nEoS

neutron matter Equation of State

You can find Equations of State for neutron stars constrained by basic principles and generated with Hadron Physics input alone
(low-density: Chiral Perturbation Theory for neutron matter; high-density pQCD; intermediate density: monotonicity and causality).
In particular, no Astrophysics nor General Relativity input has been used. Thus, our sets are less constrained than others, but also less biased:
you may want to use them, for example, if you are thinking of testing General Relativity or modified theories of gravity with neutron stars.
Random sampling of allowed band in the energy density/pressure diagram. Agnostic about exotic phases in the QCD diagram. Phase transitions are in principle allowed.
Citation: Eva Lope Oter, Andreas Windisch, Felipe J. Llanes-Estrada and Mark Alford, J.Phys.G 46 (2019) 8, 084001, arXiv:1901.05271
All sets contain files with two columns of floating-point numbers (ε,P) in MeV/fm³
Given for two baryon chemical potentials at which pQCD is matched to the intermediate density region.
These are all at zero temperature; some EoS for T=10, 20 and 30 MeV are separately provided under nEoS-T in this same server

Quick start: a few sample typical EoS that satisfy all basic constraints.
(Ideal for your class or to toy with a new idea.)

Input constraints from low-density (ChPT).

Full sets
(about 0.5 MByte each)

Set 1: low-density constrained by Sammarruca et al. @NLO:

Matching baryon chemical potential 2.6 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Matching baryon chemical potential 2.8 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Sammarruca et al., NLO

Momentum cutoff
Λ=450 MeV

Λ=600 MeV

Tables provided as a .tar.gz file contain 1000 EoS

1a) Matching baryon chemical potential 2.6 GeV

EOS_Sammarruca_NLO

1b) Matching baryon chemical potential 2.8 GeV

EOS_Sammarruca_NLO

Set 2: low-density constrained by Sammarruca et al. @(partly) NNLO:
Matching baryon chemical potential 2.6 GeV.

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Matching baryon chemical potential 2.8 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Sammarruca et al.,
(partly) N²LO

Λ= 450 MeV

Λ= 600 MeV

Tables provided as a .tar.gz file contain 1000 EoS

2a) Matching baryon chemical potential 2.6 GeV

EOS_Sammarruca_N2LO

2b) Matching baryon chemical potential 2.8 GeV

EOS_Sammarruca_N2LO

Set 3: low-density constrained by Sammarruca et al. @(partly) N3LO

Matching baryon chemical potential 2.6 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Matching baryon chemical potential 2.8 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Sammarruca et al.,
(partly) N³LO

Λ= 450 MeV

Λ= 600 MeV

Tables provided as a .tar.gz file contain 1000 EoS

3a) Matching baryon chemical potential 2.6 GeV

EOS_Sammarruca_N3LO

3b) Matching baryon chemical potential 2.8 GeV

EOS_Sammarruca_N3LO

Set 4: low-density constrained by Hu et al.@NLO

Matching baryon chemical potential 2.6 GeV.

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Matching baryon chemical potential 2.8 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Hu et al. NLO

Coordinate space cutoff
R = 0.9 fm

R = 1.0 fm

Tables provided as a .tar.gz file contain 1000 EoS

4a) Matching baryon chemical potential 2.6 GeV

EOS_Hu_NLO

4b) Matching baryon chemical potential 2.8 GeV

EOS_Hu_NLO

Set 5: low-density constrained by Hu et al.@(partly)N³LO

Matching baryon chemical potential 2.6 GeV.

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Matching baryon chemical potential 2.8 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Hu et al. (partly) N³LO

R = 0.9 fm

R = 1.0 fm

Tables provided as a .tar.gz file contain 1000 EoS

5a) Matching baryon chemical potential 2.6 GeV

EOS_Hu_N3LO

5b) Matching baryon chemical potential 2.8 GeV

EOS_Hu_N3LO

Set 6: low-density constrained by Hu et al.@N⁴LO

(not quite complete computation: to be used only to check convergence)

Matching baryon chemical potential 2.6 GeV.

