NUCLEAR CONSTRAINTS ON PROPERTIES OF NEUTRON STAR CRUSTS

The transition density {rho} {sub t} and pressure P{sub t} at the inner edge separating the liquid core from the solid crust of neutron stars are systematically studied using a modified Gogny (MDI) and 51 popular Skyrme interactions within well established dynamical and thermodynamical methods. Firs...

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Bibliographic Details
Published in:The Astrophysical journal 2009-06, Vol.697 (2)
Main Authors: Xu Jun, Chen Liewen, Ma Hongru, Li Baoan
Format: Article
Language:English
Subjects:
APPROXIMATIONS
ASYMMETRY
DENSITY
EQUATIONS OF STATE
FUNCTIONALS
HEAVY ION REACTIONS
ISOSPIN
MASS
MOMENT OF INERTIA
NEUTRON STARS
NEUTRONS
NUCLEAR MATTER
NUCLEAR PHYSICS AND RADIATION PHYSICS
PULSARS
SKYRME POTENTIAL
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Summary:The transition density {rho} {sub t} and pressure P{sub t} at the inner edge separating the liquid core from the solid crust of neutron stars are systematically studied using a modified Gogny (MDI) and 51 popular Skyrme interactions within well established dynamical and thermodynamical methods. First of all, it is shown that the widely used parabolic approximation to the full equation of state (EOS) of isospin asymmetric nuclear matter may lead to huge errors in estimating the transition density and pressure, especially for stiffer symmetry energy functionals E {sub sym}({rho}), compared to calculations using the full EOS within both the dynamical and thermodynamical methods mainly because of the energy curvatures involved. Thus, fine details of the EOS of asymmetric nuclear matter are important for locating accurately the inner edge of the neutron star crust. Second, the transition density and pressure decrease roughly linearly with increasing slope parameter L of E {sub sym}({rho}) at normal nuclear matter density using the full EOS within both the dynamical and thermodynamical methods. It is also shown that the thickness, fractional mass, and moment of inertia of the neutron star crust are all very sensitive to the parameter L through the transition density {rho} {sub t} whether one uses the full EOS or its parabolic approximation. Moreover, it is shown that E {sub sym}({rho}) constrained in the same subsaturation density range as the neutron star crust by the isospin diffusion data in heavy-ion collisions at intermediate energies limits the transition density and pressure to 0.040 fm{sup -3} {
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/697/2/1549;COUNTRYOFINPUT:INTERNATIONALATOMICENERGYAGENCY(IAEA)