Pith. sign in

REVIEW 2 major objections 6 minor 84 references

Kaon condensation can make the HESS J1731–347 compact object small and light, but it cools the star too fast to match its observed temperature.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗

Kaon-condensed equations of state that fit HESS J1731–347’s mass and radius overcool the star, so they cannot also match its high surface temperature.

T0 review reviewed 2026-07-31 challenge →

load-bearing objection Clean negative result: the same kaon EoSs that hit the HESS J1731–347 M–R box overcool it for every pairing/envelope combo they tried. the 2 major comments →

arxiv 2607.28107 v1 pith:QNYCD7RL submitted 2026-07-30 astro-ph.HE astro-ph.GAastro-ph.SRnucl-th

Impact of Kaon Condensation on the Thermal Evolution of the CCO in HESS J1731--347 Supernova Remnant

D.G. Nanopoulos , P.S. Koliogiannis , V. Petousis , M. Veselsky , Ch.C. Moustakidis This is my paper
classification astro-ph.HE astro-ph.GAastro-ph.SRnucl-th
keywords neutron star coolingkaon condensationHESS J1731-347central compact objectequation of statedirect Urcanucleon superfluidityneutrino emissivity
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The central compact object in HESS J1731–347 looks both unusually light and small and still relatively hot at a few thousand years of age. Soft equations of state with negatively charged kaon condensation can reproduce that compactness. This paper asks whether the same models can also keep the star warm enough. They cannot: once kaons appear, fast neutrino processes turn on, proton pairing is largely quenched in the condensed core, and the surface temperature drops well below the observed range at the inferred age. Within the cooling framework used here, kaon condensation therefore fails as a joint structural-and-thermal explanation, tightening the set of compositions still allowed for this object.

Core claim

Negatively charged kaon condensation softens the equation of state enough to match the low mass and small radius reported for the CCO in HESS J1731–347, but the same condensation activates efficient neutrino emission (direct Urca plus kaon-induced Urca channels) and eliminates proton superfluidity in the condensed core, driving the redshifted surface temperature substantially below the observationally inferred range at 2–6 kyr. Within the adopted cooling framework, kaon condensation cannot account for both properties at once.

What carries the argument

Kaon-condensed equations of state (MDI+APR1-KC1/KC2) coupled to the isothermal cooling balance: onset of kaons opens fast dURCA and n-/p-kURCA neutrino channels while pushing the proton Fermi momentum outside the 1S0 pairing window, so the enhanced emissivities are only weakly suppressed.

Load-bearing premise

The result hinges on proton pairing dying out almost as soon as kaons appear; if protons stayed paired deep in the condensed core, the fast cooling could be suppressed enough to keep the star warm.

What would settle it

Re-run the same mass–radius configurations with microscopically motivated proton-pairing gaps that remain open throughout the kaon-condensed core; if any such model then lands inside the observed temperature box at 2–6 kyr, the thermal exclusion fails.

Watch this falsifier. Get emailed when new claim-graph text bears on it.

If this is right

  • Kaon-condensed stars that fit the HESS J1731–347 mass–radius box are thermally ruled out under standard pairing and envelope assumptions.
  • Joint mass–radius–temperature constraints exclude this exotic phase more tightly than structure alone.
  • Hadronic or other exotic interpretations that avoid fast Urca-like channels remain viable for this object.
  • Future cooling work on kaon matter must prioritize proton pairing that can survive high proton density.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If proton pairing at high density remains theoretically unsettled, the thermal veto on kaon stars is provisional rather than definitive.
  • The same fast-cooling logic would likely apply to other soft exotic cores (e.g., pion condensates) that raise the proton fraction and open direct Urca-like channels.
  • A confirmed young, hot, low-mass CCO is a sharper filter on dense-matter composition than mass and radius alone.
Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

2 major / 6 minor

Summary. The manuscript examines whether negatively charged kaon condensation can simultaneously explain the low mass and small radius inferred for the CCO in HESS J1731–347 and its relatively high redshifted surface temperature at an age of 2–6 kyr. Using chiral-effective-model EoSs coupled to MDI+APR1 (with two values of a3ms), the authors show that kaon-condensed configurations can cross the Doroshenko et al. mass–radius region (Fig. 1, Table II). They then compute isothermal cooling including dURCA, modified Urca, bremsstrahlung, PBF, and the kaon-induced Urca channels (Table I), with 18 combinations of 1S0 proton and 3P2 neutron pairing models and both Fe- and He-like envelopes. The same kaon-driven rise in proton fraction that softens the EoS activates fast neutrino emission and drives Tcp to zero inside the condensate (Figs. 3b, 4b), so that all kaon-condensed cooling tracks fall well below the observational T∞s box (Figs. 5b, 6). The purely hadronic comparison case can match the thermal data with a light-element envelope. The authors conclude that, within the adopted cooling framework, kaon condensation cannot account for both the structural and thermal properties of the source.

