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