{"id":"c4b7e156-c077-472b-9dcf-e1dfe7bb155b","arxiv_id":"2506.06049","paper_version":2,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"From 1D MESA simulations with spherically symmetric energy injection, the authors derive crude negative jet feedback coefficients chi_AGB ≈ 0.5 (M2/0.1 M_sun)^-1 and chi_RGB ≈ 0.8 (M2/0.1 M_sun)^-1.","lead":"This paper uses simplified one-dimensional stellar simulations to estimate how much jets from a low-mass companion star reduce the density and accretion power inside the envelope of a giant star during a common envelope phase. The authors propose simple scaling laws for AGB and RGB primaries that could be used in future population synthesis models of planetary nebula progenitors.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 1D feedback curves are derived from constant-ζ runs, but physical jets must satisfy ζ=ηξχ; this over-injects energy and likely biases χ low, undermining Eqs. (8)-(9).","rationale":"The reader's weakest_assumption is that 1D spherical energy deposition reproduces the density reduction of real bipolar jets. That is a valid and explicitly acknowledged limitation, but it is not the most load-bearing issue. The primary quantitative result, Eqs. (8) and (9), depends on an internal step that appears inconsistent even within the 1D model: the simulations use a constant ζ, while the feedback relation ζ = ηξχ requires ζ to decrease as χ decreases. The constant-ζ runs therefore inject more energy than a self-consistent feedback loop would, likely overestimating the envelope expansion and underestimating χ. This bias is unacknowledged in the paper, and it is not addressed by the comparison with Hillel et al. (2022), which also uses constant-ζ power-injection runs in 1D and 3D. The qualitative conclusion that jets reduce the envelope density is robust, and the paper is transparent about the crudeness of its estimates, so a conditional acceptance remains appropriate. However, the derivation of the quantitative coefficients should be re-examined; a self-consistent 1D run is cheap and would settle whether the bias is significant. If the bias is large, Eqs. (8) and (9) should be revised or explicitly labeled as upper limits on the feedback strength.","tokens_in":14915,"tokens_out":10941,"duration_ms":108456,"concrete_test":"Run a modified 1D MESA calculation for the AGB model with M2 = 0.2 Msun in which the injected energy is updated self-consistently each timestep: compute χ(t) from the density at the companion's current radius, set ζ(t) = ηξχ(t) with a representative ηξ = 0.15, and follow the inspiral to a = 0.2 R0. Compare the final ρ/ρ0 at the companion's radius with the value predicted by inverting Eq. (8) for the same ηξ. If the self-consistent χ is, say, > 0.8 while Eq. (8) predicts ~0.5, the constant-ζ method systematically overstates the negative feedback; repeat at ηξ = 0.05 and 0.25 to bracket the range.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The most load-bearing problem is not the acknowledged 1D spherical geometry but an unacknowledged inconsistency in the feedback loop. In the MESA runs, the jet power is injected at a fixed, prescribed ζ (Eq. 6), and the final density reduction χ(ζ) is read off at the end of the inspiral (Section 3). The right panels of Figures 3-4 then identify a physical solution by plotting χ against ηξ = ζ/χ and reading off χ for the 'expected' range ηξ ≈ 0.05-0.25. But in the physical negative-feedback cycle, ζ is not a free constant: Eq. (5) defines ζ = ηξχ, so as the envelope density drops and χ < 1, the jet power must drop with it. A correct 1D feedback run would inject energy with ζ(t) = ηξχ(t), using the density at the companion's current radius to update the accretion rate and jet power every timestep. The constant-ζ runs instead deposit energy proportional to the unperturbed BHL rate for the whole inspiral. Since χ(t) < 1 after the first timestep, the constant-ζ runs inject more energy than the physical feedback loop, over-inflate the envelope, and produce χ values that are systematically too small (i.e., the negative feedback is overestimated). Equations (8) and (9) are then not the fixed points of the actual feedback dynamics but fixed points of an over-driven response function. The magnitude of the bias is unknown but could be large; for example, the AGB fit used to get Eq. (8) is anchored to ζ ≤ 0.016 runs in which the injected power never weakens as the density falls.","agreement_with_reader":"disagree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper uses the 1D stellar evolution code MESA to model the negative jet-feedback mechanism in common envelope evolution of AGB and RGB stars with low-mass main-sequence companions (M2 = 0.1–0.2 M_sun). Energy is deposited into a spherical shell to mimic the effect of jets, and