Significance. The result is a clean, scoped negative constraint on an exotic interpretation that had been advanced on structural grounds alone. Combining M–R and cooling for the same EoS family is the right methodology for this object, and the systematic scan over pairing models, envelope compositions, and two a3ms values makes the thermal exclusion more than a single-track illustration. The claim is carefully limited to the adopted framework and is falsifiable by future microscopic proton gaps that remain finite at the higher pFp of the condensate—an avenue the authors themselves flag. Negative results of this type are useful for the HESS J1731–347 literature and for dense-matter cooling more generally.

major comments (2)
  1. [Section III; Figures 3b, 4b; Section IV] §III and Figs. 3b, 4b: The vanishing of 1S0 proton pairing throughout the kaon-condensed core is load-bearing for the rapid cooling. Every gap model taken from Andersson et al. (via Ref. [64]) has Tcp drop to zero once kaons appear, so the fast dURCA and kURCA channels are only weakly suppressed there. The conclusion is correctly scoped to this framework, and §IV already lists alternative proton pairing as future work. To make the robustness statement quantitative rather than qualitative, the manuscript should add a short estimate of the residual emissivity suppression (or effective Tcp) that would be required to keep T∞s inside the 2–6 kyr observational box. That bound can be obtained from the existing cooling infrastructure without new microscopic gap calculations and would substantially strengthen the central claim.
  2. [Section II.C; Table I; Figures 5b, 6] §II.C, Table I, and the cooling results in Figs. 5b and 6: The accelerated cooling is attributed jointly to dURCA (reduced by cos²(θ/2)), n-kURCA, and p-kURCA, but the paper never shows the radial profile of the condensate amplitude θ nor the fractional contribution of each fast channel to L∞ν. Because the relative weights depend on θ and on the local Fermi momenta, a brief luminosity decomposition (or a supplementary figure of θ(r) and channel-by-channel emissivities for one representative configuration) is needed to establish which process actually dominates the thermal exclusion. Without it, the reader cannot judge how sensitive the conclusion is to the precise kURCA rate formulae versus the mere opening of nucleonic dURCA in the condensate.
minor comments (6)
  1. [Abstract] Abstract: “soften the equation of state and facilitate” → “softens … and facilitates” (subject–verb agreement).
  2. [Figures 2–4] Figures 2–4: The pairing-model labels (hnt, mnt, eps, fps, …) are taken from Table 1 of Ref. [64] but are never expanded in the captions or main text. A short legend or a pointer to the corresponding gap-model names would make the figures self-contained.
  3. [Figure 5] Figure 5 caption refers to “Ts1[K]” on the axis; this appears to mean the redshifted surface temperature T∞s. Using a consistent symbol (T∞s) in both the axis label and the caption would avoid ambiguity.
  4. [Section II.G] §II.G: The isothermal approximation is stated to become valid for t ≳ 10–10³ yr. Given that the observational age window starts at 2 kyr, a one-sentence remark that thermal relaxation is expected to be complete by the epoch of interest (or a citation to a non-isothermal check) would close a minor loophole for readers unfamiliar with the standard argument.
  5. [Section II.C] §II.C: The nucleon effective-mass ratio is fixed at m∗n,p = 0.7 m with no variation. A brief note that the qualitative conclusion (fast cooling once the condensate appears) is insensitive to this choice within the usual 0.6–0.8 range would be helpful, even if no extra runs are shown.
  6. [Title page] Author list / affiliations: minor spacing inconsistencies (e.g., “V . Petousis”, “Veselsk´y”) should be cleaned for the journal production version.