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Matching baryon chemical potential 2.8 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Hu et al. (partly) N⁴LO

R = 0.9 fm

R = 1.0 fm

Tables provided as a .tar.gz file contain 1000 EoS

6a) Matching baryon chemical potential 2.6 GeV

EOS_Hu_N4LO

6b) Matching baryon chemical potential 2.8 GeV

EOS_Hu_N4LO

Set 7: low-density constrained by Drischler et al.;

Matching baryon chemical potential 2.6 GeV.

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5.

Matching baryon chemical potential 2.8 GeV.

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5.

Drischler et al.

Lower boundary of allowed band

Upper boundary of allowed band

Tables provided as a .tar.gz file contain 1000 EoS

7a) Matching baryon chemical potential 2.6 GeV

EOS_Drischler

7b) Matching baryon chemical potential 2.8 GeV

EOS_Drischler

Set 8: low-density constrained by Holt and Kaiser @ NLO

Matching baryon chemical potential 2.6 GeV.

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Matching baryon chemical potential 2.8 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Holt and Kaiser, NLO

Λ= 450 MeV

Λ= 500 MeV

Tables provided as a .tar.gz file contain 1000 EoS

8a) Matching baryon chemical potential 2.6 GeV

EOS_Holt_NLO

8b) Matching baryon chemical potential 2.8 GeV

EOS_Holt_NLO

Set 9: low-density constrained by Holt and Kaiser @(partly) N2LO

Matching baryon chemical potential 2.6 GeV.

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Matching baryon chemical potential 2.8 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Holt and Kaiser
(partly) N²LO

Λ= 450 MeV

Λ= 500 MeV

Tables provided as a .tar.gz file contain 1000 EoS

9a) Matching baryon chemical potential 2.6 GeV

EOS_Holt_N2LO

9b) Matching baryon chemical potential 2.8 GeV

EOS_Holt_N2LO

Set 10: low-density constrained by Holt and Kaiser @(partly) N3LO

Matching baryon chemical potential 2.6 GeV.

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Matching baryon chemical potential 2.8 GeV

Sample EoS 1; Sample EoS 2;
Sample EoS 3; Sample EoS 4;
Sample EoS 5

Holt and Kaiser
(partly) N³LO

Λ= 450 MeV

Λ= 500 MeV

Tables provided as a .tar.gz file contain 1000 EoS

10a) Matching baryon chemical potential 2.6 GeV

EOS_Holt_N3LO

10b) Matching baryon chemical potential 2.8 GeV

EOS_Holt_N3LO

Input band from high-density (pQCD, Kurkela et al.); μ as specified; three columns, (ε, Pmin, Pmax).

With matching baryon chemical potential 2.6 GeV

With matching baryon chemical potential 2.8 GeV

Fortran code to generate your own EoS set
Provided for free as is; no liability assumed under any circumstance.

You can use it under the full Creative Commons License

generate_EoS_down6.f90

generate_EoS_down6v2.f90

aux.f90

.tar.gz packs
Basic usage: Download and extract in a separate folder. Each inflates to 1000 two-column (energy density and pressure) floating point number files. Units are MeV over cubed Fermi.

References to QCD-based low and high density EoS computations used here (from InspireHEP)

Sammarruca et al. Hu et al. Drischler et al. Holt and Kaiser Kurkela et al. (pQCD)

We do not know of an investigation of the crustal (lowest-density) EoS whose systematic uncertainties are guaranteed so we have not incorporated it into our tables. But should it become strictly necessary to supplement them, a reasonable starting point would be the work of Sharma et al. published in Astron.Astrophys. 584 (2015) A103.

Acknowledgment of support

Work supported by grants MINECO:FPA2016-75654-C2-1-P (Spain) and by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Award Number #DE-FG02-05ER41375.

The Univ. Complutense team thanks the members of the EU COST Action PHAROS (CA16214) and the IPARCOS institute for a stimulating scientific environment
as well as David Fernandez Sanz for computer assistance.

Site maintained by
Felipe J. Llanes Estrada
and Eva Lope-Oter

Animation by Andreas Windisch
hosted at the Departamento de Física Teórica,
Univ. Complutense, Madrid