scholarly journals Effects of dark matter on the nuclear and neutron star matter

2020 ◽  
Vol 495 (4) ◽  
pp. 4893-4903 ◽  
Author(s):  
H C Das ◽  
Ankit Kumar ◽  
Bharat Kumar ◽  
S K Biswal ◽  
Takashi Nakatsukasa ◽  
...  
Keyword(s):  
Dark Matter ◽  
Neutron Star ◽  
Symmetry Energy ◽  
Mean Field ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
Equation Of States ◽  
Astrophysical Objects ◽  
Pure Neutron Matter ◽  
The Moment

ABSTRACT We study the dark matter (DM) effects on the nuclear matter (NM) parameters characterizing the equation of states of super dense neutron-rich nucleonic matter. The observables of the NM, i.e. incompressibility, symmetry energy and its higher order derivatives in the presence DM for symmetric and asymmetric NM are analysed with the help of an extended relativistic mean field model. The calculations are also extended to β-stable matter to explore the properties of the neutron star (NS). We analyse the DM effects on symmetric NM, pure neutron matter, and NS using NL3, G3, and IOPB-I forces. The binding energy per particle and pressure is calculated with and without considering the DM interaction with the NM systems. The influences of DM are also analysed on the symmetry energy and its different coefficients. The incompressibility and the skewness parameters are affected considerably due to the presence of DM in the NM medium. We extend the calculations to the NS and find its mass, radius and the moment of inertia for static and rotating NS with and without DM contribution. The mass of the rotating NS is considerably changing due to rapid rotation with the frequency in the mass-shedding limit. The effects of DM are found to be important for some of the NM parameters, which are crucial for the properties of astrophysical objects.

IMPACTS OF PARAMETERS ADJUSTMENT OF RELATIVISTIC MEAN FIELD MODEL ON NEUTRON STAR PROPERTIES

2011 ◽  
Vol 20 (05) ◽  
pp. 1271-1285 ◽  
Author(s):  
KASMUDIN ◽  
A. SULAKSONO
Keyword(s):  
Neutron Star ◽  
Reasonable Agreement ◽  
Field Model ◽  
Mean Field ◽  
Effective Field ◽  
Radiation Measurement ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
The Moment ◽  
Rmf Model

Analysis of the parameters adjustment effects in isovector as well as in isoscalar sectors of effective field based relativistic mean field (E-RMF) model in the symmetric nuclear matter and neutron-rich matter properties has been performed. The impacts of the adjustment on slowly rotating neutron star are systematically investigated. It is found that the mass–radius relation obtained from adjusted parameter set G2** is compatible not only with neutron stars masses from 4U 0614+09 and 4U 1636-536, but also with the ones from thermal radiation measurement in RX J1856 and with the radius range of canonical neutron star of X7 in 47 Tuc, respectively. It is also found that the moment inertia of PSR J073-3039A and the strain amplitude of gravitational wave at the Earth's vicinity of PSR J0437-4715 as predicted by the E-RMF parameter sets used are in reasonable agreement with the extracted constraints of these observations from isospin diffusion data.

scholarly journals Effects of dark matter on the in-spiral properties of the binary neutron stars

2021 ◽  
Vol 507 (3) ◽  
pp. 4053-4060
Author(s):  
H C Das ◽  
Ankit Kumar ◽  
S K Patra
Keyword(s):  
Dark Matter ◽  
Neutron Star ◽  
Mean Field ◽  
Time Duration ◽  
Mean Field Model ◽  
Binary Neutron Star ◽  
Relativistic Mean Field ◽  
Orbital Phase ◽  
High Fraction ◽  
Spiral Phase

ABSTRACT Using the relativistic mean-field model, we calculate the properties of binary neutron star (BNS) in the in-spiral phase. Assuming the dark matter (DM) particles are accreted inside the neutron star (NS) due to its enormous gravitational field, the mass M, radius R, tidal deformability λ, and dimensionless tidal deformability Λ are calculated at different DM fractions. The value of M, R, λ, and Λ decreases with the increase of DM percentage inside the NS. The in-spiral phase properties of the BNS are explored within the post-Newtonian (PN) formalism, as it is suitable up to the last orbits in the in-spiral phase. We calculate the strain amplitude of the polarization waveform h+ and h×, (2,2) mode waveform h22, orbital phase Φ, frequency of the gravitational wave f, and PN parameter x with DM as an extra candidate inside the NS. The magnitude of f, Φ, and x are almost the same for all assumed forces; however, the in-spiral time duration in the last orbit is different. We find that the BNS with soft equation of state and a high fraction of DM sustains more time in their in-spiral phase. We suggest that one should take DM inside the NS when they modelling the in-spiral waveforms for the BNS systems.

scholarly journals Effects of symmetry energy on the radius and tidal deformability of neutron stars in the relativistic mean-field model

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
Jinniu Hu ◽  
Shishao Bao ◽  
Ying Zhang ◽  
Ken’ichiro Nakazato ◽  
Kohsuke Sumiyoshi ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Symmetry Energy ◽  
Binary Star ◽  
Mean Field ◽  
Mass Region ◽  
Saturation Density ◽  
Coupling Constants ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
The Family