the resulting envelope density reduction chi = rho/rho0 is measured at three radii for a set of fixed values of the dimensionless parameter zeta. The authors fit chi(zeta), transform to the plane chi versus eta xi = zeta/chi, extrapolate to the range eta xi ~ 0.05–0.25, and propose the central results chi_AGB ~ 0.5 (M2/0.1 M_sun)^{-1} and chi_RGB ~ 0.8 (M2/0.1 M_sun)^{-1}, given in Eqs. (8) and (9). The method intentionally neglects orbital energy and uses spherical energy deposition despite the intrinsically non-spherical jet-envelope interaction.","tokens_in":15290,"tokens_out":11626,"duration_ms":112148,"significance":"If Eqs. (8) and (9) were reliable, they would provide a simple and useful parametrization of jet feedback for population-synthesis studies of planetary-nebula progenitors and for interpreting luminous red novae and grazing envelope evolution. The paper is transparent about several limitations, including the 1D spherical symmetry and the neglect of orbital energy, and it clearly shows the raw data and fits in Figures 3 and 4. However, the quantitative result is not currently supported: the simulations do not implement the negative feedback loop self-consistently, the main coefficients come from a large extrapolation without error estimates, and the transfer of 1D spherical results to real bipolar jets is not independently validated. The paper is a useful first step, but it needs substantial additional work before Eqs. (8) and (9) can be used as quantitative input.","major_comments":[{"comment":"The negative feedback loop is not actually closed in the simulations. Equation (5) defines zeta = eta xi chi, where chi is the density-reduction factor, but the MESA runs treat zeta as a constant input parameter and inject energy according to Eq. (6) using the unperturbed density rho0. In the physical cycle, once the envelope density drops (chi < 1), the accretion rate and hence the jet power should drop with it, so zeta should be time-dependent: zeta(t) = eta xi chi(t). A constant-zeta run over-injects energy throughout the inspiral, over-inflates the envelope, and therefore biases chi systematically low. The transformation to eta xi = zeta/chi in the right panels of Figures 3 and 4 does not repair this, because the response function itself has been computed under an over-driven perturbation rather than at the fixed point of the feedback dynamics. Equations (8) and (9) are thus biased; the size of the bias is unknown but could be substantial, since the fits are anchored to runs with zeta <= 0.016-0.019 in which the injected power never weakens as the density falls.","section":"Section 2.2 and Section 2.4"},{"comment":"The primary result is an extrapolation, not a measurement. The simulations reach zeta <= 0.016 (AGB) and zeta <= 0.019 (RGB), while the inferred target range eta xi ~ 0.05-0.25 with the quoted chi values corresponds to zeta ~ 0.005-0.1, i.e., a factor of several up to roughly an order of magnitude above the simulated range. The linear and log-linear fits give noticeably different extrapolated values, no error bars are reported for the fits, and points with chi > 1 at the outer radius are excluded by a criterion applied after the fits were made. The authors honestly acknowledge the extrapolation, but the precision implied by Eqs. (8) and (9) is not supported by the data.","section":"Section 3"},{"comment":"The transfer of the 1D spherical energy-deposition results to real bipolar jets is not established. The paper itself states in Section 5 that the jet-envelope interaction is highly non-spherical, and the only quantitative support offered is the agreement between the 1D Grichener et al. (2021) and 3D Hillel et al. (2022) neutron-star-in-red-supergiant calculations, which share the same group's setup and assumptions and concern a different accretor mass and envelope regime. That agreement does not validate the 1D approach for a 0.1-0.2 M_sun main-sequence companion inside an AGB or RGB envelope, where the cocoon geometry and feedback efficiency are likely different. Therefore, even a fully self-consistent 1D calculation would not by itself establish that Eqs. (8) and (9) apply to real systems.","section":"Section 5"},{"comment":"The M2 dependence in Eqs. (8) and (9) is derived by scaling, not by direct simulation. Section 3 assumes M2/R2 is approximately constant for low-mass main-sequence stars and rescales zeta by M2^{-2} (so eta xi scales as M2^{-2} for a fixed chi) to convert the M2 = 0.2 M_sun runs to M2 = 0.1 M_sun. This assumes that the envelope response depends only on the absolute injected power and not on the companion mass separately. No M2 = 0.1 M_sun simulation is shown, so the inverse-linear scaling in Eqs. (8) and (9) is not directly tested.","section":"Section 3"}],"minor_comments":[{"comment":"In the RGB