result depends on converting measured CO line widths and luminosities into gas fractions with a fixed set of assumptions—rotation-dominated disks, half-light radius of 3 kpc, CO conversion factor of 1.0, and a dark-matter fraction of 0.12—and on treating the quasars as $10^{12}$.5 Msun halos with projected distances equal to true separations. If those assumptions fail, the gas-depletion trend inside virial radii is not established.","fun_headline_variants_meta":{"raw":{"variants":["Quasar halos strip gas from dusty galaxies; outside they're normal","Gas depletion in dusty galaxies occurs only inside quasar halos","Dense quasar environs dry out massive dusty galaxies","Field-like gas persists in dusty galaxies beyond quasar halos","Cosmic noon: quasar halos drain gas, outskirts keep it"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000607,"raw_usage":{"total_tokens":2891,"prompt_tokens":1073,"completion_tokens":1818,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":689,"completion_tokens_details":{"reasoning_tokens":1728}},"tokens_in":689,"tokens_out":1818,"duration_ms":13769,"temperature":1.0,"reasoning_tokens":1728,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-15T16:34:22.953399+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A direct test is deeper CO spectroscopy of dusty galaxies at projected distances just outside the virial radius, reaching the CO luminosities typical of the inside-halo sources: if those faint outer galaxies show gas fractions as low as the depleted inner ones, the boundary at the virial radius disappears. Alternatively, stellar-mass-based gas fractions or kinematic inclination measurements for a few galaxies near the boundary would reveal whether the fixed disk assumptions create the trend artificially.","supporting_citations":[{"cited_title":"2024, ApJ, 494, 25","cited_arxiv_id":null,"evidence_quote":"Supplies the bright field SMG sample used for comparing CO properties, dust properties, and gas fractions."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides the spectroscopically confirmed SMG sample around HS1549+19 used to cross-check the filament width measurement."},{"cited_title":"2022, MNRAS, 509, 4037","cited_arxiv_id":null,"evidence_quote":"The cosmological simulation whose volumes and cumulative star-formation predictions are used for the SFR density comparisons."}],"review_version":1}