Dimensionless Tidal Deformability Research Articles

Probing the impact of delta-baryons on nuclear matter and non-radial oscillations in neutron stars

Non-radial oscillations of Neutron Stars (NSs) provide a means to learn important details regarding their interior composition and equation of state. We consider the effects of Δ-baryons on non-radial f-mode oscillations and other NS properties within the Density-Dependent Relativistic Mean Field formalism. Calculations are performed for Δ-admixed NS matter with and without hyperons. Our study of the non-radial f-mode oscillations revealed a distinct increase in frequency due to the addition of the Δ-baryons with upto 20% increase in frequency being seen for canonical NSs. Other bulk properties of NSs, including mass, radii, and dimensionless tidal deformability (Λ) were also affected by these additional baryons. Comparing our results with available observational data from pulsars (NICER) and gravitational waves (LIGO-VIRGO collaboration), we found strong agreement, particularly concerning Λ.

The impact of anisotropy on neutron star properties: insights from 𝖨–𝖿–𝖢 universal relations

Anisotropy in pressure within a star emerges from exotic internal processes. In this study, we incorporate pressure anisotropy using the Quasi-Local model. Macroscopic properties, including mass (M), radius (R), compactness (C), dimensionless tidal deformability (Λ), the moment of inertia (I), and oscillation frequency (f), are explored for the anisotropic neutron star. Magnitudes of these properties are notably influenced by anisotropy degree. Universal I–f–C relations for anisotropic stars are explored in this study. The analysis encompasses various EOS types, spanning from relativistic to non-relativistic regimes. Results show the relation becomes robust for positive anisotropy, weakening with negative anisotropy. The distribution of f-mode across M–R parameter space as obtained with the help of C–f relation was analyzed for different anisotropic cases. Using tidal deformability data from GW170817 and GW190814 events, a theoretical limit for canonical f-mode frequency is established for isotropic and anisotropic neutron stars. For isotropic case, canonical f-mode frequency for GW170817 event is f 1.4 = 2.606+0.457 -0.484kHz; for GW190814 event, it is f 1.4 = 2.097+0.124 -0.149kHz. These relationships can serve as reliable tools for constraining nuclear matter EOS when relevant observables are measured.

Quark stars in massive gravity might be candidates for the mass gap objects

We have investigated the structural properties of strange quark stars (SQSs) in a modified theory of gravity known as massive gravity. In order to obtain the equation of state (EOS) of strange quark matter, we have employed a modified version of the Nambu–Jona-Lasinio model (MNJL) which includes a combination of NJL Lagrangian and its Fierz transformation by using weighting factors (1-α)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(1-\\alpha )$$\\end{document} and α.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha .$$\\end{document} Additionally, we have also calculated dimensionless tidal deformability (Λ)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\Lambda )$$\\end{document} in massive gravity. To constrain the allowed values of the parameters appearing in massive gravity, we have imposed the condition Λ1.4M⊙≲580.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _{1.4 {M}_{\\odot }}\\lesssim 580 .$$\\end{document} Notably, in the MNJL model, the value of α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha $$\\end{document} varies between zero and one. As α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha $$\\end{document} increases, the EOS becomes stiffer, and the value of Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda $$\\end{document} increases accordingly. We have demonstrated that by softening the EOS with increasing the bag constant, one can obtain objects in massive gravity that not only satisfy the constraint Λ1.4M⊙≲580,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _{1.4 {M} _{\\odot }}\\lesssim 580,$$\\end{document} but they also fall within the unknown mass gap region (2.5M⊙-5M⊙).\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(2.5{M}_{\\odot }-5{M}_{\\odot }).$$\\end{document} To establish that the obtained objects in this region are not black holes, we have calculated Schwarzschild radius, compactness, and ΛMTOV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _{{M_{TOV}}}$$\\end{document} in massive gravity.