Circularity Check

0 steps flagged

No significant circularity: prior-group EoS is an input under test; cooling is an independent negative result against external T–age data.

full rationale

The paper’s load-bearing claim is a negative one: kaon-condensed EoSs that can hit the external HESS J1731–347 M–R box activate fast neutrino channels (dURCA, n-kURCA, p-kURCA) and drive T∞s well below the external 2–6 kyr temperature box for all 18 pairing×envelope combinations considered. The structural EoS is taken from the group’s earlier work (Ref. [35]), which is ordinary model input, not a uniqueness theorem or a fit to the thermal data being tested. Pairing gaps are taken from Andersson et al. (external), emissivities from the standard literature, and M, R, T∞s, and age are observational. Nothing in the cooling equations is fitted to the CCO temperature and then re-presented as a prediction; the calculation fails to match that temperature. Self-citation of the EoS framework therefore does not force the central claim by construction. Score 0; steps empty.

Axiom & Free-Parameter Ledger

4 free parameters · 6 axioms · 0 invented entities

The paper sits on a standard neutron-star cooling stack plus a group-specific kaon EoS. Load-bearing choices are the a3ms values that set kaon onset, the published nucleon gap parametrizations (especially proton 1S0), fixed effective masses, isothermal global cooling, and the observational age/temperature window. No new particle is invented here; kaon condensation is an existing exotic phase being stress-tested.

free parameters (4)
  • a3ms (kaon–nucleon coupling / proton strangeness) = -238 MeV (KC1), -260 MeV (KC2)
    Treated as free in [-134,-310] MeV; two representative values (-238 and -260 MeV) define KC1/KC2 and control condensate onset and abundance, hence which fast cooling channels open.
  • Nucleon effective-mass ratio m*_n,p / m = 0.7
    Fixed to 0.7 for emissivities and specific heats; directly scales dURCA/mURCA/PBF rates and heat capacity.
  • Pairing-gap shape parameters Δ0, k0–k3 for each 1S0/3P2 model = literature table values (model-dependent)
    Taken from Table 1 of Ref. [64]; choice among 18 model combinations controls where superfluid suppression operates and is decisive once kaons raise proton density.
  • Envelope composition (Fe-like vs He-like T_b–T_s relation) = Fe: Tb8=1.288(Ts6^4/gs14)^0.455; He: Tb8=0.552(Ts6^4/gs14)^0.413
    Two discrete phenomenological envelopes from Refs. [71,72]; changes surface temperature at fixed interior T and is varied rather than fitted, but remains an external choice the claim is tested against.
axioms (6)
  • domain assumption Cold β-equilibrated npe(K−) matter with neutrinos escaped; chemical equilibrium μn−μp=μe=μK− once kaons condense.
    Section II.A; standard catalyzed-matter assumption underlying the EoS and process thresholds.
  • domain assumption Isothermal redshifted core after thermal relaxation; cooling reduced to global heat-balance C dT∞/dt = −Lν∞ − Lγ∞.
    Section II.G; stated valid for t ≳ 10–10^3 yr, covering the 2–6 kyr age window used.
  • domain assumption Kaon contribution to specific heat is negligible; crustal specific heat neglected; only electron–nucleus bremsstrahlung added in the crust.
    Sections II.D and II.F citing [54,45,69,70].
  • domain assumption BCS singlet proton and triplet neutron pairing with published gap parametrizations and standard reduction factors; kURCA suppressed only by the single participating species’ gap.
    Section II.E; pairing models from [64]; kURCA suppression following [53,54].
  • domain assumption Observational anchors: M≈0.77 M⊙, R≈10.4 km, T_s^∞≈2.05 MK, age 2–6 kyr for HESS J1731–347.
    Introduction and Figs. 5–6; values from Doroshenko et al. and revised-age references [8,18,29,37–39].
  • ad hoc to paper Chiral effective model coupled to MDI+APR1 provides the baseline hadronic and kaon-condensed EoSs.
    Section II.B; microphysical EoS taken from the authors’ framework [35,42] rather than a community-wide standard set.

reviewed 2026-07-31 · how reviews work

0 comments
Cite this review

Pith. "Pith review of Impact of Kaon Condensation on the Thermal Evolution of the CCO in HESS J1731--347 Supernova Remnant." pith.science (2026). https://pith.science/paper/QNYCD7RL

@misc{pith2026260728107,
  author       = {Pith},
  title        = {Pith review of: Impact of Kaon Condensation on the Thermal Evolution of the CCO in HESS J1731--347 Supernova Remnant},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/QNYCD7RL}},
  note         = {Machine review of arXiv:2607.28107}
}
Share X Bluesky LinkedIn Reddit HN
read the original abstract