run description, \"zeta = 0.19\" should be \"zeta = 0.019\", consistent with the stated numerical limit and with Figure 2.","section":"Section 3"},{"comment":"The caption contains a duplicated word: \"by a factor of of 2.3\" should read \"by a factor of 2.3\".","section":"Figure 1"},{"comment":"The captions refer to \"M1 = 0.1 M_sun\" where the companion mass M2 is meant; this should be corrected in both figure captions.","section":"Figure 3"},{"comment":"Adding error bars or a quantitative estimate of the fit uncertainty to the left panels of Figures 3 and 4 would substantially strengthen the paper, especially because the result depends on extrapolation.","section":"Section 3"}],"recommendation":"major_revision","confidential_remarks":"The paper is part of a series by this group, and the central quantitative claim is not yet ready for acceptance. The most important issue is the lack of a self-consistent feedback loop in the simulations: fixed-zeta runs over-inject energy because zeta should decrease as chi drops. I would ask the authors to either implement time-dependent zeta(t) = eta xi chi(t) in the energy-injection scheme, or to provide a quantitative bracketing estimate of the bias introduced by constant zeta. I would also request that the extrapolation be presented with explicit uncertainty bands and that the M2 scaling be tested with at least one direct M2 = 0.1 M_sun run. The paper's strengths are its clear statement of limitations and its useful framing of the problem, but the specific numerical coefficients should not be quoted as established until these issues are addressed."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"What should you know? This is a typical Soker-group exploratory paper: straightforward 1D MESA experiments, transparent about limitations, and proposing simple scaling laws for jet negative feedback in CEE. The new bit is applying the energy-injection method to main-sequence companions in AGB and RGB envelopes and deriving chi proportional to M2^-1. That is a useful step; population synthesis and CEE simulators can grab Eqs. (8)-(9) and plug them in.\n\nThe paper is honest about its crudeness: spherical symmetry, hydrostatic equilibrium, no orbital energy, extrapolation beyond the simulated zeta range. It also gives credit by comparing with Grichener et al. (2021) and Hillel et al. (2022) for neutron star companions, which supports the 1D method in that regime.\n\nBut the load-bearing problem is not in the acknowledged list. The simulations inject energy at constant zeta, while the physical negative feedback loop requires zeta = eta*xi*chi to drop as the envelope density drops. After the first timestep, chi<1, so constant-zeta runs deposit more energy than the self-consistent loop, over-inflate the envelope, and push chi down. The paper then maps chi onto eta*xi = zeta/chi and reads off the 'physical' point, but that point is the response of an over-driven system, not a fixed point of the actual dynamics. The magnitude of the bias is unknown but likely not small: the AGB fit is anchored to zeta <= 0.016 runs, and the extrapolation to eta*xi ~ 0.15 involves zeta values 3-6 times larger than any simulated run. The paper also excludes chi>1 points post hoc and gives no error bars on the fits.\n\nThe qualitative conclusion that jets reduce the density and therefore regulate accretion is almost certainly correct. The specific scaling in Eqs. (8)-(9) should be treated as provisional. The right fix is a 3D simulation with self-consistent energy injection, or at least a 1D run where zeta(t) = eta*xi*chi(t) is updated each timestep. The authors themselves call for 3D work, so this is consistent with their own caveats, but they don't flag the constant-zeta inconsistency.\n\nWho is this for? CEE and planetary nebula researchers, especially those doing population synthesis or looking for a simple feedback prescription. It deserves a serious referee; I would send it out. The ideal referee report would ask for a self-consistent feedback run or a clear argument why the constant-zeta response curve is transferable, plus error bars and a less post hoc selection.","headline":"Useful first estimate of negative jet feedback for low-mass companions in CEE, but the headline chi scaling is biased by constant-zeta energy injection that ignores the feedback loop's own power reduction.","tokens_in":15846,"tokens_out":3121,"would_cite":true,"duration_ms":31373,"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":"A low-mass companion's jets inside a giant's envelope cut the local envelope density, and therefore their own power, by a factor roughly $\\chi_{\\rm AGB} \\simeq 0.5\\,(M_2/0.1\\,M_\\odot)^{-1}$ for AGB stars and $\\chi_{\\rm RGB} \\simeq…","keywords":["jets","common envelope evolution","negative jet feedback","asymptotic