New equations of state for dense nuclear matter properties

In the present work, we investigate the bulk properties of nuclear matter and neutron stars with the newly proposed relativistic parametrizations HPUA, HPUB and HPUC which provides an opportunity to readjust the coupling parameters keeping in view the properties of finite nuclei, nuclear matter and astrophysical constraints. The HPUA, HPUB and HPUC are proposed by fitting both PREX-II + CREX results simultaneously, PREX-II and CREX results for neutron skin thickness of 208Pb and 48Ca respectively to assess their implications. The relativistic parameterizations have been generated by including non linear self-interactions of σ and ω- mesons and mixed interactions of ω, and ρ-meson up to the quartic order. The new equations of state (EoSs) composed of nucleons and leptons in β - equilibrium are constructed with the newly proposed parameter sets. The maximum mass of the neutron star by employing the EoSs computed with the HPU's parameter sets lies in the range 2.02±0.03 M⊙ - 2.04±0.03 M⊙ and the radius of canonical neutron star (R1.4) comes out to be equal to 12.89±0.08 Km - 13.27±0.30 Km (including BPS crust). The value of dimensionless tidal deformability, for canonical mass, is 590.83±22.58 - 631.52±78.13 which satisfies the constraints of waveform models analysis of GW170817. A covariance analysis is also performed to calculate the statistical uncertainties in the model parameters and nuclear matter observables along with their correlations.

Bayesian analysis of a relativistic hadronic model constrained by recent astrophysical observations

ABSTRACTWe use Bayesian analysis in order to constrain the equation of state for nuclear matter from astrophysical data related to the recent measurements from the NICER mission, LIGO/Virgo collaboration, and probability distributions of mass and radius from other 12 sources, including thermonuclear busters, and quiescent low-mass X-ray binaries. For this purpose, we base our study on a relativistic hadronic mean field model including an ω − ρ interaction. Our results indicate optimal ranges for some bulk parameters at the saturation density, namely, effective mass, incompressibility, and symmetry energy slope (L0). For instance, we find $L_0 = 50.79^{+15.16}_{-9.24}$ MeV (Case 1) and $L_0 = 75.06^{+8.43}_{-4.43}$ MeV (Case 2) in a 68 per cent confidence interval for the two cases analysed (different input ranges for L0 related to the PREX-II data). The respective parametrizations are in agreement with important nuclear matter constraints, as well as observational neutron star data, such as the dimensionless tidal deformability of the GW170817 event. From the mass–radius curves obtained from these best parametrizations, we also find the ranges of 11.97 km ≤ R1.4 ≤ 12.73 km (Case 1) and 12.34 km ≤ R1.4 ≤ 13.06 km (Case 2) for the radius of the $1.4\, \mathrm{M}_\odot$ neutron star.

Universal relations to measure neutron star properties from targeted r-mode searches

ABSTRACT R-mode oscillations of rotating neutron stars (NS) are promising candidates for continuous gravitational wave (GW) observations. In our recent work, we derived universal relations between the NS parameters compactness and dimensionless tidal deformability with the r-mode frequency. In this work, we investigate how these universal relations can be used to infer various NS intrinsic parameters following a successful detection of the r-modes. In particular, we show that for targeted r-mode searches, these universal relations along with the ‘I–Love–Q’ relation can be used to estimate both the moment of inertia and the distance of the NS, thus breaking the degeneracy of distance measurement for continuous gravitational wave (CGW) observations. We also discuss that, with a prior knowledge of the distance of the NS from electromagnetic observations, these universal relations can also be used to constrain the dense matter equation of state (EOS) inside the NS. We quantify the accuracy to which such measurements can be done using the Fisher information matrix for a broad range of possible, unknown parameters for both the a-LIGO and Einstein Telescope (ET) sensitivities.

Recent astrophysical observations reproduced by a short-range correlated van der Waals-type model?

