We investigate the peculiar nature of strange stars through an analysis of different quark models, i.e. vBag model and CFL model equation of states at different parameter sets, and focus on ...understanding the equation of state governing the intriguing central compact object (CCO) within the supernova remnant HESS J1731-347, with a mass and radius of
M
=
0
.
77
-
0.17
+
0.20
M
⊙
and
R
=
10
.
4
-
0.78
+
0.86
km, respectively. Additionally, we compare the radial oscillations of two models to determine the frequency of the HESS J1731-347 compact object at its maximum mass. The frequencies of radial oscillations are computed for each of the four EoSs considered. In total, the 10 lowest radial frequencies for each of those EoSs have been computed. By delving into these aspects, we aim at deepening our understanding of strange stars and their connection to the observed HESS J1731-347 mass-radius relationship.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
2.
Heavy Magnetic Neutron Stars Rather, Ishfaq A.; Rahaman, Usuf; Dexheimer, V. ...
Astrophysical journal/The Astrophysical journal,
08/2021, Volume:
917, Issue:
1
Journal Article
Peer reviewed
Open access
Abstract
We systematically study the properties of pure nucleonic and hyperonic magnetic stars using a density-dependent relativistic mean-field (DD-RMF) equations of state. We explore several ...parameter sets and hyperon coupling schemes within the DD-RMF formalism. We focus on sets that are in better agreement with nuclear and other astrophysical data while generating heavy neutron stars. Magnetic field effects are included in the matter equation of state and in general relativity solutions, which in addition fulfill Maxwell’s equations. We find that pure nucleonic matter, even without magnetic field effects, generates neutron stars that satisfy the potential GW 190814 mass constraint; however, this is not the case for hyperonic matter, which instead only satisfies the more conservative 2.1
M
⊙
constraint. In the presence of strong but still somehow realistic internal magnetic fields ≈10
17
G, the stellar charged particle population re-leptonizes and de-hyperonizes. As a consequence, magnetic fields stiffen hyperonic equations of state and generate more massive neutron stars, which can satisfy the possible GW 190814 mass constraint but present a large deformation with respect to spherical symmetry.
Abstract
The effects of strong magnetic fields on the deconfinement phase transition expected to take place in the interior of massive neutron stars are studied in detail for the first time. For ...hadronic matter, the very general density-dependent relativistic mean field model is employed, while the simple, but effective vector-enhanced bag model is used to study quark matter. Magnetic-field effects are incorporated into the matter equation of state and in the general-relativity solutions, which also satisfy Maxwell’s equations. We find that for large values of magnetic dipole moment, the maximum mass, canonical mass radius, and dimensionless tidal deformability obtained for stars using spherically symmetric Tolman–Oppenheimer–Volkoff (TOV) equations and axisymmetric solutions attained through the LORENE library differ considerably. The deviations depend on the stiffness of the equation of state and on the star mass being analyzed. This points to the fact that, unlike what was assumed previously in the literature, magnetic field thresholds for the approximation of isotropic stars and the acceptable use of TOV equations depend on the matter composition and interactions.
A comprehensive study is carried out on the impact of strong magnetic fields on the deconfinement phase transition inside massive neutron stars. The matter equation of state and the general ...relativity solutions, which also fulfill Maxwell’s equations, are modified when taking magnetic-field effects into account. We observe that the maximum mass and canonical-mass radius of stars computed using spherically-symmetric TOV equations and axisymmetric solutions obtained through the LORENE library differ significantly for large values of magnetic dipole moment. The discrepancies depend on the stellar mass being studied, as well as the stiffness of the equation of state. This indicates that the matter composition and interactions determine the magnetic field thresholds for the acceptable approximation of isotropic stars and the appropriate application of TOV equations.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract We study radial oscillations of hybrid neutron stars composed of hadronic external layers followed by a quark matter core. We employ a density-dependent relativistic mean-field model ...including hyperons and Δ baryons to describe hadronic matter, and a density-dependent quark model for quark matter. We obtain the ten lowest eigenfrequencies and the corresponding oscillation functions of N, N+Δ, N+H, and N+H+Δ equations-of-state with a phase transition to the quark matter at 1.4 and 1.8 M ⊙ , focusing on the effects of a slow phase transition at the hadron-quark interface. We observe that the maximum mass is reached before the fundamental mode's frequency vanishes for slow phase transitions, suggesting that some stellar configurations with higher central densities than the maximum mass remain stable even when they undergo small radial perturbations. Future gravitational wave detectors and multi-messenger astronomy, complemented by robust microscopic models enabling exploration of various neutron star compositions, including hyperon content, are anticipated to impose precise limitations on the equation of state of baryonic matter under high-density conditions.
