{"id":"eca61624-8fb4-4a45-b1b8-d3dbdd9a34c6","arxiv_id":"2606.25565","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":5.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":1,"one_line_summary":"Acoustic black holes produce larger Einstein ring radii, longer microlensing event durations, higher peak magnifications, and enhanced event rates compared to Schwarzschild black holes, with effects increasing with tuning parameter ξ.","lead":"The paper models galactic microlensing events using acoustic black holes with a tuning parameter ξ and finds larger Einstein rings, longer durations, and higher magnifications than standard Schwarzschild black holes. A smart generalist might read it to see how analogue gravity models could be tested with existing astronomical survey data.","discovery_kind":"unclear","skeptic_critique":{"model":"grok-4.3","headline":"Acoustic metrics govern sound waves in fluids, not photon null geodesics, so cannot be substituted into gravitational microlensing formulas","rationale":"The reader's weakest assumption correctly flags the substitution step but frames it as a parameter-matching issue rather than the more fundamental mismatch between acoustic effective metrics and spacetime geometry for light. The concern is internal to the argument (applicability of the metric) rather than external consensus. Because the full text is referenced but the abstract alone already exposes the substitution without justification, the claim does not survive scrutiny.","tokens_in":1769,"tokens_out":391,"duration_ms":13931,"concrete_test":"Derive the null geodesic equation and deflection angle α(b) for the acoustic metric at fixed mass M and impact parameter b; compare to the standard Schwarzschild result α(b) = 4GM/b. If the acoustic α(b) does not reduce to the GR expression when ξ → 0 or if the metric signature/fluid assumptions prevent consistent null geodesics for light, the microlensing predictions are invalid.","verdict_should_be":"REJECT","load_bearing_attack":"The central claim requires that the acoustic Schwarzschild metric (parameterized by ξ) functions as a spacetime metric whose null geodesics determine light deflection for microlensing observables (Einstein radius, event duration, peak magnification, event rate). Acoustic metrics are derived as effective metrics for acoustic perturbations in a background fluid flow (typically non-relativistic condensed-matter systems) and do not solve Einstein's equations or describe electromagnetic propagation. The paper uses observed stellar-mass BH parameters directly as lens mass/distance while inserting the acoustic line element into standard Paczyński light-curve expressions. This substitution is load-bearing: if the metric does not control photon paths, the reported ξ-dependent enhancements have no observational relevance. No independent derivation of the deflection angle from the acoustic metric's geodesic equation is indicated in the abstract or reader's summary.","agreement_with_reader":"partial"},"referee_report":{"model":"grok-4.3","summary":"The manuscript explores galactic microlensing by acoustic Schwarzschild black holes parameterized by a tuning parameter ξ, treating them as potential dark matter halo objects. Using observed parameters from black hole candidates (Cygnus X-1, A0620-00, GRO J1655-40) as lenses, it calculates that increasing ξ produces a larger Einstein ring radius, longer event duration, higher peak magnification in Paczyński light curves, and an enhanced microlensing event rate relative to standard Schwarzschild black holes, proposing microlensing surveys as a channel to constrain analogue gravity metrics.","tokens_in":1948,"tokens_out":423,"duration_ms":16961,"significance":"If the metric substitution were valid, the work would supply concrete, survey-accessible predictions that could test analogue models at galactic scales using existing microlensing data sets. The choice to anchor calculations to real observed BH parameters rather than purely theoretical ones is a strength, lending specificity to the claimed trends.","major_comments":[{"comment":"Abstract: the central claim that acoustic black holes produce ξ-dependent enhancements in Einstein radius, duration, peak magnification, and event rate rests on direct substitution of the acoustic line element into the standard Paczyński microlensing expressions, yet no derivation of the light-deflection angle from the null geodesic equation of the acoustic metric is supplied, nor is any argument given that this effective fluid metric governs photon propagation.","section":"Abstract"},{"comment":"Abstract: the reported directional trends with ξ are stated without equations, error budgets, data-exclusion criteria, or tests of robustness against changes in modeling assumptions (e.g., lens mass/distance priors or source distributions), so the soundness of the quantitative claims cannot be evaluated.","section":"Abstract"}],"minor_comments":[{"comment":"Abstract: the Paczyński light-curve reference contains a typesetting artifact (Paczy\\'{n}ski).","section":"Abstract"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for the constructive comments on our manuscript. We address each major comment point by point below, indicating revisions where appropriate.","responses":[{"response":"We agree that an explicit derivation of the deflection angle from the null geodesic equation in the acoustic metric, together with a justification for photon propagation under the effective fluid metric, would strengthen the presentation. The current manuscript proceeds by direct substitution into the standard Paczyński formalism, which is common in analogue-gravity literature but lacks the requested derivation. We will add a new subsection deriving the deflection angle and discussing the applicability of the acoustic metric to null geodesics.","revision_made":"yes","referee_comment":"[Abstract] Abstract: the central claim that acoustic black holes produce ξ-dependent enhancements in Einstein radius, duration, peak magnification, and event rate rests on direct substitution of the acoustic line element into the standard Paczyński microlensing expressions, yet no derivation of the light-deflection angle from the null geodesic equation of the acoustic metric is supplied, nor is any argument given that this effective fluid metric governs photon propagation."},{"response":"The directional trends with ξ are computed from the explicit expressions and numerical evaluations given in Sections 3 and 4, using the observed parameters of Cygnus X-1, A0620-00 and GRO J1655-40. We acknowledge, however, that the manuscript does not presently include error budgets, data-exclusion criteria or systematic robustness tests against variations in lens-mass/distance priors or source distributions. We will expand the results section to incorporate these elements.","revision_made":"yes","referee_comment":"[Abstract] Abstract: the reported directional trends with ξ are stated without equations, error budgets, data-exclusion criteria, or tests of robustness against changes in modeling assumptions (e.g., lens mass/distance priors or source distributions), so the soundness of the quantitative claims cannot be evaluated."}],"tokens_in":1380,"tokens_out":419,"duration_ms":18699,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The one thing to know is that this paper substitutes an acoustic metric into standard gravitational microlensing calculations, but acoustic metrics control sound propagation in fluids rather than light rays in spacetime. That step undercuts the claimed observational signatures.\n\nThe paper takes the acoustic Schwarzschild metric with tuning parameter ξ and applies it to microlensing by using masses and distances from real candidates like Cygnus X-1, A0620-00, and GRO J1655-40. It then computes changes to the Einstein ring radius, event duration, peak magnification in Paczyński light curves, and overall event rate. These trends all increase with ξ. The calculation appears new as a direct application to galactic microlensing surveys.\n\nWhat it does well is lay out the forward modeling clearly for a range of ξ values and tie it to existing survey data potential. The trends are presented as directional effects that could be searched for statistically.\n\nThe soft spot is the physical justification for the substitution itself. Acoustic black holes come from analogue gravity in condensed matter systems. Their effective metric is for perturbations in the fluid, not for the geometry that bends light according to general relativity. The paper acknowledges the difference from Einstein solutions but does not derive or cite a reason why the acoustic line element would produce the correct deflection angle for photons. Without that, the enhancements in the observables have no connection to real microlensing events.\n\nThe free parameter ξ is varied but not fitted to data, so there is no circularity in that sense. The math inside the model may be fine, but the model does not map onto the observations it claims to address.\n\nThis paper is mainly for specialists in analogue gravity who are exploring possible extensions to astrophysical settings. A general relativity or observational astrophysics reader will see the mismatch immediately. It does not rise to the level where a serious referee should spend time on it, because the central premise does not survive basic scrutiny of what the metric represents.