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Register a new userTides in merging neutron stars: Consistency of the GW170817 event with experimental data on finite nuclei
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The agreement of the nuclear equation of state (EoS) deduced from the GW170817 based tidal deformability with the one obtained from empirical data on microscopic nuclei is examined. It is found that suitably chosen experimental data on isoscalar and isovector modes of nuclear excitations together with the observed maximum neutron star mass constrain the EoS which displays a very good congruence with the GW170817 inspired one. The giant resonances in nuclei are found to be instrumental in limiting the tidal deformability parameter and the radius of neutron star in somewhat narrower bounds. At the 1$sigma$ level, the values of the canonical tidal deformability $Lambda_{1.4}$ and the neutron star radius $R_{1.4}$ come out to be $267pm144$ and $11.6pm1.0$ km, respectively.
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We study quark-hadron hybrid stars with sharp phase transitions assuming that phase
{it Background.} We investigate possible correlations between neutron star observables and properties of atomic nuclei. Particularly, we explore how the tidal deformability of a 1.4 solar mass neutron star, $M_{1.4}$, and the neutron skin thickness of ${^{48}}$Ca and ${^{208}}$Pb are related to the stellar radius and the stiffness of the symmetry energy. {it Methods.} We examine a large set of nuclear equations of state based on phenomenological models (Skyrme, NLWM, DDM) and {it ab-initio} theoretical methods (BBG, Dirac-Brueckner, Variational, Quantum Monte Carlo). {it Results.} We find strong correlations between tidal deformability and NS radius, whereas a weaker correlation does exist with the stiffness of the symmetry energy. Regarding the neutron skin thickness, weak correlations appear both with the stiffness of the symmetry energy, and the radius of a $M_{1.4}$. {it Conclusion.} The tidal deformability of a $M_{1.4}$ and the neutron-skin thickness of atomic nuclei show some degree of correlation with nuclear and astrophysical observables, which however depends on the ensemble of adopted EoS.
With the remarkable advent of gravitational-wave astronomy, we have shed light on previously shrouded events: compact binary coalescences. Neutron stars are promising (and confirmed) sources of gravitational radiation and it proves timely to consider the ways in which these stars can be deformed. Gravitational waves provide a unique window through which to examine neutron-star interiors and learn more about the equation of state of ultra-dense nuclear matter. In this work, we study two relevant scenarios for gravitational-wave emission: neutron stars that host (non-axially symmetric) mountains and neutron stars deformed by the tidal field of a binary partner. Although they have yet to be seen with gravitational waves, rotating neutron stars have long been considered potential sources. By considering the observed spin distribution of accreting neutron stars with a phenomenological model for the spin evolution, we find evidence for gravitational radiation in these systems. We study how mountains are modelled in both Newtonian and relativistic gravity and introduce a new scheme to resolve issues with previous approaches to this problem. The crucial component of this scheme is the deforming force that gives the star its non-spherical shape. We find that the force (which is a proxy for the stars formation history), as well as the equation of state, plays a pivotal role in supporting the mountains. Considering a scenario that has been observed with gravitational waves, we calculate the structure of tidally deformed neutron stars, focusing on the impact of the crust. We find that the effect on the tidal deformability is negligible, but the crust will remain largely intact up until merger.
The equation of state (EoS) of the neutron star (NS) matter remains an enigma. In this work we perform the Bayesian parameter inference with the gravitational wave data (GW170817) and mass-radius observations of some NSs (PSR J0030+0451, PSR J0437-4715, and 4U 1702-429) using the phenomenologically constructed EoS models to search for a potential first-order phase transition. Our phenomenological EoS models take the advantages of current widely used parametrizing methods, which are flexible enough to resemble various theoretical EoS models. We find that the current observation data are still not informative enough to support/rule out phase transition, due to the comparable evidences for models with and without phase transition. However, the bulk properties of the canonical $1.4,M_odot$ NS and the pressure at around $2rho_{rm sat}$ are well constrained by the data, where $rho_{rm sat}$ is the nuclear saturation density. Moreover, strong phase transition at low densities is disfavored, and the $1sigma$ lower bound of transition density is constrained to $1.84rho_{rm sat}$.
[Background]: In our previous paper, we predicted $r_{rm skin}$, $r_{rm p}$, $r_{rm n}$, $r_{rm m}$ for $^{40-60,62,64}$Ca after determining the neutron dripline, using the Gogny-D1S HFB with and without the angular momentum projection (AMP). We found that effects of the AMP are small. Very lately, Tanaka {it et al.} measured interaction cross sections $sigma_{rm I}$ for $^{42-51}$Ca, determined $r_{rm m}$ from the $sigma_{rm I}$, and deduced skin $r_{rm skin}$ and $r_{rm n}$ from the $r_{rm m}$ and the $r_{rm p}(rm {exp})$ evaluated from the electron scattering. Comparing our results with the data, we find for $^{42-48}$Ca that GHFB and GHFB+AMP reproduce the data on $r_{rm skin}$, $r_{rm n}$, $r_{rm m}$, but not for $r_{rm p}(rm {exp})$. [Aim]: Our purpose is to determine a value of $r_{rm skin}^{48}$ by using GHFB+AMP and the constrained GHFB (cGHFB) in which the calculated value is fitted to $r_{rm p}(rm {exp})$. [Results]: For $^{42,44,46,48}$Ca, cGHFB hardly changes $r_{rm skin}$, $r_{rm m}$, $r_{rm n}$ calculated with GHFB+AMP, except for $r_{rm skin}^{48}$. For $r_{rm skin}^{48}$, the cGHFB result is $r_{rm skin}^{48}=0.190$fm, while $r_{rm skin}^{48}=0.159$fm for GHFB+AMP. We should take the upper and the lower bound of GHFB+AMP and cGHFB. The result $r_{rm skin}^{48}=0.159-0.190$fm consists with the $r_{rm skin}^{48}(sigma_{rm I})$ and the data $r_{rm skin}^{48}(rm $E1$pE)$ obtained from high-resolution $E1$ polarizability experiment ($E1$pE). Using the $r_{rm skin}^{48}$-$r_{rm skin}^{208}$ relation with strong correlation of Ref.[3], we transform the data $r_{rm skin}^{208}$ determined by PREX and $E1$pE to the corresponding values, $r_{rm skin}^{48}(rm tPREX)$ and $r_{rm skin}^{48}(rm t$E1$pE)$. Our result is consistent also for $r_{rm skin}^{48}(rm tPREX)$ and $r_{rm skin}^{48}(rm t$E1$pE)$.
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