ABSTRACT We perform an improvement in a van der Waals-type model by including its effects of short-range correlations (SRCs). Attractive and repulsive parts of the nucleon–nucleon interaction are assumed to be density-dependent functions, more specifically, we adopt the Carnahan–Starling (CS) method for the latter, and a suitable expression for the former in order to reproduce the structure of the Clausius (C) real gas model. The parametrizations of the resulting model, named as Clausius-–Carnahan–Starling (CCS)-SRC model, are shown to be capable of reproducing the flow constraint at the high-density regime of symmetric nuclear matter for incompressibility values inside the range of K0 = (240 ± 20) MeV. In the context of stellar matter, our findings point out a good agreement of the CCS-SRC model with recent astrophysical observational data, namely, mass–radius contours and dimensionless tidal deformability regions and values, coming from gravitational waves data related to the GW170817 and GW190425 events, and from the NASA’s Neutron star Interior Composition Explorer mission. Furthermore, the values for the symmetry energy slope of the model (L0) are in agreement with a recent range found for this quantity, claimed to be consistent with results reported by the updated lead radius experiment (PREX-2) collaboration. In this case, higher values of L0 are favoured, while the opposite scenario does not allow simultaneous compatibility between the model and the astrophysical data.

Impact of O4 future detections on the determination of the dense matter equations of state

In view of the next LIGO-Virgo-KAGRA Observing period O4 (to start in Spring 2023), we address the question of the ability of the interferometers network to discriminate among different neutron stars equation of states better than what was possible with the observation of the binary neutron stars merger GW170817. We show that the observation of an event similar to GW170817 during O4 would allow us to resolve the dimensionless effective tidal deformability $\stackrel{\texttildelow{}}{\mathrm{\ensuremath{\Lambda}}}$ within an uncertainty 7 times better than the one obtained in O2. Thanks to the expected increase in sensitivities, we show that any GW170817-like single-event within a distance of 100 Mpc would imply significantly improved constraints of the neutron stars equations of state. We also illustrate the important impact of the noise in the analysis of the signal, showing how it can impact the effective tidal deformability probability density function for large signal-to-noise ratio.

Observational constraint from the heaviest pulsar PSR J0952-0607 on the equation of state of dense matter in relativistic mean field model

In the present work, we constrain the equation of state of dense matter in the context of heaviest observed neutron-star mass ${M}_{\mathrm{max}}=(2.35\ifmmode\pm\else\textpm\fi{}0.17){M}_{\ensuremath{\bigodot}}$ for the black widow pulsar PSR J0952-0607. We propose three interactions HPU1, HPU2 and HPU3 (named after Himachal Pradesh University) for the relativistic mean-field model, which include different combinations of nonlinear, self-couplings, and cross couplings among isoscalar-scalar $\ensuremath{\sigma}$, and isoscalar-vector $\ensuremath{\omega}$ and isovector-vector $\ensuremath{\rho}$ meson fields up to the quartic order. These interactions are in harmony with the finite nuclei and bulk nuclear matter properties. The equations of state computed by using newly generated interactions for the $\ensuremath{\beta}$-equilibrated nucleonic matter satisfy the heaviest observed neutron-star mass ${M}_{\mathrm{max}}=(2.35\ifmmode\pm\else\textpm\fi{}0.17){M}_{\ensuremath{\bigodot}}$ for the black widow pulsar PSR J0952-0607. The results for the radius ${R}_{1.4}$ and dimensionless tidal deformability ${\mathrm{\ensuremath{\Lambda}}}_{1.4}$ corresponding to the canonical mass are also presented and agree well with the GW170817 event and astrophysical observations. The radius of $2.08{M}_{\ensuremath{\bigodot}}$ neutron-star mass is predicted to be in the range ${R}_{2.08}=12.98$--13.09 km which also satisfy the NICER observations by Miller et al. [Astrophys. J. Lett. 918, L28 (2021)] and Riley et al. [Astrophys. J. Lett. 918, L27 (2021)]. A covariance analysis is also performed to assess the theoretical uncertainties of model parameters and to determine their correlations with nuclear matter observables.

