{"id":"1b68aa2d-c374-4364-8c67-02de26ddf6c4","arxiv_id":"2412.13065","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":7.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":5,"one_line_summary":"Cosmological zoom-in simulations show that suppressing the small-scale matter power spectrum, as expected in self-interacting dark matter models, reduces or erases the gravothermal core-collapse signature in dwarf-mass halos.","lead":"This paper simulates a Milky Way-like dark matter halo in eight models where the dark matter both self-interacts and has warm-dark-matter-like suppressed initial conditions. It finds that the power-spectrum suppression delays halo growth and removes many low-mass halos, sharply reducing the fraction of halos that undergo gravothermal core collapse, which changes predictions for dwarf galaxy density profiles.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Quantitative core-collapse fractions rest on an extrapolated parametric model; the paper's own T_kd=2.32 keV matched-halo check shows this extrapolation can fail, so Table 1's exact percentages are not directly simulated.","rationale":"The reader's primary weakest assumption is exactly the load-bearing concern: the parametric SIDM model is applied outside its validated regime to predict WSIDM core-collapse fractions, with the paper itself deferring detailed testing to future work. My reading strengthens this concern with internal evidence: Appendix C reports matched T_kd=2.32 keV subhalos whose actual WSIDM Vmax histories are enhanced relative to SIDM while the parametric tau0 distribution shifts lower, and the authors explicitly acknowledge that nonlinear effects not captured by the parametric model may affect gravothermal evolution. Because the quantitative abstract claim relies on these specific fractions, the exact percentages in Table 1 are less secure than the qualitative conclusion. However, the qualitative conclusion that P(k) suppression reduces core collapse is supported by direct simulation outputs: the Rmax-Vmax relations (Figures 4 and 5), the matched-subhalo evolution histories (Figure 7), and the density-profile results (Figures 8 and 15) all show a systematic shift away from deep core collapse as P(k) suppression strengthens. The paper also provides public data and code, which makes the proposed direct reclassification test feasible without new simulations. The single-host limitation is real but secondary, since the reported differences are larger than Poisson errors and the direction of the effect is physically expected from delayed growth and lower concentrations. Given that the reader already assigned CONDITIONAL, the correct adjustment is no change: the concern supports the conditional verdict rather than moving it to accept or reject. I would recommend the authors either run the direct classification test on existing snapshots or explicitly restate Table 1 as parametric-model predictions with an estimated systematic uncertainty from the untested WSIDM regime.","tokens_in":33045,"tokens_out":5415,"duration_ms":52409,"concrete_test":"Recompute the f_cc,iso,8 and f_cc,sub,8 columns of Table 1 using a direct simulation-based collapse criterion: for each SIDM/WSIDM (sub)halo above 10^8 Msun, classify as core-collapsed if its present-day Rmax-Vmax or central density deviates from the matched T_kd-only/CDM sibling by more than a threshold calibrated on known SIDM-collapsed objects, instead of using the parametric tau0 > 0.75 cut. Use the existing snapshots and focus on T_kd=2.32 keV subhalos, because Appendix C shows actual WSIDM Vmax histories enhanced while parametric tau0 shifts down. If any f_cc entry moves by more than 5 percentage points, the exact headline fractions are not robust and should be reported with a model-dependence caveat.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Every f_cc entry in Table 1 is produced by applying the Yang et al. (2024, 2025) parametric model to CDM or T_kd-only runs, not by classifying core collapse in the actual SIDM/WSIDM snapshots. The T_kd-only input histories omit the coupled tidal-stripping/gravothermal feedback that Section 5 itself identifies: tidal evolution changes subhalo density profiles, which changes stripping, which changes the Vmax histories that drive collapse. Appendix C provides a concrete internal warning: for matched T_kd=2.32 keV WSIDM subhalos, the actual WSIDM Vmax histories are slightly enhanced relative to SIDM while the parametric-model tau0 distribution shifts to lower values, and the authors state that 'it is possible that nonlinear effects that are not captured by the parametric model affect (sub)halos' gravothermal evolution.' Since the headline fractions (18% to 2%, 13% to 2%, etc.) come exactly from this extrapolation, a systematic error in tau0 near the collapse boundary (tau0 ~ 0.75) would change Table 1 without changing the qualitative direction of the result. The paper explicitly defers detailed testing of the parametric model in WSIDM to future work (Section 3.3), so the central quantitative claim currently rests on an assumption that the manuscript itself flags as unvalidated.