Universal symmetry energy contribution to the neutron star equation of state

D. Blaschke; D. E. Alvarez-Castillo; T. Klahn

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Universal symmetry energy contribution to the neutron star equation of state

D. Blaschke, D. E. Alvarez-Castillo, T. Klahn

Nuclear Theory · Submitted 28 Apr 2016

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim We discuss the observation that under neutron star conditions of charge neutrality and $\beta-$equilibrium the contribution from the symmetry energy to the equation of state (EoS) follows a universal behaviour.

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arXiv ID1604.08575 (version 2)

Pith IDMWR34MDB, Pith's permanent record of this paper and its review

CitationD. Blaschke, D. E. Alvarez-Castillo, T. Klahn. "Universal symmetry energy contribution to the neutron star equation of state." arXiv:1604.08575 (2016). https://pith.science/paper/MWR34MDB

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Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 4,979 input tokens.

What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.72 · human participants 0.01 · controlled comparison 0.03 · randomized assignment 0.01 · states quantitative result 0.13 · compares with prior results 0.14 · mentions code or data availability 0.02.

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We discuss the observation that under neutron star conditions of charge neutrality and $\beta-$equilibrium the contribution from the symmetry energy to the equation of state (EoS) follows a universal behaviour. We call this behaviour the conjecture of a Universal Symmetry Energy Contribution (USEC). We find that an USEC holds provided the density dependence of the symmetry energy $E_s(n)$ follows a behaviour that limits the proton fraction $x(n)$ to values below the threshold for the direct Urca (DU) cooling process. The absence of DU cooling in typical mass neutron stars appears to be supported by the phenomenology of neutron star cooling data and allows to constrain the behaviour of $E_s(n)$ at high densities. Two classes of symmetry energy functions are investigated more in detail to elucidate the USEC. We derive an analytic formula for the USEC to the neutron star EoS based on the result for the symmetry energy extracted from isobaric analog states of nuclei.

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What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	We discuss the observation that under neutron star conditions of charge neutrality and $\beta-$equilibrium the contribution from the symmetry energy to the equation of state (EoS) follows a universal behaviour.	result 0.76	0.20	0.64	asserted 0.83
s1	We call this behaviour the conjecture of a Universal Symmetry Energy Contribution (USEC).	contribution 0.55	0.71	0.13	asserted 0.67
s2	We find that an USEC holds provided the density dependence of the symmetry energy $E_s(n)$ follows a behaviour that limits the proton fraction $x(n)$ to values below the threshold for the direct Urca (DU) cooling process.	result 0.97	0.90	0.47	asserted 0.99
s3	The absence of DU cooling in typical mass neutron stars appears to be supported by the phenomenology of neutron star cooling data and allows to constrain the behaviour of $E_s(n)$ at high densities.	interpretation 0.81	0.26	0.18	hedged possibility 0.91
s4	Two classes of symmetry energy functions are investigated more in detail to elucidate the USEC.	method 0.66	0.79	0.03	asserted 0.86
s5	We derive an analytic formula for the USEC to the neutron star EoS based on the result for the symmetry energy extracted from isobaric analog states of nuclei.	result 0.59	0.95	0.14	asserted 1.00

What kind of paper the classifier reports this is: theoretical result 1.00 · evidence from proof or derivation 0.85.

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The paper

Original abstract

We discuss the observation that under neutron star conditions of charge neutrality and $\beta-$equilibrium the contribution from the symmetry energy to the equation of state (EoS) follows a universal behaviour. We call this behaviour the conjecture of a Universal Symmetry Energy Contribution (USEC). We find that an USEC holds provided the density dependence of the symmetry energy $E_s(n)$ follows a behaviour that limits the proton fraction $x(n)$ to values below the threshold for the direct Urca (DU) cooling process. The absence of DU cooling in typical mass neutron stars appears to be supported by the phenomenology of neutron star cooling data and allows to constrain the behaviour of $E_s(n)$ at high densities. Two classes of symmetry energy functions are investigated more in detail to elucidate the USEC. We derive an analytic formula for the USEC to the neutron star EoS based on the result for the symmetry energy extracted from isobaric analog states of nuclei.

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References

Forward citations

Cited by 2 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. OpenAlex reports about 7 citations worldwide. Full citation record

The Radius of the Neutron Star PSR J0614-3329 from NICER Data
astro-ph.HE 2026-09 conditional novelty 6.0 of 10

Modeling NICER pulses from PSR J0614-3329 gives an equatorial radius of 9.88 to 12.77 km at 68% credibility, consistent with but centered lower than other 1.4 solar-mass neutron stars.
The Radius of PSR J0437-4715 from NICER Data
astro-ph.HE 2025-12 conditional novelty 5.0 of 10

Modeling NICER data with an added modulated nonthermal component yields a PSR J0437−4715 radius of 11.8–15.1 km and shows that omitting this component biases radius estimates.

How the literature uses it

12 arXiv papers cite this in 17 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 9 sentences without a confident label

Builds on it 1 paper

Our analysis confirms the universal behavior of the EOS discussed in Ref. [ref] and generalizes it to cases where dUrca is allowed for large masses.

The equation of state for dense nucleonic matter from a meta-modeling. II. Predictions for neutron stars properties · Impact on the equation of state at $β$-equilibrium · 0.98

Uses its method or tool 1 paper

Here we compute $S$ at saturation density by imposing beta equilibrium on the matter, including the possible presence of muons, using the formulae in Section II of [ref] .

The Radius of PSR J0437-4715 from NICER Data · Statistical Method · 0.99

Cites it as support 2 papers

It explains why the global properties of the NS shown in Figs. [ref] and [ref] are not very much impacted by these hypothesis, and reflects the universality of the EOS under the charge neutrality and $β$-equilibrium conditions [ref] .

The equation of state for dense nucleonic matter from a meta-modeling. II. Predictions for neutron stars properties · Impact on the equation of state at $β$-equilibrium · 0.97
We do not expect however that this alters significantly the present comparison because of the compensating mechanism discussed in Refs. [ref] : the increase of the pressure due to the electrons balances the decrease of the symmetry energy due to the proton excess (at fixed total baryon density).

Thermodynamics of the parity-doublet model: Asymmetric and neutron matter · Constraints from neutron stars · 0.96

Cites it as background 3 papers

During the last two decades, significant efforts have been devoted to exploring the using both terrestrial laboratory experiments [ref] and astrophysical observations [ref] .

How tightly is nuclear symmetry energy constrained by unitary Fermi gas? · Introduction · 0.98
Comprehensive reviews on the recent progress and remaining challenges in constraining the can be found in the literature [ref] .

Nuclear Symmetry Energy Extracted from Laboratory Experiments · Introduction · 0.94
[ref] for reviews.

Towards Understanding Astrophysical Effects of Nuclear Symmetry Energy · What have we learned about the symmetry energy so far? · 0.89

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