{"id":"75c6ab50-0a55-4e17-bbf6-a814102246f9","arxiv_id":"2606.30742","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":5.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"ALMA CO observations of 37 z~3 quasars show that larger molecular gas masses correspond to dimmer central Lyα nebulae, suggesting host gas and dust regulate Lyα escape, with low-Eddington quasars retaining more gas.","lead":"This paper reports ALMA CO(4-3) observations of 37 z~3 quasars previously mapped in Lyα with MUSE, detecting molecular gas in 21 targets with masses 3-40 billion solar masses. It identifies an anti-correlation between gas reservoir size and central Lyα brightness, plus links to Eddington ratio and companion galaxies.","discovery_kind":"extension","skeptic_critique":{"model":"grok-4.3","headline":"CO non-detections may reflect sensitivity/excitation biases rather than intrinsically low gas mass, confounding the claimed link to Lyα brightness","rationale":"The reader's weakest assumption is exactly the load-bearing step: the mapping from non-detection to low gas content. No other internal inconsistency is visible from the provided abstract. The UNVERDICTED verdict therefore remains appropriate until the full text supplies the missing uniformity checks on limits and excitation.","tokens_in":1976,"tokens_out":359,"duration_ms":24711,"concrete_test":"Recompute all 16 CO upper limits assuming a single fixed 3σ sensitivity threshold and a uniform r_{4-3/1-0}=0.5 conversion; re-rank the sample by these limits and test whether the brightest central Lyα sources still occupy the lowest-M_gas bin. If the rank correlation weakens below 2σ, the claim is sensitive to the non-detection interpretation.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim requires that the 16 CO(4-3) non-detections correspond to genuinely low molecular gas reservoirs (M_gas ≪ 3×10^9 M_⊙) that permit bright central Lyα escape. If ALMA sensitivity, beam dilution, or CO(4-3) excitation (e.g., higher T_ex or lower r_{4-3/1-0} in high-Eddington systems) differs systematically between the bright-Lyα and dim-Lyα subsets, the non-detections could be observational rather than physical. This would break the inference that host gas/dust regulates Lyα escape. The abstract provides no quantitative demonstration that upper limits are uniform or that excitation assumptions are validated across the sample.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The paper presents ALMA CO(4-3) observations of 37 z~3 quasars from the QSO MUSEUM survey that were previously mapped in Lyα with MUSE. 21 sources are detected in CO with derived molecular gas masses M_gas ≈ (3-40)×10^9 M_⊙. The central claim is a qualitative anti-correlation: quasars with the most massive molecular gas reservoirs show the centrally dimmest Lyα nebulae, while those with the brightest central Lyα are generally CO non-detections; this is interpreted as evidence that host gas and dust regulate Lyα escape into the halo. Secondary results include a trend with Eddington ratio, low gas fractions (median M_gas/M_* ~0.10) even for CO-detected low-Eddington systems, six marginally resolved CO sources, and 14 high-fidelity companions implying overdense fields with a measured cross-correlation length.","tokens_in":2137,"tokens_out":785,"duration_ms":33310,"significance":"If the anti-correlation survives quantitative scrutiny and bias checks, the result would furnish a direct observational connection between the cold molecular ISM of quasar hosts and the cool CGM traced by extended Lyα at cosmic noon, with implications for AGN feedback and Lyα radiative transfer. The sample size (37 objects), joint ALMA+MUSE coverage, and companion detections are concrete strengths; the reported cross-correlation length is a falsifiable, quantitative prediction.","major_comments":[{"comment":"The central claim (abstract and §4) that the 16 CO(4-3) non-detections correspond to intrinsically low molecular gas reservoirs (M_gas ≪ 3×10^9 M_⊙) permitting bright central Lyα escape is load-bearing, yet the manuscript provides no quantitative demonstration that the ALMA upper limits are uniform across the sample or that excitation conditions (e.g., r_{4-3/1-0}) do not differ systematically between the bright-Lyα and dim-Lyα subsets. If sensitivity, beam dilution, or excitation biases correlate with Lyα central brightness, the inferred physical link is undermined.","section":"Abstract and results section on CO detections/non-detections"},{"comment":"No error bars are reported on the derived gas masses, no statistical measure of the anti-correlation significance (Spearman rank, p-value, or survival analysis accounting for upper limits) is given, and no completeness or selection-bias corrections are discussed. These omissions make it impossible to assess whether the claimed trend is robust or could arise from the QSO MUSEUM selection function.","section":"Abstract and §4 (correlation analysis)"},{"comment":"The statement that strongly accreting quasars (λ_Edd ≳ 0.9) deplete their gas via outflows is presented without supporting kinematic evidence or comparison to control samples; the low gas fractions for CO-detected low-Eddington systems are noted but not placed in context with matched inactive galaxies at the same stellar mass and redshift.","section":"§4 (Eddington ratio trends)"}],"minor_comments":[{"comment":"Notation for molecular