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper presents eight new cosmological DM-only zoom-in simulations of a Milky Way-like host (Halo004) exploring the combined effects of a velocity-dependent SIDM cross section (MilkyWaySIDM) and suppressed linear matter power spectra motivated by a dark-photon-mediated WSIDM model. Three kinetic-decoupling temperatures (T_kd = 0.72, 1.46, 2.32 keV) are simulated both with and without self-interactions, along with CDM, SIDM, and WDM reference runs. The main result is that P(k) suppression reduces the fraction of core-collapsed (sub)halos relative to SIDM with CDM initial conditions, with the effect strongest for isolated halos and for the most suppressed P(k). The authors quantify this via the parametric gravothermal model of Yang et al. (2024, 2025) applied to CDM and T_kd-only simulations, and also show direct R_max-V_max relations and matched subhalo evolution histories from the WSIDM simulations. Additional results include (S)HMF suppression, subhalo density profile predictions matched to dwarf galaxies, and a central density-pericenter anticorrelation in some WSIDM models.","tokens_in":33377,"tokens_out":3932,"duration_ms":40041,"significance":"If the central qualitative claim holds, this is the first study to simulate gravothermal evolution, including core collapse, in SIDM models with WDM-like suppressed initial conditions. The paper identifies a physically important degeneracy: the same dark-sector physics that produces strong SIDM also suppresses dwarf-scale structure, partially erasing the core-collapse signature. This is directly relevant for interpreting upcoming dwarf galaxy, strong-lensing, and satellite-population data. The qualitative result is supported by direct simulation outputs, namely the R_max-V_max relations and matched V_max histories, which do not rely on the parametric model. The public release of halo catalogs, merger trees, and particle snapshots is a concrete strength. However, the headline quantitative fractions of core-collapsed halos in Table 1 and the abstract are not measured directly from the WSIDM snapshots; they are derived from a parametric model that the paper itself flags as untested in WSIDM.","major_comments":[{"comment":"The core-collapsed fractions in Table 1 and quoted in Sections 4.4 and 7.1 are not obtained by classifying core collapse in the actual SIDM/WSIDM simulation snapshots. Instead, they are computed by applying the parametric model of Yang et al. (2024, 2025) to the CDM and T_kd-only simulations. This is stated in Section 3.3, and Section 3.3 explicitly says 'We leave detailed testing of the parametric model in WSIDM for future work.' Given that the abstract and summary list exact percentages such as 18% dropping to 2% and 13% dropping to 2%, the headline quantitative claim rests on an extrapolation beyond the model's validated regime. The manuscript should either classify core collapse directly in the WSIDM runs (e.g., using the simulated density or V_max evolution) or clearly present Table 1 as parametric-model predictions with this caveat. The internal check in Appendix C for T_kd = 2.32 keV makes this concern concrete: the actual WSIDM subhalos show slightly enhanced V_max histories relative to SIDM, while the parametric-model tau_0 distribution shifts to lower values, and the authors state that nonlinear effects not captured by the parametric model may be at play.","section":"Section 3.3, Table 1, Section 4.4"},{"comment":"The core-collapsed fractions are quoted as single numbers without statistical uncertainties, despite being derived from a single zoom-in host. Table 1 reports 100 subhalos and 759 isolated halos above 10^8 M_sun in the CDM run; the SIDM and WSIDM runs have similar or smaller samples. Poisson errors on the quoted fractions are therefore non-negligible (e.g., for 18% of 100 subhalos the 1-sigma error is roughly 4 percentage points, and for 2% it is roughly 1.4 percentage points). Some differences between models, particularly between T_kd = 1.46 and 2.32 keV for subhalos (8% vs. 17%), may be statistically marginal. Additionally, the convergence test in Appendix A validates R_max and V_max distributions only for isolated halos with M_vir > 8 x 10^8 M_sun and does not quantify convergence for subhalos or for the 10^8 M_sun regime used for the core-collapsed fractions. The paper should provide uncertainties and either extend the convergence test to the relevant mass range or soften the precision of the reported fractions.","section":"Section 4.4, Table 1, Appendix A"},{"comment":"The matched-subhalo analysis in Section 5 and Appendix C reveals a qualitative tension for the T_kd = 2.32 keV model. The actual WSIDM V_max histories for the three matched subhalos are slightly enhanced relative to SIDM, yet the parametric model applied to the T_kd-only run predicts tau_0 distributions shifted to lower values. The paper acknowledges this in Appendix C, noting that nonlinear effects not captured by the parametric model may affect gravothermal evolution. This tension directly