Recent analyses of the central compact object in the HESS J1731--347 supernova remnant suggest an unusual combination of a low mass and small radius, while its thermal emission indicates a relatively high surface temperature at its estimated age. Reconciling these structural and thermal properties within a unified theoretical framework may provide important constraints on the equation of state and composition of dense matter. In this work, we investigate the thermal consequences of negatively charged kaon condensation, an exotic phase that softens the equation of state and facilitate the reproduction of the inferred bulk properties of HESS J1731--347. We find that the onset of kaon condensation strongly accelerates the thermal evolution, leading to surface temperature substantially below the observationally inferred range. Within the adopted cooling framework, kaon condensation therefore cannot simultaneously account for the structural and thermal properties of HESS J1731--347.

Figures

Figures reproduced from arXiv: 2607.28107 by Ch.C. Moustakidis, D.G. Nanopoulos, M. Veselsky, P.S. Koliogiannis, V. Petousis.

Figure 1
Figure 1. Figure 1: FIG. 1. Mass–radius relations for the EoSs considered in this work. [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Radial profiles of the critical temperature for the neutron [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Radial profiles of the critical temperature for the nucleon pairing models listed in Table 1 of Ref. [ [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Evolution of the redshifted surface temperature with stellar age for (a) the purely hadronic MDI+APR1 configuration and (b) the [PITH_FULL_IMAGE:figures/full_fig_p006_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6. Evolution of the redshifted surface temperature with stellar [PITH_FULL_IMAGE:figures/full_fig_p007_6.png] view at source ↗

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

84 extracted references · 3 linked inside Pith

  1. [1]

    Flowers and N

    E. Flowers and N. Itoh, Transport properties of dense matter. III - Analytic formulae for thermal conductivity, Astrophys. J.250, 750 (1981)

    1981

  2. [2]

    D. A. Baiko and P. Haensel, Transport properties and neutrino emissivity of dense neutron star matter with localized protons, Acta Phys. Polon. B30, 1097 (1999)

    1999

  3. [3]

    Tamagaki, Superfluid State in Neutron Star Matter

    R. Tamagaki, Superfluid State in Neutron Star Matter. I: Gener- alized Bogoliubov Transformation and Existence of 3P2 Gap at High Density, Prog. Theor. Phys.44, 905 (1970)

    1970

  4. [4]

    Alford, Color-superconducting quark matter, Annu

    M. Alford, Color-superconducting quark matter, Annu. Rev. Nucl. Part. Sci.51, 131 (2001)

    2001

  5. [5]

    Alford, K

    M. Alford, K. Rajagopal, S. Reddy, and F. Wilczek, Minimal color-flavor-locked–nuclear interface, Phys. Rev. D64, 074017 (2001)

    2001

  6. [6]

    M. G. Alford, A. Schmitt, K. Rajagopal, and T. Sch¨afer, Color superconductivity in dense quark matter, Rev. Mod. Phys.80, 1455 (2008)

    2008

  7. [7]

    Klochkov, V

    D. Klochkov, V . Suleimanov, G. P¨uhlhofer, D. G. Yakovlev, A. Santangelo, and K. Werner, The neutron star in HESS J1731- 347: Central compact objects as laboratories to study the equa- tion of state of superdense matter, Astron. Astrophys.573, A53 (2015)

    2015

  8. [8]

    Doroshenko, V

    V . Doroshenko, V . Suleimanov, G. P¨uhlhofer, and A. Santangelo, A strangely light neutron star within a supernova remnant., Nat. Astron.6, 1444–1451 (2022)

    2022

  9. [9]

    C. M. Zhang, J. Wang, Y . H. Zhao, H. X. Yin, L. M. Song, D. P. Menezes, D. T. Wickramasinghe, L. Ferrario, and P. Chardonnet, Study of measured pulsar masses and their possible conclusions, Astron. Astrophys.527, A83 (2011)

    2011

  10. [10]

    S. R. Zhang, J. A. Rueda Hernandez, and R. Negreiros, Can the Central Compact Object in HESS J1731-347 Be Indeed the Lightest Neutron Star Observed?, Astrophys. J.978, 1 (2024)

    2024

  11. [11]