Universal relations and finite temperature neutron stars

In the past few years, a lot of studies devoted to the discovery of universal relations (equation of state independent relations). The significance of such expressions can be understood if we consider that they offer the opportunity for testing general relativity in a way that is independent of the nuclear equation of state and they also allow us to impose constraints on the structure of neutron stars. The aim of this work is twofold. Firstly, we wish to clarify if hot equations of state are able to reproduce established universal relations. Secondly, we investigate a possible universal connection between the binding energy and the dimensionless tidal deformability of a neutron star. These two bulk properties are associated with two very important candidates for multimessenger signals, binary neutron star mergers and supernova explosions. We find that the predictions of hot equations of state do not agree with the predictions from accepted universal relations. Subsequently, the use of universal relations, when thermal effects are present, may be erroneous. Additionally, we find that, for moderate neutron star masses, the binding energy and the dimensionless tidal deformability of a neutron star satisfy a universal relation. The latter allows us to impose constraints on the binding energy of 1.4 Msun neutron star, using information from the analysis of the GW170817 event. Finally, we are able to present a universal relation between the compactness, the binding energy and the dimensionless tidal deformability, which is independent of the employed equation of state for zero and finite temperature.

Phase transition and stiffer core fluid in neutron stars: effects on stellar configurations, dynamical stability, and tidal deformability

In this work, we investigate the influence of the phase transition and a stiffer fluid in neutron stars’ cores on the static equilibrium configuration, dynamical stability, and tidal deformability. For this aim, it is taken into account that the fluid in the core and the envelope follow the relativistic polytropic equation of state. We find that the phase transition and a stiffer fluid in the core will reflect in the total mass, radius, speed of sound, core radius, radial stability with a slow and rapid conversion at the interface, and tidal deformability. We also investigate the dimensionless tidal deformability varLambda _1 and varLambda _2 for a binary neutron stars system with chirp mass equal to GW170817. Finally, we contrast our results with observational data to show the role that phase transition and a stiffer core fluid could play in the study of neutron stars.

Relativistic Correction to the r-mode Frequency in Light of Multimessenger Constraints

The r-mode oscillations of rotating neutron stars are promising candidates for continuous gravitational-wave (GW) observations. The r-mode frequencies for slowly rotating Newtonian stars are well known and independent of the equation of state (EOS), but for neutron stars several mechanisms can alter the r-mode frequency for which the relativistic correction is dominant and relevant for most of the neutron stars. The most sensitive searches for continuous GWs are those for known pulsars for which GW frequencies are in targeted narrow frequency bands of a few hertz. In this study, we investigate the effect of several state-of-the-art multimessenger constraints on the r-mode frequency for relativistic, slowly rotating, barotropic stars. Imposing these recent constraints on the EOS, we find that the r-mode frequency range is slightly higher than that from the previous study and the narrowband frequency range can increase by up to 25% for the most promising candidate PSR J0537−6910 depending on the range of compactness. We also derive universal relations between r-mode frequency and dimensionless tidal deformability that can be used to estimate the dynamical tide of the r-mode resonant excitation during the inspiral signal. These results can be used to construct the parameter space for r-mode searches in GW data and also constrain the nuclear EOS following a successful r-mode detection.

Radial pulsations, moment of inertia and tidal deformability of dark energy stars

We construct dark energy stars with Chaplygin-type equation of state (EoS) in the presence of anisotropic pressure within the framework of Einstein gravity. From the classification established by Iyer et al. (Class Quantum Grav 2:219, 1985), we discuss the possible existence of isotropic dark energy stars as compact objects. However, there is the possibility of constructing ultra-compact stars for sufficiently large anisotropies. We investigate the stellar stability against radial oscillations, and we also determine the moment of inertia and tidal deformability of these stars. We find that the usual static criterion for radial stability dM/drho _c >0 still holds for dark energy stars since the squared frequency of the fundamental pulsation mode vanishes at the critical central density corresponding to the maximum-mass configuration. The dependence of the tidal Love number on the anisotropy parameter alpha is also examined. We show that the surface gravitational redshift, moment of inertia and dimensionless tidal deformability undergo significant changes due to anisotropic pressure, primarily in the high-mass region. Furthermore, in light of the detection of gravitational waves GW190814, we explore the possibility of describing the secondary component of such event as a stable dark energy star in the presence of anisotropy.