giant branch stars","red giant branch stars","planetary nebulae","Bondi-Hoyle-Lyttleton accretion","luminous red novae"],"falsifier":"A three-dimensional hydrodynamic simulation of a $0.2\\,M_\\odot$ main-sequence companion with jets spiraling inside an AGB envelope, and a separate run for an RGB envelope, run until the companion reaches about twenty percent of the stellar radius, measuring the density at the companion's orbit and comparing it with the unperturbed profile; if the measured $\\chi$ at $\\eta\\xi \\simeq 0.15$ falls outside roughly $0.1$–$0.4$ for the AGB case or $0.3$–$0.7$ for the RGB case, the one-dimensional transfer and its extrapolation fail.","tokens_in":14646,"feed_emoji":"🔭","tokens_out":8885,"duration_ms":80969,"temperature":0.7,"pith_summary":"The paper asks how much a low-mass companion's jets throttle themselves when the companion spirals inside the envelope of an AGB or RGB star during common envelope evolution. The jets heat and inflate the surrounding envelope, which lowers the local gas density; because the accretion rate that feeds the jets depends on that density, the jets reduce their own power. Using one-dimensional stellar evolution runs with energy deposited in the outer envelope as a stand-in for jet heating, the paper finds that for a main-sequence companion of mass $M_2 = 0.1$–$0.2\\,M_\\odot$ the density, accretion rate, and jet power are all reduced by a factor $\\chi_{\\rm AGB} \\simeq 0.5\\,(M_2/0.1\\,M_\\odot)^{-1}$ in AGB envelopes and $\\chi_{\\rm RGB} \\simeq 0.8\\,(M_2/0.1\\,M_\\odot)^{-1}$ in RGB envelopes, at mid-range assumptions for the accretion efficiency and jet energy fraction. These formulas are offered as crude input for future three-dimensional simulations and population studies. The motivation is that jet-shaped planetary nebulae and their central binaries are widely thought to descend from common envelope evolution, and the same jet feedback may power luminous red novae.","feed_headline":"Jets cut their own power by half inside AGB envelopes","feed_subtitle":"Stellar models quantify how jets thin the envelope that feeds them, shaping planetary nebulae and powering red novae.","key_machinery":"The machinery is a one-dimensional stellar evolution model in which the energy of two opposite jets is deposited, at each timestep, into a thick spherical shell of the giant's outer envelope according to the jet-power formula $\\dot E_{2j} = 2\\pi\\zeta G M_2^3 a^2 \\rho_0 / (M^2 R_2) \\sqrt{G(M+M_2)/a}$, with $\\zeta = \\eta\\xi\\chi$ combining the accretion-efficiency fraction, the jet-energy fraction, and the density-reduction factor. The central measured quantity is $\\chi = \\rho/\\rho_0$ at the companion's orbital radius, which closes the feedback loop by entering both the accretion rate $\\dot M_{\\rm acc} = \\chi\\xi\\dot M_{\\rm BHL,0}$ and the jet power. The method follows an earlier neutron-star common-envelope study and is checked against a three-dimensional run in a lower-power regime, whose results lie on the same linear fit.","core_discovery":"On the paper's own terms, the central claim is that the negative jet feedback coefficient $\\chi \\equiv \\rho/\\rho_0$ — the factor by which jets lower the envelope density near their launching companion — is approximately $\\chi_{\\rm AGB} \\simeq 0.5\\,(M_2/0.1\\,M_\\odot)^{-1}$ for AGB progenitors and $\\chi_{\\rm RGB} \\simeq 0.8\\,(M_2/0.1\\,M_\\odot)^{-1}$ for RGB progenitors of planetary nebulae. The calculation takes the actual accretion rate to be a fraction $\\xi \\approx 0.2$–$0.5$ of the Bondi-Hoyle-Lyttleton rate and lets the jets carry a fraction $\\eta \\approx 0.25$–$0.5$ of the accretion energy, giving the jet power that is deposited into the envelope. Because the code could not converge for the highest expected jet powers, the quoted values are extrapolations from runs at lower energy-injection rates, and the paper explicitly calls them crude estimates that await three-dimensional simulation.","pith_inferences":["A direct 3D run with a main-sequence companion, not a neutron star, would settle whether the spherical energy-deposition approximation over- or under-estimates the local density reduction; if real jets carve low-density channels that let accretion continue, equations (8) and (9) may underestimate $\\chi$.","If the extrapolation from the numerically accessible low-$\\zeta$ runs saturates rather than remaining linear, the negative feedback would be weaker than equations (8) and (9) imply, making jet power during CEE larger than these estimates; light-curve shapes of luminous red novae could constrain this.","Population synthesis using these coefficients could predict a systematic trend: more massive companions thin the envelope more strongly, so they should end common envelope evolution with a different