    Brodie and A

    L. Brodie and A. Haber, Nuclear and hybrid equations of state in light of the low-mass compact star in HESS J1731-347, Phys. Rev. C108, 025806 (2023)

    2023

  12. [12]

    Huang, H

    K. Huang, H. Shen, J. Hu, and Y . Zhang, Hadronic equation of state of low-mass neutron stars from a relativistic mean-field model with tensor couplings, Phys. Rev. D109, 043036 (2024)

    2024

  13. [13]

    J. J. Li and A. Sedrakian, Baryonic models of ultra-low-mass compact stars for the central compact object in HESS J1731-347, Phys. Lett. B844, 138062 (2023)

    2023

  14. [14]

    Kubis, W

    S. Kubis, W. W´ojcik, D. A. Castillo, and N. Zabari, Relativistic mean-field model for the ultracompact low-mass neutron star HESS J1731-347, Phys. Rev. C108, 045803 (2023)

    2023

  15. [15]

    Char and B

    P. Char and B. Biswas, Compact object of hess J1731-347 and its implication on neutron star matter, Phys. Rev. D113, 044002 (2026)

    2026

  16. [16]

    Tewari, S

    S. Tewari, S. Chatterjee, D. Kumar, and R. Mallick, Analyzing the dense matter equation of states in the light of the compact object HESS J1731-347, Phys. Rev. D111, 103009 (2025)

    2025

  17. [17]

    Tsaloukidis, P

    L. Tsaloukidis, P. S. Koliogiannis, A. Kanakis-Pegios, and C. C. Moustakidis, Twin stars as probes of the nuclear equation of state: Effects of rotation through the PSR J0952-0607 pulsar and constraints via the tidal deformability from the GW170817 event, Phys. Rev. D107, 023012 (2023)

    2023

  18. [18]

    Sagun, E

    V . Sagun, E. Giangrandi, T. Dietrich, O. Ivanytskyi, R. Negreiros, and C. Providˆencia, What Is the Nature of the HESS J1731-347 Compact Object?, Astrophys. J.958, 49 (2023)

    2023

  19. [19]

    Laskos-Patkos, P

    P. Laskos-Patkos, P. S. Koliogiannis, and C. C. Moustakidis, Hybrid stars in light of the HESS J1731-347 remnant and the PREX-II experiment, Phys. Rev. D109, 063017 (2024)

    2024

  20. [20]

    Laskos-Patkos, G

    P. Laskos-Patkos, G. A. Lalazissis, S. Wang, J. Meng, P. Ring, and C. C. Moustakidis, Speed of sound bounds and first-order phase transitions in compact stars, Phys. Rev. C111, 025801 (2025)

    2025

  21. [21]

    J. J. Li, A. Sedrakian, and M. Alford, Hybrid Star Models in the Light of New Multimessenger Data, Astrophys. J.967, 116 (2024)

    2024

  22. [22]

    Mariani, I

    M. Mariani, I. F. Ranea-Sandoval, G. Lugones, and M. G. Or- saria, Could a slow stable hybrid star explain the central compact object in HESS J1731-347?, Phys. Rev. D110, 043026 (2024)

    2024

  23. [23]

    Gholami, I

    H. Gholami, I. A. Rather, M. Hofmann, M. Buballa, and J. Schaffner-Bielich, Astrophysical constraints on color- superconducting phases in compact stars within the RG- consistent NJL model, Phys. Rev. D111, 103034 (2025)

    2025

  24. [24]

    B. Gao, Y . Yan, and M. Harada, Reconciling constraints from the supernova remnant HESS J1731-347 with the parity doublet model, Phys. Rev. C109, 065807 (2024)

    2024

  25. [25]

    S. Pal, S. Podder, and G. Chaudhuri, Is the Central Compact Object in HESS J1731-347 a Hybrid Star with a Quark Core? An Analysis with the Constant Speed of Sound Parameterization, Astrophys. J.983, 24 (2025)

    2025

  26. [26]

    D. E. Alvarez-Castillo, Properties of the Object HESS J1731-347 as a Twin Compact Star, Universe11, 224 (2025)

    2025

  27. [27]

    Kubis and W

    S. Kubis and W. W´ojcik, Does HESS J1731-347 have a thick crust ? (2025), arXiv:2507.06837 [nucl-th]

    Pith/arXiv arXiv 2025

  28. [28]