Relativistic approach for the determination of nuclear and neutron star properties in consideration of PREX-II results

The bulk properties of nuclear matter and neutron stars with the newly generated relativisticinteraction Dev Bhoomi Himachal Pradesh (DBHP) are investigated, which provides an opportunity to modify the coupling parameters keeping in view the finite nuclei, nuclear matter, PREX-II data for neutron skin thickness in $^{208}\mathrm{Pb}$, and astrophysical constraints. The relativistic interaction has been generated by including all possible self and mixed interactions among $\ensuremath{\sigma}$, $\ensuremath{\omega}$, and $\ensuremath{\rho}$ mesons up to the quartic order satisfying the naturalness behavior of parameters. A covariance analysis is performed to assess the statistical uncertainties of the model parameters and observables of interest along with correlations amongst them. We obtained a value of neutron skin thickness for the $^{208}\mathrm{Pb}$ nucleus of $\mathrm{\ensuremath{\Delta}}{r}_{\mathrm{np}}=0.24\ifmmode\pm\else\textpm\fi{}0.02$ fm. The maximum gravitational mass of a neutron star and the radius corresponding to the canonical mass (${R}_{1.4}$) come out to be $2.03\ifmmode\pm\else\textpm\fi{}0.04$ ${M}_{\ensuremath{\bigodot}}$ and $13.39\ifmmode\pm\else\textpm\fi{}0.41$ km, respectively. The dimensionless tidal deformability $\mathrm{\ensuremath{\Lambda}}$ for a neutron star is also analyzed.

Magnetic-field Induced Deformation in Hybrid Stars

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.

Constraining mass, radius, and tidal deformability of compact stars with axial wI modes: new universal relations including slow stable hybrid stars

ABSTRACT We revisit asteroseismology with quadrupolar wI modes and present universal relationships for its fundamental and first overtone. In contrast to relationships proposed in the literature, our universal relationships are capable of including slow stable hybrid stars that appear when considering slow sharp hadron-quark phase transitions. We show that if the frequency and damping time of the fundamental mode of a given pulsating object are measured, its mass, radius, and dimensionless tidal deformability can be inferred. Moreover, we show that the errors of such estimates are smaller than a few per cent for the mass and radius. For the dimensionless tidal deformability, the errors are – for compact objects with $M\gtrsim 1.4\, \mathrm{M}_\odot$ – in general smaller than $\sim 100 \, {{\ \rm per\ cent}}$. Comparison with previous universal relationships shows that the ones proposed in this work produce better estimates of the mass and radius of totally stable compact objects.

Strange stars confronting with the observations: Non‐Newtonian gravity effects, or the existence of a dark‐matter core

AbstractWe find that the existence of strange stars is ruled out by the dimensionless tidal deformability of a star of GW170817 and the mass of PSR J0740 + 6620, both for the standard MIT bag model and for the density‐dependent quark mass model. However, if non‐Newtonian gravity effects are considered, strange stars can exist for certain ranges of the values of the non‐Newtonian gravity parameter. An alternative explanation to these observations is to suppose that strange stars in GW170817 have a dark‐matter core.

