Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userNeutron star deformability with hyperonization in density-dependent relativistic mean-field models
103
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Neutron star tidal deformability extracted from gravitational wave data provides a novel probe to the interior neutron star structures and the associated nuclear equation of state (EOS). Instead of the popular composition of nucleons and leptons in neutron stars, we include hyperons and examine the role of hyperons in the tidal deformability and its impact on the symmetry energy in a relativistic mean-field approach with the density-dependent parametrizations. The hyperons are found to have significant impact on the deformability, correlated sensitively with the onset density and fraction of hyperons in neutron star matter. Moderately lower onset density of hyperons can yield considerable modification to the tidal deformability and shift its inference on the nuclear EOS. The future measurements of the tidal deformability at multi-fiducial star masses are anticipated to lift the degeneracy between the contributions from the hyperon component and symmetry energy.
rate research
Read More
There is a growing interest in investigating modified theories of gravity, primarily, with the aim of explaining the universes accelerated expansion, which has been confirmed by several independent observations. Compact objects, like neutron stars, exhibit strong gravity effects and therefore are used to study modified gravity theories. We use the $f(R)=R+aR^2$ model, where R is the Ricci scalar and $a$ is a free parameter. This model has been studied both perturbatively and non-perturbatively. However, it was found that perturbative methods results in nonphysical solutions for the neutron stars. In this paper, we examine neutron star properties, such as mass, radius, tidal deformability in non-perturbative $f(R)$ gravity model with density dependant relativistic equation of state with different particle compositions. The strange particles in the core of NS in the form of ${bf Lambda}$ hyperons, $K^-$ condensate, and quarks are considered. We have observed that while the mass-radius relation allows for a wide range of parameter $a$, when tidal deformability is considered, the parameter $a$ is constrained down by one order.
The liquid-gas phase transition in hot asymmetric nuclear matter is studied within density-dependent relativistic mean-field models where the density dependence is introduced according to the Brown-Rho scaling and constrained by available data at low densities and empirical properties of nuclear matter. The critical temperature of the liquid-gas phase transition is obtained to be 15.7 MeV in symmetric nuclear matter falling on the lower edge of the small experimental error bars. In hot asymmetric matter, the boundary of the phase-coexistence region is found to be sensitive to the density dependence of the symmetry energy. The critical pressure and the area of phase-coexistence region increases clearly with the softening of the symmetry energy. The critical temperature of hot asymmetric matter separating the gas phase from the LG coexistence phase is found to be higher for the softer symmetry energy.
We explore the effects of strangeness and $Delta$ resonance in baryonic matter and compact stars within the relativistic-mean-field (RMF) models. The covariant density functional PKDD is adopted for $N$-$N$ interaction, parameters fixed based on finite hypernuclei and neutron stars are taken for the hyperon-meson couplings, and the universal baryon-meson coupling scheme is adopted for the $Delta$-meson couplings. In light of the recent observations of GW170817 with the dimensionless combined tidal deformability $197 leq bar{Lambda}leq 720$, we find it is essential to include the $Delta$ resonances in compact stars, and small $Delta$-$rho$ coupling $g_{rho Delta}$ is favored if the mass $2.27{}_{-0.15}^{+0.17} M_odot$ of PSR J2215+5135 is confirmed.
Based on relativistic mean field (RMF) models, we study finite $Lambda$-hypernuclei and massive neutron stars. The effective $N$-$N$ interactions PK1 and TM1 are adopted, while the $N$-$Lambda$ interactions are constrained by reproducing the binding energy of $Lambda$-hyperon at $1s$ orbit of $^{40}_{Lambda}$Ca. It is found that the $Lambda$-meson couplings follow a simple relation, indicating a fixed $Lambda$ potential well for symmetric nuclear matter at saturation densities, i.e., around $V_{Lambda} = -29.786$ MeV. With those interactions, a large mass range of $Lambda$-hypernuclei can be well described. Furthermore, the masses of PSR J1614-2230 and PSR J0348+0432 can be attained adopting the $Lambda$-meson couplings $g_{sigmaLambda}/g_{sigma N}gtrsim 0.73$, $g_{omegaLambda}/g_{omega N}gtrsim 0.80$ for PK1 and $g_{sigmaLambda}/g_{sigma N}gtrsim 0.81$, $g_{omegaLambda}/g_{omega N}gtrsim 0.90$ for TM1, respectively. This resolves the Hyperon Puzzle without introducing any additional degrees of freedom.
New effective $Lambda N$ interactions are proposed for the density dependent relativistic mean field model. The multidimensionally constrained relativistic mean field model is used to calculate ground state properties of eleven known $Lambda$ hypernuclei with $Age 12$ and the corresponding core nuclei. Based on effective $NN$ interactions DD-ME2 and PKDD, the ratios $R_sigma$ and $R_omega$ of scalar and vector coupling constants between $Lambda N$ and $NN$ interactions are determined by fitting calculated $Lambda$ separation energies to experimental values. We propose six new effective interactions for $Lambda$ hypernuclei: DD-ME2-Y1, DD-ME2-Y2, DD-ME2-Y3, PKDD-Y1, PKDD-Y2 and PKDD-Y3 with three ways of grouping and including these eleven hypernuclei in the fitting. It is found that the two ratios $R_sigma$ and $R_omega$ are correlated well and there holds a good linear relation between them. The statistical errors of the ratio parameters in these effective interactions are analyzed. These new effective interactions are used to study the equation of state of hypernuclear matter and neutron star properties with hyperons.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