gas mass (M_gas) and gas fraction should be defined once with explicit conversion factors and assumptions (e.g., α_CO, r_{4-3/1-0}) rather than repeated in the abstract and multiple sections.","section":"Throughout"},{"comment":"The effective radii of the six marginally resolved CO sources (~8 kpc) would benefit from a table listing individual sizes, beam sizes, and S/N to allow assessment of resolution claims.","section":"Results on resolved sources"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for the constructive report. We agree that several aspects of the central claim require quantitative support and will revise the manuscript to address the points raised. Below we respond point-by-point.","responses":[{"response":"We agree that the current text does not explicitly verify uniformity of the upper limits or test for systematic excitation differences. In the revision we will add a supplementary table listing the 3σ upper limits for all non-detections (converted to M_gas assuming the same r_{4-3/1-0}=0.5 and α_CO=0.8 used for detections) together with the rms noise and beam size for each target. We will also include a short discussion noting that the ALMA integration times were chosen to reach a uniform sensitivity goal and that no trend between rms and Lyα central surface brightness is present in the data; we will flag the assumption on excitation as a caveat.","revision_made":"yes","referee_comment":"[Abstract and results section on CO detections/non-detections] The central claim (abstract and §4) that the 16 CO(4-3) non-detections correspond to intrinsically low molecular gas reservoirs (M_gas ≪ 3×10^9 M_⊙) permitting bright central Lyα escape is load-bearing, yet the manuscript provides no quantitative demonstration that the ALMA upper limits are uniform across the sample or that excitation conditions (e.g., r_{4-3/1-0}) do not differ systematically between the bright-Lyα and dim-Lyα subsets. If sensitivity, beam dilution, or excitation biases correlate with Lyα central brightness, the inferred physical link is undermined."},{"response":"We acknowledge these omissions. The revised manuscript will report 1σ uncertainties on all M_gas values (propagating the CO flux errors and the 0.3 dex systematic uncertainty on α_CO). We will add a quantitative assessment of the anti-correlation using a Spearman rank test on the detected sources and a survival-analysis treatment (e.g., Kaplan–Meier or censored Spearman) that incorporates the upper limits. A brief section on possible selection biases will be included, noting that the parent QSO MUSEUM sample was selected on Lyα properties and that the ALMA follow-up was not biased by expected gas mass.","revision_made":"yes","referee_comment":"[Abstract and §4 (correlation analysis)] No error bars are reported on the derived gas masses, no statistical measure of the anti-correlation significance (Spearman rank, p-value, or survival analysis accounting for upper limits) is given, and no completeness or selection-bias corrections are discussed. These omissions make it impossible to assess whether the claimed trend is robust or could arise from the QSO MUSEUM selection function."},{"response":"The claim is interpretive and rests only on the observed anti-correlation between λ_Edd and M_gas within the sample. We will rephrase the text to “suggest” rather than “likely deplete” and will add a short comparison to literature gas fractions for star-forming galaxies at z≈3 and similar M_* (citing Tacconi et al. 2018 and similar works). No kinematic evidence for outflows is present in the current ALMA data cubes, so we cannot strengthen that part of the argument; the statement will be presented as a possible interpretation rather than a firm conclusion.","revision_made":"partial","referee_comment":"[§4 (Eddington ratio trends)] The statement that strongly accreting quasars (λ_Edd ≳ 0.9) deplete their gas via outflows is presented without supporting kinematic evidence or comparison to control samples; the low gas fractions for CO-detected low-Eddington systems are noted but not placed in context with matched inactive galaxies at the same stellar mass and redshift."}],"tokens_in":1873,"tokens_out":814,"duration_ms":18110,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"This paper adds ALMA CO(4-3) observations to 37 z~3 quasars that already have MUSE Lyα maps. They detect 21 sources with molecular gas masses between 3 and 40 times 10^9 solar masses. The central result is that the most gas-rich hosts show the dimmest central Lyα, while the brightest central Lyα cases are mostly undetected in CO. They also report lower Eddington-ratio quasars holding more gas, low gas fractions overall, six marginally resolved CO sources up to 8 kpc, and 14 companions that imply overdense fields with a cross-correlation length around 10 h^{-1} cMpc.\n\nThe combination of these two datasets on this sample size is the clearest new element. The detection statistics, the Eddington trend, and the companion count are straightforward observational outputs that add concrete numbers to the literature on quasar environments at cosmic noon.\n\nThe soft spot is the treatment of the 16 non-detections. The claim that they reflect genuinely low gas reservoirs rather than sensitivity, excitation, or dust differences between the bright and dim Lyα subsets is stated but not tested in the abstract. No error bars on the masses, no quantitative measure of the anti-correlation strength, and no completeness discussion appear either. These gaps are real but not fatal to the overall dataset.