\n\nI recommend against engaging with this work for citation or further development until the metric substitution is properly justified from first principles.","headline":"The acoustic metric substitution into microlensing formulas has no physical basis.","tokens_in":2484,"tokens_out":477,"would_cite":false,"duration_ms":23462,"reading_group":"no","serious_thinker":"no","would_accept_peer_review":false},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.3","headline":"Acoustic black holes produce larger Einstein rings, longer microlensing events, and higher peak magnifications than Schwarzschild black holes as the tuning parameter ξ grows.","keywords":["acoustic black holes","galactic microlensing","Schwarzschild metric","tuning parameter ξ","Einstein ring radius","Paczyński light curves","event duration","analogue gravity"],"falsifier":"A direct comparison of microlensing event statistics and light-curve parameters from current surveys against model predictions for different fixed values of ξ; if the data are consistent only with ξ equal to zero within measurement uncertainties, the claim of observable enhancement would be ruled out.","tokens_in":2666,"feed_emoji":"🕳️","tokens_out":685,"duration_ms":17558,"temperature":0.7,"pith_summary":"The paper calculates microlensing light curves for acoustic Schwarzschild black holes, which are characterized by a fluid-dynamical metric controlled by the tuning parameter ξ. It applies the metric to observed black hole candidates treated as galactic lenses and compares the results directly to the vacuum Schwarzschild case. Larger values of ξ increase the Einstein ring radius, extend event duration, raise peak magnification in the Paczyński curves, and raise the overall microlensing event rate. These changes imply that statistical patterns in microlensing survey data could distinguish acoustic metrics from standard vacuum solutions.","feed_headline":"Acoustic black holes yield larger Einstein rings and longer events","feed_subtitle":"The tuning parameter ξ enlarges the ring, extends duration, raises magnification, and boosts detection probability versus the vacuum case.","key_machinery":"The acoustic tuning parameter ξ that parametrizes deviations from the vacuum Schwarzschild metric and enters the deflection-angle calculation for microlensing observables.","core_discovery":"Using the acoustic Schwarzschild metric with tuning parameter ξ, the deflection angle and resulting Paczyński light curves show that larger ξ values increase the Einstein ring radius, prolong the microlensing event duration, and elevate the peak magnification compared to the ξ=0 Schwarzschild case. Consequently, the microlensing event rate and detection probability rise with ξ when applied to galactic black hole candidates.","pith_inferences":["Microlensing surveys could place limits on ξ by comparing aggregate statistics of events attributed to black hole candidates against the ξ=0 baseline.","If acoustic metrics are realized in nature, the same lensing modifications might appear in other analogue-gravity systems whose metrics admit a similar tuning parameter.","The approach supplies a concrete observational channel for testing whether dark-matter halo objects obey vacuum general relativity or fluid-based analogues at galactic distances."],"forward_implications":["The Einstein ring radius increases with rising ξ.","Microlensing event durations become longer as ξ grows.","Peak magnification in the light curves rises with ξ.","The microlensing event rate is higher for acoustic black holes than for their Schwarzschild counterparts.","The probability of detection grows as a function of ξ."],"fun_headline_variants":["Acoustic black holes enlarge Einstein rings via ξ tuning","ξ increases microlensing event duration for acoustic holes","Acoustic Schwarzschild raises magnification in galactic microlensing","Detection rates higher for acoustic black holes than Schwarzschild"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"Acoustic black holes with the same mass and distance parameters as observed candidates can be treated as gravitational lenses whose metric is fully specified by ξ and produces observable differences from the vacuum Schwarzschild metric at galactic scales.","fun_headline_variants_meta":{"raw":{"variants":["Acoustic black holes enlarge Einstein rings via ξ tuning","ξ increases microlensing event duration for acoustic holes","Acoustic Schwarzschild raises magnification in galactic microlensing","Detection rates higher for acoustic black holes than Schwarzschild"]},"model":"grok-4.3","cost_usd":0.003452,"raw_usage":{"total_tokens":1824,"prompt_tokens":671,"num_sources_used":0,"completion_tokens":60,"cost_in_usd_ticks":34524500,"prompt_tokens_details":{"text_tokens":671,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":1093,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":671,"tokens_out":60,"duration_ms":5966,"temperature":1.0,"reasoning_tokens":1093,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-06-25T20:36:21.001702+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"A direct comparison of microlensing event statistics and light-curve parameters from current surveys against model predictions for different fixed values of ξ; if the data are consistent only with ξ equal to zero within measurement uncertainties, the claim of observable enhancement would be ruled out.","supporting_citations":[],"review_version":1}