scholarly journals Phase Conversions in Neutron Stars: Implications for Stellar Stability and Gravitational Wave Astrophysics

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 493
Author(s):  
Germán Lugones ◽  
Ana Gabriela Grunfeld
Keyword(s):  
Physical Properties ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Quark Matter ◽  
Formation Mechanisms ◽  
New Class ◽  
Stellar Stability ◽  
Hybrid Stars ◽  
Stable Hybrid

We review the properties of hybrid stars with a quark matter core and a hadronic mantle, focusing on the role of key micro-physical properties such as the quark/hadron surface and curvature tensions and the conversion speed at the interface between both phases. We summarize the results of works that have determined the surface and curvature tensions from microscopic calculations. If these quantities are large enough, mixed phases are energetically suppressed and the quark core would be separated from the hadronic mantle by a sharp interface. If the conversion speed at the interface is slow, a new class of dynamically stable hybrid objects is possible. Densities tens of times larger than the nuclear saturation density can be attained at the center of these objects. We discuss possible formation mechanisms for the new class of hybrid stars and smoking guns for their observational identification.

NEW ASPECTS ON GRAVITATIONAL WAVE EMISSION BY NEUTRON STARS

2004 ◽  
Vol 13 (07) ◽  
pp. 1293-1296 ◽  
Author(s):  
GUILHERME F. MARRANGHELLO ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
JOSÉ A. de FREITAS PACHECO ◽  
MANFRED DILLIG ◽  
HÉLIO T. COELHO
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Quark Matter ◽  
Inner Core ◽  
Compact Objects ◽  
Wave Emission

We discuss, in this work, new aspects related to the emission of gravitational waves by neutron stars, which undergo a phase transition, from nuclear to quark matter, in its inner core. Such a phase transition would liberate around 1052–53 erg of energy in the form of gravitational waves which, if detected, may shed some light in the structure of these compact objects and provide new insights on the equation of state of nuclear matter.

scholarly journals Contraction of cold neutron star due to in the presence a quark core

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
B. Eslam Panah ◽  
T. Yazdizadeh ◽  
G. H. Bordbar
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Quark Matter ◽  
Average Density ◽  
Dynamical Stability ◽  
Hadronic Matter ◽  
Maximum Mass ◽  
Quark Core ◽  
Hybrid Stars ◽  
Schwarzschild Radius

Abstract Motivated by importance of the existence of quark matter on structure of neutron star. For this purpose, we use a suitable equation of state (EoS) which include three different parts: (i) a layer of hadronic matter, (ii) a mixed phase of quarks and hadrons, and, (iii) a strange quark matter in the core. For this system, in order to do more investigation of the EoS, we evaluate energy, Le Chatelier’s principle and stability conditions. Our results show that the EoS satisfies these conditions. Considering this EoS, we study the effect of quark matter on the structure of neutron stars such as maximum mass and the corresponding radius, average density, compactness, Kretschmann scalar, Schwarzschild radius, gravitational redshift and dynamical stability. Also, considering the mentioned EoS in this paper, we find that the maximum mass of hybrid stars is a little smaller than that of the corresponding pure neutron star. Indeed the maximum mass of hybrid stars can be quite close to the pure neutron stars. Our calculations about the dynamical stability show that these stars are stable against the radial adiabatic infinitesimal perturbations. In addition, our analyze indicates that neutron stars are under a contraction due to the existence of quark core.

scholarly journals Neutron star seismology

2012 ◽  
Vol 8 (S291) ◽  
pp. 159-159
Author(s):  
Nils Andersson
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Wave

AbstractI will provide an overview of recent improvements in our models for vibrating neutron stars, discussing the role of composition, heat, crust elasticity and superfluidity. I will explain how the results may impact on observations, in particular related to magnetar QPOs and future gravitational-wave searches.

scholarly journals Gravitational decoupling of generalized Horndeski hybrid stars

2022 ◽  
Vol 82 (1) ◽  
Author(s):  
Roldao da Rocha
Keyword(s):  
General Relativity ◽  
Physical Properties ◽  
Neutron Stars ◽  
Observational Data ◽  
White Dwarfs ◽  
Mass Function ◽  
Effective Radius ◽  
Asymptotic Value ◽  
Klein Gordon ◽  
Hybrid Stars

