J/A+A/640/A77     Crystallization of a neutron star inner crust (Carreau+, 2020)

Inner crust of a neutron star at the point of crystallization in a multi-component approach. Carreau T., Fantina A.F., Gulminelli F. <Astron. Astrophys. 640, A77 (2020)> =2020A&A...640A..77C 2020A&A...640A..77C (SIMBAD/NED BibCode)
ADC_Keywords: Pulsars ; Atomic physics Keywords: stars: neutron - dense matter - plasmas Abstract: The possible presence of amorphous and heterogeneous phases in the inner crust of a neutron star is expected to reduce the electrical conductivity of the crust, with potentially important consequences on the magneto-thermal evolution of the star. In cooling simulations, the disorder is quantified by an impurity parameter which is often taken as a free parameter. We aim to give a quantitative prediction of the impurity parameter as a function of the density in the crust, performing microscopic calculations including up-to-date microphysics of the crust. A multi-component approach is developed at finite temperature using a compressible liquid drop description of the ions with an improved energy functional based on recent microscopic nuclear models and optimized on extended Thomas-Fermi calculations. Thermodynamic consistency is ensured by adding a rearrangement term and deviations from the linear mixing rule are included in the liquid phase. The impurity parameter is consistently calculated at the crystallization temperature as determined in the one-component plasma approximation for the different functionals. Our calculations show that at the crystallization temperature the composition of the inner crust is dominated by nuclei with charge number around Z∼40, while the range of the Z distribution varies from about 20 near the neutron drip to about 40 closer to the crust-core transition. This reflects on the behavior of the impurity parameter that monotonically increases with density up to around 40 in the deeper regions of the inner crust. Our study shows that the contribution of impurities is non-negligible, thus potentially having an impact on the transport properties in the neutron-star crust. The obtained values of the impurity parameter represent a lower limit; larger values are expected in the presence of non-spherical geometries and/or fast cooling dynamics. Description: The impurity parameter obtained in a self-consistent multi-component plasma approach at equilibrium is presented. For each value of baryon mass density in the range relevant for the inner crust of a non-accreting neutron star, the value of the impurity parameter at the crystallization temperature and at T=1010K is given. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file tm_bsk22.dat 49 52 Baryon density, pressure, melting temperature, and impurity parameter using BSk22 tm_bsk24.dat 49 52 Baryon density, pressure, melting temperature, and impurity parameter using BSk24 tm_bsk25.dat 49 52 Baryon density, pressure, melting temperature, and impurity parameter using BSk25 tm_bsk26.dat 49 52 Baryon density, pressure, melting temperature, and impurity parameter using BSk26 t10bsk22.dat 49 52 Baryon density, pressure, temperature, and impurity parameter using BSk22 t10bsk24.dat 49 52 Baryon density, pressure, temperature, and impurity parameter using BSk24 t10bsk25.dat 49 51 Baryon density, pressure, temperature, and impurity parameter using BSk25 t10bsk26.dat 49 52 Baryon density, pressure, temperature, and impurity parameter using BSk26 -------------------------------------------------------------------------------- See also: J/A+A/633/A149 : Crystallization of neutron star outer crust (Fantina+, 2020) Byte-by-byte Description of file: *.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 E10.4 cm-3 nb Baryon density 14- 23 E10.4 dPa P Pressure (1) 27- 36 E10.4 K Tm Crystallization temperature 40- 49 E10.4 --- Qimp Impurity parameter at Tm (2) -------------------------------------------------------------------------------- Note (1): The SI unit dPa is equivalent to the CGS unit erg/cm3 or equivalent to dyn/cm2. The conversion factor between the nuclear units for the pressure (MeV/fm3) and the SI unit dPa is 1.6021766e33. Note (2): The impurity parameter is dimensionless. -------------------------------------------------------------------------------- Acknowledgements: Thomas Carreau, carreau(at)lpccaen.in2p3.fr References: Fantina, De Ridder, Chamel & Gulminelli, 2020A&A...633A.149F 2020A&A...633A.149F, Cat. J/A+A/633/A149 Carreau, Gulminelli, Chamel, Fantina & Pearson, 2020A&A...635A..84C 2020A&A...635A..84C
(End) Thomas Carreau [LPC, Caen], Patricia Vannier [CDS] 08-Jul-2020
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