Abstract The radii and tidal deformabilities of neutron stars are investigated in the framework of the relativistic mean-field (RMF) model with different density-dependent behaviors of symmetry energy. To study the effects of symmetry energy on the properties of neutron stars, $\omega$ meson and $\rho$ meson coupling terms are included in a popular RMF Lagrangian, i.e., the TM1 parameter set, which is adopted for the widely used supernova equation of state (EoS) table. The coupling constants relevant to the vector–isovector meson, $\rho$, are refitted by a fixed symmetry energy at subsaturation density and its slope at saturation density, while other coupling constants remain the same as the original ones in TM1 so as to update the supernova EoS table. The radius and mass of maximum neutron stars are not so sensitive to the symmetry energy in these family TM1 parameterizations. However, the radii in the intermediate-mass region are strongly correlated with the slope of symmetry energy. Furthermore, the dimensionless tidal deformabilities of neutron stars are also calculated within the associated Love number, which is related to the quadrupole deformation of the star in a static external tidal field and can be extracted from the observation of a gravitational wave generated by a binary star merger. We find that its value at $1.4 \mathrm{M}_\odot$ has a linear correlation to the slope of symmetry energy, unlike that previously studied. With the latest constraints of tidal deformabilities from the GW170817 event, the slope of symmetry energy at nuclear saturation density should be smaller than $60$ MeV in the family TM1 parameterizations. This fact supports the usage of a lower symmetry energy slope for the updated supernova EoS, which is applicable to simulations of neutron star mergers. Furthermore, an analogous analysis is also done within the family IUFSU parameter sets. It is found that the correlations between the symmetry energy slope with the radius and tidal deformability at $1.4 \mathrm{M}_\odot$ have very similar linear relations in these RMF models.

scholarly journals A Modern View of the Equation of State in Nuclear and Neutron Star Matter

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 400
Author(s):  
G. Fiorella Burgio ◽  
Hans-Josef Schulze ◽  
Isaac Vidaña ◽  
Jin-Biao Wei
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Nuclear Matter ◽  
Symmetry Energy ◽  
Quantum Monte Carlo ◽  
Mean Field ◽  
Nuclear Symmetry Energy ◽  
Relativistic Mean Field ◽  
Monte Carlo Techniques ◽  
Nuclear Incompressibility

Background: We analyze several constraints on the nuclear equation of state (EOS) currently available from neutron star (NS) observations and laboratory experiments and study the existence of possible correlations among properties of nuclear matter at saturation density with NS observables. Methods: We use a set of different models that include several phenomenological EOSs based on Skyrme and relativistic mean field models as well as microscopic calculations based on different many-body approaches, i.e., the (Dirac–)Brueckner–Hartree–Fock theories, Quantum Monte Carlo techniques, and the variational method. Results: We find that almost all the models considered are compatible with the laboratory constraints of the nuclear matter properties as well as with the largest NS mass observed up to now, 2.14−0.09+0.10M⊙ for the object PSR J0740+6620, and with the upper limit of the maximum mass of about 2.3–2.5M⊙ deduced from the analysis of the GW170817 NS merger event. Conclusion: Our study shows that whereas no correlation exists between the tidal deformability and the value of the nuclear symmetry energy at saturation for any value of the NS mass, very weak correlations seem to exist with the derivative of the nuclear symmetry energy and with the nuclear incompressibility.

scholarly journals Core–crust transition properties of neutron stars within systematically varied extended relativistic mean-field model

2014 ◽  
Vol 23 (11) ◽  
pp. 1450072 ◽  
Author(s):  
A. Sulaksono ◽  
Naosad Alam ◽  
B. K. Agrawal
Keyword(s):  
Symmetry Energy ◽  
Transition Point ◽  
Mean Field ◽  
Energy Parameter ◽  
Transition Density ◽  
Saturation Density ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
The Core ◽  
Model Independent

The model dependence and the symmetry energy dependence of the core–crust transition properties for the neutron stars (NS) are studied using three different families of systematically varied extended relativistic mean field model. Several forces within each of the families are so considered that they yield wide variations in the values of the nuclear symmetry energy a sym and its slope parameter L at the saturation density. The core–crust transition density is calculated using a method based on random-phase-approximation. The core–crust transition density is strongly correlated, in a model independent manner, with the symmetry energy slope parameter evaluated at the saturation density. The pressure at the transition point does not show any meaningful correlations with the symmetry energy parameters at the saturation density. At best, pressure at the transition point is correlated with the symmetry energy parameters and their linear combination evaluated at the some sub-saturation density. Yet, such correlations might not be model independent. The correlations of core–crust transition properties with the symmetry energy parameter are also studied by varying the symmetry energy within a single model. The pressure at the transition point is correlated once again with the symmetry energy parameter at the sub-saturation density.

CONSTRAINING THE DENSITY DEPENDENCE OF THE SYMMETRY ENERGY WITH NUCLEAR STRUCTURE PROPERTIES

2010 ◽  
Vol 19 (08n09) ◽  
pp. 1720-1726
Author(s):  
WEI-ZHOU JIANG
Keyword(s):  
Nuclear Matter ◽  
Density Dependence ◽  
Symmetry Energy ◽  
Field Model ◽  
Mean Field ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
Finite Nuclei ◽  
The Relationship ◽  
Structure Properties

In this work, we review a few structural properties in finite nuclei and nuclear matter that are sensitive to differences in the symmetry energy, and discuss mechanisms that can enhance the sensitivity to differences in the symmetry energy with the relativistic mean-field model. Emphasis has been placed on the establishment of the relationship between the deexcitation energy of superdeformed secondary minima and the density dependence of the symmetry energy.

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