mass-accretion history than lighter companions, a trend testable against the masses of main-sequence stars in post-CEE planetary nebula cores."],"forward_implications":["For low-mass main-sequence companions, jets can cut their own power by roughly a factor of two to four depending on companion mass, so accretion during early common envelope evolution is self-regulated rather than run-away.","Equations (8) and (9) give population-synthesis studies a ready-made negative-feedback coefficient to apply when modelling how much mass the companion accretes and how much energy jets deposit during CEE.","Because the same method used here was found to agree with a 3D run for a neutron-star companion, the paper expects the 1D energy-deposition approach to be a useful first step before fully 3D common-envelope jet simulations.","The orbital energy deposited by the spiraling companion can be neglected for these low masses down to separations of roughly $40\\,R_\\odot$ (AGB) and $25\\,R_\\odot$ (RGB), which supports modelling the early CEE phase with jets only.","Self-regulated jet power of this kind is a candidate energy source for luminous red novae and for shaping planetary nebulae during grazing envelope evolution."],"supporting_citations":[{"why":"Supplies the 1D energy-deposition method and the neutron-star analogue whose 3D comparison validates the approach.","marker":"Grichener et al. (2021)"},{"why":"3D runs of a neutron star in a red supergiant envelope that fall on the same linear fit as the 1D runs, the main quantitative support for transferring 1D results to real jets.","marker":"Hillel et al. (2022)"},{"why":"High-quality 3D simulations giving accretion efficiency xi ~ 0.5, the anchor for the assumed range xi ~ 0.2-0.5.","marker":"Kashi et al. (2022)"},{"why":"3D common-envelope simulations showing jets inflate a low-density cocoon that lowers the accretion rate, defining the negative feedback channel modelled here.","marker":"Chamandy et al. (2018)"},{"why":"Source for lower BHL accretion efficiencies in steep density gradients, widening the adopted xi range downward.","marker":"MacLeod & Ramirez-Ruiz (2015)"},{"why":"The stellar evolution code in which the AGB and RGB models are built and the jet energy is injected.","marker":"Paxton et al. 2011, 2013, 2015, 2018, 2019; Jermyn et al. 2023"},{"why":"Review that defines positive and negative jet feedback and frames the mechanism this paper quantifies.","marker":"Soker (2016)"}],"fun_headline_variants":["Jets reduce their own power by half in AGB envelopes","Stellar jets starve themselves in common envelope evolution","Jets cut their own fuel supply in stellar envelopes","Astrophysical jets self-limit by halving their own power","Common envelope jets throttle their own power in models"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is that depositing the jets' energy as spherically symmetric heat in a one-dimensional stellar model reproduces the density reduction that real bipolar, off-center jets cause around the companion; the paper states this limitation directly, and its only quantitative support is the agreement between one- and three-dimensional runs for a neutron-star companion in a different mass regime.","fun_headline_variants_meta":{"raw":{"variants":["Jets reduce their own power by half in AGB envelopes","Stellar jets starve themselves in common envelope evolution","Jets cut their own fuel supply in stellar envelopes","Astrophysical jets self-limit by halving their own power","Common envelope jets throttle their own power in models"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000749,"raw_usage":{"total_tokens":3370,"prompt_tokens":1012,"completion_tokens":2358,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":628,"completion_tokens_details":{"reasoning_tokens":2278}},"tokens_in":628,"tokens_out":2358,"duration_ms":18689,"temperature":1.0,"reasoning_tokens":2278,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-07T06:01:34.911337+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A three-dimensional hydrodynamic simulation of a $0.2\\,M_\\odot$ main-sequence companion with jets spiraling inside an AGB envelope, and a separate run for an RGB envelope, run until the companion reaches about twenty percent of the stellar radius, measuring the density at the companion's orbit and comparing it with the unperturbed profile; if the measured $\\chi$ at $\\eta\\xi \\simeq 0.15$ falls outside roughly $0.1$–$0.4$ for the AGB case or $0.3$–$0.7$ for the RGB case, the one-dimensional transfer and its extrapolation fail.","supporting_citations":[{"cited_title":"2022, , 516, 3193, 10.1093/mnras/stac1912","cited_arxiv_id":null,"evidence_quote":"High-quality 3D simulations giving accretion efficiency xi ~ 0.5, the anchor for the assumed range xi ~ 0.2-0.5."}],"review_version":1}