I−Love−C relation for an anisotropic neutron star

One of the most common assumptions has been made that the pressure inside the star is isotropic in nature. However, the pressure is locally anisotropic in nature which is a more realistic case. In this study, we investigate certain properties of anisotropic neutron stars with the scalar pressure anisotropy model. Different perfect fluid conditions are tested within the star with the relativistic mean-field model equation of states (EOSs). The anisotropic neutron star properties such as mass ($M$), radius ($R$), compactness ($C$), Love number ($k_2$), dimensionless tidal deformability ($\Lambda$), and the moment of inertia ($I$) are calculated. The magnitude of the quantities as mentioned above increases (decreases) with the positive (negative) value of anisotropy except $k_2$ and $\Lambda$. The Universal relation $I-$Love$-C$ is calculated with almost 58 EOSs spans from relativistic to non-relativistic cases. We observed that the relations between them get weaker when we include anisotropicity. With the help of the GW170817 tidal deformability limit and radii constraints from different approaches, we find that the anisotropic parameter is less than 1.0 if one uses the BL model. Using the universal relation and the tidal deformability bound given by the GW170817, we put a theoretical limit for the canonical radius, $R_{1.4}=10.74_{-1.36}^{+1.84}$ km, and the moment of inertia, $I_{1.4} = 1.77_{-0.09}^{+0.17}\times10^{45}$ g cm$^2$ with 90\% confidence limit for isotropic stars. Similarly, for anisotropic stars with $\lambda_{\rm BL}=1.0$, the values are $R_{1.4}=11.74_{-1.54}^{+2.11}$ km, $I_{1.4} = 2.40_{-0.08}^{+0.17} \times10^{45}$ g cm$^2$ respectively.

Dark particle mass effects on neutron star properties from a short-range correlated hadronic model

ABSTRACT In this work we study a relativistic mean-field (RMF) hadronic model, with nucleonic short-range correlations (SRC) included, coupled to dark matter (DM) through the Higgs boson. We study different parametrizations of this model by running the dark particle Fermi momentum, and its mass in the range of 50GeV ≤ Mχ ≤ 500GeV, compatible with experimental spin-independent scattering cross-sections. By using this RMF-SRC-DM model, we calculate some neutron star quantities, namely, mass–radius profiles, dimensionless tidal deformabilities, and crustal properties. Our findings show that is possible to construct RMF-SRC-DM parametrizations in agreement with constraints provided by LIGO and Virgo collaboration (LVC) on the GW170817 event, and recent observational data from the NICER mission. Furthermore, we show that the increase of Mχ favors the model to attain data from LVC regarding the tidal deformabilities. Higher values of Mχ also induce a reduction of the neutron star crust (mass and thickness), and cause a decrease of the crustal fraction of the moment of inertia (Icrust/I). Nevertheless, we show that some RMF-SRC-DM parametrizations still exhibit $I_{{\rm crust}}/I\gt 7{{\ \rm per\ cent}}$, a condition that explains the glitch activity in rotation-powered pulsars such as the Vela one. Therefore, dark matter content can also be used for describing such a phenomenon.

Effects of an isovector scalar meson on the equation of state of dense matter within a relativistic mean field model

The effects of the isovector-scalar $\delta$-meson field on the properties of finite nuclei, infinite nuclear matter and neutron stars are investigated within the Relativistic Mean Field (RMF) model which includes non-linear couplings. Several parameter sets (SRV's) are generated to asses the influence of $\delta$-meson on the properties of neutron star. These parametrizations correspond to different values of coupling constant of $\delta$-meson to the nucleons with remaining ones calibrated to yield finite nuclei and infinite nuclear matter properties consistent with the available experimental data. It is observed that to fit the properties of finite nuclei and infinite nuclear matter, a stronger coupling between isovector-vector $\rho$ meson and nucleons is required in the presence of $\delta$ field. Furthermore, the $\delta$-meson is found to affect the radius of canonical neutron star significantly. The value of dimensionless tidal deformability, ${\Lambda}$ for the canonical neutron star also satisfies the constraints from the waveform models analysis of GW170817 binary neutron star merger event. A covariance analysis is performed to estimate the statistical uncertainties of the model parameters as well as correlations among the model parameters and different observables of interest.