Description
The equations of state (EOSs) for neutron-star matter are fitted
from mass density rho about 105 g cm-3
to a few times 1015 g cm-3
(baryon number density n about 10-10 fm-3
- a few fm-3). At the low end of this density range,
the EOS starts to depend on temperature T.
The fits are extended below this density
by matching to the dependence P=3.5x1014rho,
where pressure P and rho are in CGS units;
this is an approximation for the EOS of iron at
T = 107 K and
rho = (0.1 - 1000) g cm-3.
Arguments of the program:
- MODE - an integer (1, 2, or 3) that
identifies which of the arguments is the input
(XN, RHO, or H1)
- KEOS - an integer (1, 2, or 3) that
identifies which EOS has to be used (SLy4, FPS, or SLy4+APR*)
- XN - number density n in fm-3
- RHO - mass density rho in g cm-3;
RLG=log10(RHO)
- H1 - h/h0-1,
where h is the enthalpy per baryon,
and h0=m0c2
is its value near the surface
- P - pressure P in dyn cm-2;
PLG=log10(P)
- Gamma - adiabatic index, (d log P) / (d log n)
(for more explanations and definitions see
the references).
The subroutine NSEOSFIT(MODE,KEOS,XN,RHO,H1,P,Gamma) returns
4 fitted arguments for 1 input (XN, RHO, or H1). It uses
subroutines that realize separate fits: P(rho),
n(rho), rho(n), rho(H1).
Typical accuracy of the fits is a few percent or better.
To achieve the perfect thermodynamic consistency,
however, it is advised not to use all the
fitted outputs, but to calculate either XN(RHO,P) or RHO(XN,P)
using the thermodynamic identities given, e.g.,
by Eqs.(2),(3) of the
basic reference
paper
(Haensel and Potekhin 2004).
Please communicate us your opinion about this resource or send
any suggestions or remarks.
Tabular EOSs:
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Code to download:
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