    Di Clemente, A

    F. Di Clemente, A. Drago, and G. Pagliara, Is the Compact Ob- ject Associated with HESS J1731-347 a Strange Quark Star? A Possible Astrophysical Scenario for Its Formation, Astrophys. J. 967, 159 (2024)

    2024

  29. [29]

    J. E. Horvath, L. S. Rocha, L. M. de S´a, P. H. R. S. Moraes, L. G. Bar˜ao, M. G. B. de Avellar, A. Bernardo, and R. R. A. Bachega, A light strange star in the remnant HESS J1731–347: Minimal consistency checks, Astron. Astrophys.672, L11 (2023)

    2023

  30. [30]

    P. T. Oikonomou and C. C. Moustakidis, Color-flavor locked quark stars in light of the compact object in the HESS J1731-347 and the GW190814 event, Phys. Rev. D108, 063010 (2023)

    2023

  31. [31]

    H. C. Das and L. L. Lopes, Anisotropic strange stars in the spotlight: unveiling constraints through observational data, Mon. Not. Roy. Astron. Soc.525, 3571 (2023)

    2023

  32. [32]

    I. A. Rather, G. Panotopoulos, and I. Lopes, Quark models and radial oscillations: decoding the HESS J1731-347 compact ob- ject’s equation of state, Eur. Phys. J. C83, 1065 (2023)

    2023

  33. [33]

    Kourmpetis, P

    K. Kourmpetis, P. Laskos-Patkos, and C. C. Moustakidis, Con- fronting recent light compact star observations with color-flavor locked quark matter, Front. Astron. Space Sci.12, 1600563 (2025)

    2025

  34. [34]

    Yang and C.-M

    S.-H. Yang and C.-M. Pi, Color-flavor locked strange stars ad- mixed with mirror dark matter and the observations of compact stars, J. Cosmol. Astropart. Phys.2024(09), 052

    2024

  35. [35]

    Veselsk´y, P

    M. Veselsk´y, P. Koliogiannis, V . Petousis, J. Leja, and C. Mous- takidis, How the HESS J1731-347 object could be explained usingK − condensation, Phys. Lett. B860, 139185 (2025)

    2025

  36. [36]

    Veselsk´y, V

    M. Veselsk´y, V . Petousis, P. S. Koliogiannis, C. C. Moustakidis, and J. Leja, Simultaneous explanation of XTE J1814-338 and HESS J1731-347 objects using K − and K 0 condensates, Phys. Rev. D111, L061308 (2025)

    2025

  37. [37]

    Acero, M

    F. Acero, M. Lemoine-Goumard, M. Renaud, J. Ballet, J. W. He- witt, R. Rousseau, and T. Tanaka, Study of TeV shell supernova remnants at gamma-ray energies, Astron. Astrophys.580, A74 (2015). 9

    2015

  38. [38]

    Y . Cui, G. P¨uhlhofer, and A. Santangelo, A young supernova remnant illuminating nearby molecular clouds with cosmic rays, Astron. Astrophys.591, A68 (2016)

    2016

  39. [39]

    Maxted, M

    N. Maxted, M. Burton, C. Braiding, G. Rowell, H. Sano, F. V oisin, M. Capasso, G. P¨uhlhofer, and Y . Fukui, Probing the local environment of the supernova remnant HESS J1731-347 with CO and CS observations, Mon. Not. Roy. Astron. Soc.474, 662 (2018)

    2018

  40. [40]

    Yuan and X

    Y .-J. Yuan and X. Zhou, Thermal Evolution of the Central Com- pact Object in HESS J1731-347 as Evidence for a Color-flavor- locked Strange Star, Res. Astron. Astrophys.25, 055016 (2025)

    2025

  41. [41]

    D. G. Nanopoulos, P. Laskos-Patkos, and C. C. Moustakidis, On the Cooling of Compact Stars in Light of the HESS J1731-347 Remnant, Universe12, 18 (2026)

    2026

  42. [42]

    Thorsson, M

    V . Thorsson, M. Prakash, and J. M. Lattimer, Composition, struc- ture and evolution of neutron stars with kaon condensates, Nuc. Phys. A572, 693 (1994)

    1994

  43. [43]

    Y . Lim, K. Kwak, C. H. Hyun, and C.-H. Lee, Kaon condensation in neutron stars with Skyrme-Hartree-Fock models, Phys. Rev. C89, 055804 (2014)