The present study focuses on investigating the shape evolution of neutron-rich even-even osmium (Os) transitional nuclei within the range of neutron number N = 82 to N = 190. The investigation is ...conducted using density-dependent meson-nucleon and point-coupling models within the framework of the covariant density functional theory (CDFT). Additionally, the results obtained from the CDFT calculations are compared with those obtained using the relativistic mean-field model with a nonlinear meson-nucleon interaction. The potential energy curve for Os isotopes (ranging from
158
Os to
260
Os) is analyzed in order to identify phase shape transitions, such as oblate-spherical-prolate. Furthermore, ground state bulk properties are calculated to gain insights into the structure of Os isotopes. The self-consistent calculations reveal a clear shape transition in the even-even Os isotopes, and overall, good agreement is observed among the different models employed as well as with the available experimental data.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We study the nuclear matter properties like symmetry energy, slope parameter, curvature, skewness and incompressibility for hybrid EoS. The hybrid EoS is constructed by combining the hadron phase ...with the quark phase. For the hadron phase, we use the recently proposed effective-field-theory motivated relativistic mean-field model (E-RMF) with different parameter sets. For the quark phase, we employ the simple Massachusetts Institute of Technology bag model with different bag constants. The mixed phase formed by the hadron-quark phase transition is studied using the Gibbs construction. The nuclear matter properties for hybrid EoS are calculated and their variation with the bag constant is determined. Star matter properties like mass and radius are also calculated for the obtained EoS.
Within the axially deformed relativistic mean field with
NL3
∗
parametrisation, the different bulk properties like binding energy, quadrupole deformation parameter, separation energies, density ...profile and shape co-existence for
Z
= 119 isotopic chain within the mass range 284
≤
A
≤
375 are computed. Further, a competition between possible decay modes such as α-decay,
β
-decay and spontaneous fission (SF) of the isotopic chain of
Z
= 119 superheavy nuclei under study is systematically analysed within self-consistent relativistic mean field model and a close agreement is noticed among the calculations performed using various semi-empirical formulae and also with the estimations made by finite range droplet model (FRDM) wherever available. Our analysis confirmed that α–decay is restricted within the mass range 284
≤
A
≤
375 and thus being the dominant decay channel in this mass range and there is no possibility of
β
–decay for the considered isotopic chain. In addition, we forecasted the α–decay chain of fission survival nuclides, i.e.
284
-
296
119
and found as one α chain from
284
119
and
296
119
,
2
α
chains from
285
119
and
295
119
consistently,
3
α
chains from
286
119
and
294
119
consistently,
4
α
chains from
287
119
consistently, six consistent α chains from
288
-
293
119
. A comparative study of SF and α-decay half-live computed using the formula of Santhosh et al and Coulomb proximity potential model (CPPM), respectively, for the fission surviving isotopic chain reveals that isotopes
288
-
293
119
exhibit
6
α
chains followed by SF, isotopes
295
,
296
119
exhibit
4
α
chains followed by SF, and the rest of the nuclei show continuous α chains. This study has also established that the alpha half-life values computed using
Q
α
(RMF) agree with half-life values computed using experimental
Q
α
values within 1 order difference. Thus, such studies can be of great significance to the experimentalists in very near future for synthesizing the isotopes of
Z
= 119 superheavy nuclei.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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