affects the reliability of the T_kd = 2.32 keV core-collapsed fraction in Table 1 (17% for subhalos). At minimum, the paper should quantify how much of the quoted fraction is robust to the parametric model's failure in this regime, or restrict the quantitative claim to models where the parametric model is validated against the direct WSIDM evolution.","section":"Section 5, Appendix C"}],"minor_comments":[{"comment":"The legend in the right panel of Figure 12 lists 'Tkd + SIDM' even though the panel compares T_kd-only and WDM subhalo mass functions; this appears to be a labeling error that should be corrected.","section":"Figure 12"},{"comment":"The statement that the authors present 'eight new high-resolution simulations' is correct, but it is easy to misread because Section 3.2 first lists eleven total simulations; consider adding an explicit enumeration of which are new.","section":"Section 3.2"},{"comment":"The definition of the core-collapsed threshold tau_0 > 0.75 is given with a reference to Roberts et al. (2024) in parentheses, but the text would benefit from a sentence explaining how sensitive the quoted fractions are to this threshold, since another threshold (e.g., 0.7 or 0.8) could change the absolute percentages.","section":"Section 3.3"},{"comment":"The sentence 'The core-collapsed fraction is expected to peak at roughly 10^8 M_sun' is presented without a direct citation or derivation; if this is from Ando et al. (2025), please make the citation explicit at that point.","section":"Section 4.4"},{"comment":"The convergence discussion in Appendix A.2 states that K-S tests yield p > 0.99 for V_max and p ~ 0.3 for R_max, but no p-values are shown for the subhalo distributions; if subhalo R_max-V_max convergence cannot be tested, this should be stated more prominently because the main core-collapse fractions include subhalos.","section":"Appendix A"}],"recommendation":"major_revision","confidential_remarks":"The paper is a solid contribution to an important and timely topic, and the direct simulation evidence for the qualitative suppression of core collapse is credible. The main reason for major revision, rather than rejection or acceptance, is that the headline quantitative fractions in Table 1 and the abstract are produced by applying a parametric model that the authors themselves identify as unvalidated in the WSIDM regime, and the internal T_kd = 2.32 keV check shows a concrete mismatch. I would encourage the editor to require that the authors either present direct classifications of core collapse from the WSIDM runs or clearly re-label Table 1 as parametric-model extrapolations with appropriate caveats and uncertainties. The single-host limitation is an additional concern for the exact percentages, though not for the qualitative trend."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"First, the headline: this paper finds something real. It is the first simulation suite in which P(k) suppression is mild enough to leave SIDM core collapse partially intact, and the direct simulation outputs show clearly that suppression weakens the collapse signature. The Rmax-Vmax relations and the matched subhalo histories are the strongest evidence; those do not depend on any parametric model. The paper is also refreshingly honest about its assumptions and ships data and code.\n\nWhat is new: the ETHOS simulations had such strong suppression that core collapse never occurred; here the T_kd = 2.32 keV model preserves a good fraction, and the trend across three cutoffs is sensible. The comparison to WDM-matched mass functions and the decomposition into “erasure of low-mass halos” versus “delayed growth” via reweighted SIDM tau0 distributions is clever and mostly convincing.\n\nSoft spots: the headline core-collapsed fractions in Table 1 are not measured from the SIDM or WSIDM snapshots. They come from the Yang et al. parametric model applied to CDM and T_kd-only runs. The paper says in Section 3.3 that testing the model in WSIDM is future work, and Appendix C contains a concrete warning: for T_kd = 2.32 keV, matched WSIDM subhalos have slightly enhanced Vmax histories relative to SIDM, while the parametric model shifts tau0 down. The authors even say nonlinear effects not captured by the model may affect gravothermal evolution. So the exact percentages should not be treated as direct simulation outputs. A systematic error in tau0 near the collapse boundary could change Table 1 without changing the qualitative direction. The single MW-like host with no quoted uncertainty on the fractions is a minor additional limitation.