    2014

  44. [44]

    P. S. Koliogiannis and C. C. Moustakidis, Thermodynamical De- scription of Hot, Rapidly Rotating Neutron Stars, Protoneutron Stars, and Neutron Star Merger Remnants, Astrophys. J.912, 69 (2021)

    2021

  45. [45]

    D. G. Yakovlev, K. P. Levenfish, and Y . A. Shibanov, Cooling of neutron stars and superfluidity in their cores, Phys. Usp.42, 737 (1999)

    1999

  46. [46]

    Yakovlev, A

    D. Yakovlev, A. Kaminker, O. Gnedin, and P. Haensel, Neutrino emission from neutron stars, Phys. Rep.354, 1 (2001)

    2001

  47. [47]

    Thorsson, M

    V . Thorsson, M. Prakash, T. Tatsumi, and C. J. Pethick, Neutrino emission from dense matter containing meson condensates, Phys. Rev. D52, 3739–3741 (1995)

    1995

  48. [48]

    D. D. Ofengeim, M. Fortin, P. Haensel, D. G. Yakovlev, and J. L. Zdunik, Neutrino luminosities and heat capacities of neutron stars in analytic form, Phys. Rev. D96, 043002 (2017)

    2017

  49. [49]

    B. L. Friman and O. V . Maxwell, Neutrino emissivities of neu- tron stars., Astrophys. J.232, 541 (1979)

    1979

  50. [50]

    D. G. Yakovlev and K. P. Levenfish, Modified URCA process in neutron star cores., Astron. Astrophys.297, 717 (1995)

    1995

  51. [51]

    Kubis and M

    S. Kubis and M. Kutschera, Kaon condensates, nuclear symmetry energy and cooling of neutron stars, Nucl. Phys. A720, 189 (2003)

    2003

  52. [52]

    Kubis, Neutrino emissivity under neutral kaon condensation, Phys

    S. Kubis, Neutrino emissivity under neutral kaon condensation, Phys. Rev. C73, 015805 (2006)

    2006

  53. [53]

    Grigorian and D

    H. Grigorian and D. N. V oskresensky, Medium effects in cooling of neutron stars and the 3P2 neutron gap, Astron. Astrophys.444, 913 (2005)

    2005

  54. [54]

    B. Bhat, A. Dohi, T. Muto, and T. Noda, Cooling of Isolated Neutron Stars with Hyperon-mixed Kaon-Condensation Matter (2026), arXiv:2605.09723 [astro-ph.HE]

    Pith/arXiv arXiv 2026

  55. [55]

    Yakovlev, O

    D. Yakovlev, O. Gnedin, A. Kaminker, K. Levenfish, and A. Potekhin, Neutron star cooling: theoretical aspects and obser- vational constraints, Adv. Space Res.33, 523 (2004)

    2004

  56. [56]

    Baldo, J

    M. Baldo, J. Cugnon, A. Lejeune, and U. Lombardo, Superflu- idity in neutron matter and nuclear matter with realistic interac- tions, Nucl. Phys. A515, 409 (1990)

    1990

  57. [57]

    Baldo, J

    M. Baldo, J. Cugnon, A. Lejeune, and U. Lombardo, Proton and neutron superfluidity in neutron star matter, Nucl. Phys. A536, 349 (1992)

    1992

  58. [58]

    J. M. C. Chen, J. W. Clark, R. D. Dav´e, and V . V . Khodel, Pairing gaps in nucleonic superfluids, Nucl. Phys. A555, 59 (1993)

    1993

  59. [59]

    Takatsuka and R

    T. Takatsuka and R. Tamagaki, Superfluidity in neutron star matter and symmetric nuclear matter, Prog. Theor. Phys. Suppl. 112, 27 (1993)

    1993

  60. [60]

    Elgarøy, L

    O. Elgarøy, L. Engvik, M. Hjorth-Jensen, and E. Osnes, Super- fluidity in β-Stable Neutron Star Matter, Phys. Rev. Lett.77, 1428 (1996)

    1996

  61. [61]

    Amundsen and E

    L. Amundsen and E. Østgaard, Superfluidity of neutron matter: (I). Singlet pairing, Nucl. Phys. A437, 487 (1985)

    1985

  62. [62]