AbstractGravitational decoupled compact polytropic hybrid stars are here addressed in generalized Horndeski scalar-tensor gravity. Additional physical properties of hybrid stars are scrutinized and discussed in the gravitational decoupling setup. The asymptotic value of the mass function, the compactness, and the effective radius of gravitational decoupled hybrid stars are studied for both cases of a bosonic and a fermionic prevalent core. These quantities are presented and discussed as functions of Horndeski parameters, the decoupling parameter, the adiabatic index, and the polytropic constant. Important corrections to general relativity and generalized Horndeski scalar-tensor gravity, induced by the gravitational decoupling, comply with available observational data. Particular cases involving white dwarfs, boson stellar configurations, neutron stars, and Einstein–Klein–Gordon solutions, formulated in the gravitational decoupling context, are also scrutinized.

HYBRID STARS WITH DELTA MATTER AND COLOR–FLAVOR LOCKED QUARK PHASE

2008 ◽  
Vol 17 (05) ◽  
pp. 737-746 ◽  
Author(s):  
H. RODRIGUES ◽  
J. C. T. OLIVEIRA ◽  
S. B. DUARTE
Keyword(s):  
Phase Transition ◽  
Quark Matter ◽  
Strange Quark ◽  
Bose Condensate ◽  
Hadronic Matter ◽  
Hybrid Stars ◽  
S Quarks ◽  
Quark Phase ◽  
Color Superconductor

The color–flavor locked (CFL) phase is believed to be the fundamental state of strange quark matter (SQM) at high densities. The CFL phase is a color superconductor composed of pairs of u, d and s quarks, with no electrons, forming a Bose condensate. In this work, we analyze a possible phase transition of hadronic matter made of nucleons, Δ–resonances, hyperons and leptons, to CFL superconducting quark matter. An equation of state taking into account this phase transition is employed to determine the characteristics of a hybrid star. The role of the color superconducting gap on the hybrid stars properties is also discussed.

scholarly journals Simulating Binary Neutron Stars with Hybrid Equation of States: Gravitational Waves, Electromagnetic Signatures and Challenges for Numerical Relativity

Particles ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 365-384 ◽  
Author(s):  
Henrique Gieg ◽  
Tim Dietrich ◽  
Maximiliano Ujevic
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Quark Matter ◽  
Strange Quark ◽  
Numerical Relativity ◽  
Strange Quark Matter ◽  
Strong Phase ◽  
Equation Of States

The gravitational wave and electromagnetic signatures connected to the merger of two neutron stars allow us to test the nature of matter at supranuclear densities. Since the Equation of State governing the interior of neutron stars is only loosely constrained, there is even the possibility that strange quark matter exists inside the core of neutron stars. We investigate how strange quark matter cores affect the binary neutron star coalescence by performing numerical relativity simulations. Interestingly, the strong phase transition can cause a reduction of the convergence order of the numerical schemes to first order if the numerical resolution is not high enough. Therefore, an additional challenge is added in producing high-quality gravitational wave templates for Equation of States with a strong phase transition. Focusing on one particular configuration of an equal mass configuration consistent with GW170817, we compute and discuss the associated gravitational wave signal and some of the electromagnetic counterparts connected to the merger of the two stars. We find that existing waveform approximants employed for the analysis of GW170817 allow describing this kind of systems within the numerical uncertainties, which, however, are several times larger than for pure hadronic Equation of States, which means that even higher resolutions have been employed for an accurate gravitational wave model comparison. We also show that for the chosen Equation of State, quasi-universal relations describing the gravitational wave emission after the moment of merger seem to hold and that the electromagnetic signatures connected to our chosen setup would not be bright enough to explain the kilonova associated to GW170817.

scholarly journals Evolution of newborn neutron stars: role of quark matter nucleation

2011 ◽  
Vol 336 ◽  
pp. 012021
Author(s):  
Ignazio Bombaci ◽  
Domenico Logoteta ◽  
Constança Providencia ◽  
Isaac Vidaña
Keyword(s):  
Neutron Stars ◽  
Quark Matter
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