\n\nOn balance, the central claim holds up. The parametric model is a reasonable tool and the authors flag its limitations themselves, but the quantitative fractions should be treated as model-dependent estimates until the model is validated for WSIDM. The paper deserves a serious referee; I would press on the Appendix C discrepancy and ask for a sensitivity test around the tau0 > 0.75 threshold. I would bring it to reading group and would cite it.","headline":"First simulations showing P(k) suppression can weaken or erase SIDM core collapse; the qualitative result is solid, but the headline collapse fractions lean on a parametric model the paper itself flags as untested for this regime.","tokens_in":33890,"tokens_out":2078,"would_cite":true,"duration_ms":20496,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"Suppressing the initial power spectrum in a self-interacting dark matter model cuts the predicted fraction of core-collapsed dwarf-mass halos from 18% to as low as 2%, with the strongest suppression almost erasing core collapse in…","keywords":["self-interacting dark matter","warm dark matter","power spectrum suppression","gravothermal core collapse","cosmological zoom-in simulations","Milky Way dwarf satellites","dark acoustic oscillations","subhalo mass function"],"falsifier":"Run direct SIDM simulations of the same $T_{\\rm kd}=0.72$ keV initial conditions using the full scattering implementation rather than the analytical collapse recipe, and count halos above $10^8\\,M_\\odot$ that reach central densities exceeding their initial values; a fraction far above the predicted 2% would refute the claim that strong power-spectrum suppression erases core collapse.","tokens_in":32852,"feed_emoji":"🌌","tokens_out":16627,"duration_ms":130507,"temperature":0.7,"pith_summary":"The paper sets out to show that self-interacting dark matter (SIDM) models must include the power-spectrum suppression that naturally accompanies the same dark-sector physics, because that suppression removes much of SIDM's most distinctive signature. Using zoom-in simulations of a Milky Way–like halo, it finds that the fraction of core-collapsed subhalos above $10^8\\,M_\\odot$ drops from 18% when SIDM is added to cold initial conditions to 2%, 8%, and 17% when the initial power spectrum is suppressed at three warm-dark-matter-like levels; isolated halos drop from 13% to 2%, 2%, and 4%. The strongest suppression, which saturates current warm dark matter constraints, almost entirely erases core collapse in isolated halos. A sympathetic reader would care because core collapse in low-mass halos is a leading SIDM explanation for the dense and diverse inner densities of Milky Way dwarf satellites, and these results say that explanation can vanish when the model's early-Universe physics is included consistently.","feed_headline":"Power-spectrum suppression cuts core collapse from 18% to 2%","feed_subtitle":"Warm-dark-matter-like cutoffs delay halo growth, so fewer dwarf-mass halos reach the core-collapse stage.","key_machinery":"The load-bearing tool is a parametric gravothermal model developed in earlier work, which predicts SIDM density-profile evolution from a halo's CDM $V_{\\max}$ and $R_{\\max}$ histories. The paper applies it to matched CDM and $T_{\\rm kd}$-only simulations to compute the collapse timescale parameter $\\tau_0=\\int_{t_f}^{t_0} dt/t_c(t)$, with $\\tau_0<0.15$ meaning core formation and $\\tau_0>0.75$ meaning core collapse; systems are clipped at $\\tau_0=1.1$ because the model is validated only to that point. The same machinery, weighted by effective warm-dark-matter mass functions, separates the two causes of reduced collapse: low-mass halos that never form versus halos whose delayed, suppressed growth leaves them in the core-forming stage. The underlying WSIDM model is a 0.1 GeV dark-matter particle interacting through an 8.11 keV dark photon that also couples to a dark fermion, which sets the $P(k)$ cutoff through the kinetic decoupling temperature $T_{\\rm kd}$.","core_discovery":"On its own terms, the paper's discovery is that warm self-interacting dark matter (WSIDM) — a model with velocity-dependent SIDM plus a linear power-spectrum cutoff — changes both the abundances and the internal structure of dwarf-mass halos, and that the two effects are coupled through halo growth histories. The (sub)halo mass function suppression is set almost entirely by the $P(k)$ cutoff, while self-interactions set the density-profile evolution; however, the collapse driven by self-interactions is throttled by the same cutoff, because halos that form late and grow slowly have lower concentrations and longer gravothermal collapse timescales. Quantitatively, the core-collapsed fraction above $10^8\\,M_\\odot$ falls from 18% (subhalos) and 13% (isolated halos) in SIDM with CDM initial conditions to 2%/8%/17% and 2%/2%/4% in WSIDM with kinetic decoupling temperatures $T_{\\rm kd}=0.72$, 1.46, and 2.32 keV. In the most suppressed model the core-collapse signature in isolated halos is almost entirely erased, and in milder models the surviving collapse is accompanied by an increased number of extremely low-concentration isolated halos. These are the first WSIDM simulations to capture the full range of gravothermal evolution, including core collapse.","pith_inferences":["A consequence left implicit is that the collapse fraction may be a more sensitive small-scale-structure observable than the halo mass function: even the mildest cutoff here changes the isolated-halo collapse fraction by a factor of three while suppressing abundances by only a few percent at $10^8\\,M_\\odot$.","The paper's three cutoffs bracket the transition; one could interpolate collapse fraction versus $T_{\\rm kd}$ and use it as a likelihood for future dwarf surveys, which the paper motivates but does not construct.","The paper mentions low-concentration isolated halos as potential dark-matter-only counterparts of gas-rich ultradiffuse galaxies; testing that link requires baryonic simulations that include gas and star formation, which are not part of this work."],"forward_implications":["In WSIDM, (sub)halo mass-function suppression relative to CDM is set by the $P(k)$ cutoff, not by self-interactions, so abundance measurements directly probe the early-Universe side of the model.","Core-collapsed fractions among resolved dwarf-mass halos are a sensitive probe of the cutoff: even the mildest simulated cutoff ($T_{\\rm kd}=2.32$ keV) reduces the isolated-halo collapse fraction by roughly a factor of three.","Because stronger self-interactions in this model imply stronger $P(k)$ suppression, the core-collapse signature self-regulates; observations of both abundances and density profiles are needed to break the degeneracy.","WSIDM with mild suppression preserves a sizable collapsed subhalo population while adding low-concentration isolated halos, giving a discovery signature for upcoming strong-lensing and satellite-population data.","The central density–pericenter anticorrelation seen among Milky Way satellites is reproduced by the $T_{\\rm kd}=0.72$ and 1.46 keV WSIDM runs, which contain both cored and collapsing subhalos, while a velocity-independent SIDM that never collapses cannot."],"supporting_citations":[{"why":"Defines the MilkyWaySIDM velocity-dependent cross section and the SIDM scattering implementation whose CDM-initial-condition core-collapsed fractions (13% isolated, 18% subhalos) serve as the baseline.","marker":"Yang et al. (2023)"},{"why":"Supplies the parametric gravothermal model used to compute $\\tau_0$ and the collapse fractions from CDM and $T_{\\rm kd}$-only simulations, including the $\\tau_0=0.15$ and $0.75$ thresholds and the validation claim.","marker":"Yang et al. (2024, 2025)"},{"why":"Presents the earlier simulations that combined $P(k)$ suppression with SIDM but had suppression too strong for core collapse, providing the comparison case this work extends.","marker":"Vogelsberger et al. (2016)"},{"why":"Supplies the dark-photon–dark-fermion Lagrangian and the kinetic decoupling temperature relation that set the WSIDM model parameters and $P(k)$ cutoff scales.","marker":"Huo et al. (2018)"},{"why":"Provides the modified CAMB transfer-function machinery used to generate the $T_{\\rm kd}$ power spectra and dark acoustic oscillation initial conditions.","marker":"Cyr-Racine et al. (2016)"},{"why":"Describes the zoom-in setup, initial-condition generation, the Halo004 Milky Way–like host, and the warm-dark-matter (sub)halo mass-function suppression fit used to reweight SIDM collapse statistics.","marker":"Paper I"}],"fun_headline_variants":["Suppressed power spectrum throttles SIDM core collapse","Simulations: power-spectrum cutoff reduces dark halo collapse","Dark matter core collapse quenched by power-spectrum suppression","P(k) suppression silences SIDM core collapse in dwarfs"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The prediction of specific collapsed fractions depends on a fast analytical recipe for gravothermal collapse, which was tested on ordinary cold SIDM but not on the suppressed-initial-condition runs it is here applied to, and on one Milky Way-like host standing in for all such systems.","fun_headline_variants_meta":{"raw":{"variants":["Suppressed power spectrum throttles SIDM core collapse","Simulations: power-spectrum cutoff reduces dark halo collapse","Dark matter core collapse quenched by power-spectrum suppression","P(k) suppression silences SIDM core collapse in dwarfs"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001332,"raw_usage":{"total_tokens":5539,"prompt_tokens":1186,"completion_tokens":4353,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":802,"completion_tokens_details":{"reasoning_tokens":4283}},"tokens_in":802,"tokens_out":4353,"duration_ms":33186,"temperature":1.0,"reasoning_tokens":4283,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T13:27:43.332316+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Run direct SIDM simulations of the same $T_{\\rm kd}=0.72$ keV initial conditions using the full scattering implementation rather than the analytical collapse recipe, and count halos above $10^8\\,M_\\odot$ that reach central densities exceeding their initial values; a fraction far above the predicted 2% would refute the claim that strong power-spectrum suppression erases core collapse.","supporting_citations":[{"cited_title":"2018, http://dx.doi.org/10.1016/j.physletb.2018.06.024 Physics Letters B , 783, 76","cited_arxiv_id":null,"evidence_quote":"Supplies the dark-photon–dark-fermion Lagrangian and the kinetic decoupling temperature relation that set the WSIDM model parameters and $P(k)$ cutoff scales."}],"review_version":1}