    Schaab, F

    C. Schaab, F. Weber, M. K. Weigel, and N. K. Glendenning, Thermal evolution of compact stars, Nucl. Phys. A605, 531 (1996)

    1996

  63. [63]

    A. D. Kaminker, D. G. Yakovlev, and O. Y . Gnedin, Three types of cooling superfluid neutron stars: Theory and observations, Astron. Astrophys.383, 1076 (2002)

    2002

  64. [64]

    Andersson, G

    N. Andersson, G. Comer, and K. Glampedakis, How viscous is a superfluid neutron star core?, Nucl. Phys. A763, 212 (2005)

    2005

  65. [65]

    W. C. G. Ho, K. G. Elshamouty, C. O. Heinke, and A. Y . Potekhin, Tests of the nuclear equation of state and superfluid and superconducting gaps using the Cassiopeia A neutron star, Phys. Rev. C91, 015806 (2015)

    2015

  66. [66]

    A. D. Kaminker, P. Haensel, and D. G. Yakovlev, Nucleon su- perfluidity vs. observations of cooling neutron stars, Astron. Astrophys.373, L17 (2001)

    2001

  67. [67]

    Blaschke, H

    D. Blaschke, H. Grigorian, and D. N. V oskresensky, Cooling of neutron stars. Hadronic model, Astron. Astrophys.424, 979 (2004)

    2004

  68. [68]

    D. N. V oskresensky and A. V . Senatorov, Description of Nuclear Interaction in Keldysh’s Diagram Technique and Neutrino Lu- minosity of Neutron Stars. (In Russian), Sov. J. Nucl. Phys.45, 411 (1987)

    1987

  69. [69]

    Blaschke, H

    D. Blaschke, H. Grigorian, and D. N. V oskresensky, Cooling of hybrid neutron stars and hypothetical self-bound objects with su- perconducting quark cores, Astron. Astrophys.368, 561 (2001)

    2001

  70. [70]

    O. V . Maxwell, Neutron star cooling., Astrophys. J.231, 201 (1979)

    1979

  71. [71]

    E. H. Gudmundsson, C. J. Pethick, and R. I. Epstein, Structure of neutron star envelopes, Astrophys. J.272, 286 (1983)

    1983

  72. [72]

    Cumming, E

    A. Cumming, E. F. Brown, F. J. Fattoyev, C. J. Horowitz, D. Page, and S. Reddy, Lower limit on the heat capacity of the neutron star core, Phys. Rev. C95, 025806 (2017)

    2017

  73. [73]

    K. S. Thorne, The relativistic equations of stellar structure and evolution., Astrophys. J.212, 825 (1977)

    1977

  74. [74]

    D. G. Yakovlev, W. C. G. Ho, P. S. Shternin, C. O. Heinke, and A. Y . Potekhin, Cooling rates of neutron stars and the young neutron star in the Cassiopeia A supernova remnant, Mon. Not. Roy. Astron. Soc.411, 1977 (2011)

    1977

  75. [75]

    D. Page, U. Geppert, and F. Weber, The cooling of compact stars, Nucl. Phys. A777, 497 (2006)

    2006

  76. [76]

    Glen and P

    G. Glen and P. Sutherland, On the cooling of neutron stars, Astrophys. J.239, 671 (1980)

    1980

  77. [77]

    Salmi, D

    T. Salmi, D. Choudhury, Y . Kini,et al., The Radius of the High- mass Pulsar PSR J0740+6620 with 3.6 yr of NICER Data, As- trophys. J.974, 294 (2024)

    2024

  78. [78]

    Choudhury, T

    D. Choudhury, T. Salmi, S. Vinciguerra,et al., A NICER View of the Nearest and Brightest Millisecond Pulsar: PSR J0437–4715, Astrophys. J. Lett.971, L20 (2024)

    2024

  79. [79]

    M. C. Miller, F. K. Lamb, A. J. Dittmann,et al., PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter, Astrophys. J. Lett.887, L24 (2019)

    2019

  80. [80]

    B. P. Abbott, R. Abbott, T. D. Abbott,et al.(The LIGO Scientific Collaboration and the Virgo Collaboration), GW170817: Mea- surements of Neutron Star Radii and Equation of State, Phys. Rev. Lett.121, 161101 (2018)

    2018

Showing first 80 references.

This paper was first reviewed by grok-4.5 on July 31, 2026.