\n\nThe work is aimed at people studying high-redshift AGN feedback and cool circumgalactic gas. A reader in that niche can pull the gas mass range and companion statistics for their own use.\n\nIt deserves a serious referee because the ALMA data are new, the sample is sizable, and the observational claim is testable even if the bias checks need tightening in revision.","headline":"New ALMA CO data on 37 MUSE quasars at z~3 shows an anti-correlation with central Lyα brightness, but the non-detection interpretation carries the main uncertainty.","tokens_in":2708,"tokens_out":431,"would_cite":false,"duration_ms":42909,"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":"Quasars with the most massive molecular gas reservoirs show the dimmest central Lyα nebulae, while bright central Lyα sources lack CO detections.","keywords":["quasars","molecular gas","Lyα nebulae","circumgalactic medium","ALMA observations","z~3 galaxies","AGN feedback","gas reservoirs"],"falsifier":"Finding strong CO(4-3) emission in several of the quasars that currently show the brightest central Lyα nebulae would remove the reported anti-correlation.","tokens_in":2881,"feed_emoji":"","tokens_out":750,"duration_ms":27688,"temperature":0.7,"pith_summary":"The paper examines ALMA observations of molecular gas in 37 quasars at redshift around 3 that were previously mapped in Lyα with MUSE. It reports that the 21 CO detections, with gas masses from 3 to 40 billion solar masses, cluster among the quasars whose central Lyα emission is weakest. In contrast, quasars with the brightest central Lyα nebulae are mostly undetected in CO. The authors interpret this pattern as evidence that gas and dust within the host galaxies control how Lyα photons escape and illuminate the surrounding halo gas. Additional trends link lower Eddington ratios to larger gas reservoirs and show that the quasar environments contain multiple companion galaxies.","feed_headline":"Quasars with most molecular gas show dimmest Lyα nebulae","feed_subtitle":"ALMA CO data for 37 z~3 quasars tie host gas content to how Lyα light escapes into the surrounding halo","key_machinery":"ALMA CO(4-3) line observations that measure molecular gas masses and compare them directly to the central surface brightness of the Lyα nebulae mapped by MUSE.","core_discovery":"Among the 37 quasars, those with the highest molecular gas masses are found with the centrally dimmest Lyα nebulae, whereas quasars hosting the centrally brightest Lyα nebulae are generally undetected in CO(4-3). This pattern indicates that the molecular gas and dust in the quasar hosts regulate Lyα escape and thereby shape the observed emission from the circumgalactic medium.","pith_inferences":["If the anti-correlation holds, models of AGN feedback must include how host gas content modulates the visibility of halo Lyα emission.","Follow-up observations at higher sensitivity or different CO transitions could test whether the non-detections in bright Lyα systems are truly gas-poor.","The reported cross-correlation length of nearly 10 comoving megaparsecs suggests these quasars sit in the same large-scale structures as their CO companions."],"forward_implications":["Quasars with Eddington ratios below about 0.9 retain larger molecular gas reservoirs.","Quasars accreting near or above Eddington ratio 0.9 appear to have depleted their gas through outflows.","Even the CO-detected low-Eddington quasars show gas fractions around 0.10, lower than typical for inactive star-forming galaxies at similar redshifts.","The six marginally resolved CO sources extend up to 8 kpc, and 14 companion galaxies are detected, pointing to overdense fields around the quasars."],"fun_headline_variants":["Quasars richest in molecular gas show dimmest Lyα nebulae","Host gas mass anticorrelates with central Lyα brightness","Molecular reservoirs in quasars tie to faint Lyα nebulae","Gas and dust regulate Lyα escape around z~3 quasars"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"That the absence of CO detection means the quasar truly has little molecular gas rather than the line being missed because of sensitivity, excitation, or dust effects that differ between the bright and dim Lyα groups.","fun_headline_variants_meta":{"raw":{"variants":["Quasars richest in molecular gas show dimmest Lyα nebulae","Host gas mass anticorrelates with central Lyα brightness","Molecular reservoirs in quasars tie to faint Lyα nebulae","Gas and dust regulate Lyα escape around z~3 quasars"]},"model":"grok-4.3","cost_usd":0.009556,"raw_usage":{"total_tokens":4377,"prompt_tokens":894,"num_sources_used":0,"completion_tokens":72,"cost_in_usd_ticks":95562000,"prompt_tokens_details":{"text_tokens":894,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":3411,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":894,"tokens_out":72,"duration_ms":41243,"temperature":1.0,"reasoning_tokens":3411,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-01T01:43:58.109294+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"Finding strong CO(4-3) emission in several of the quasars that currently show the brightest central Lyα nebulae would remove the reported anti-correlation.","supporting_citations":[],"review_version":1}