scholarly journals Hybrid stars from a constrained equation of state

2022 ◽  
Vol 258 ◽  
pp. 07001
Author(s):  
Márcio Ferreira ◽  
Renan Câmara Pereira ◽  
Constança Providência
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Observational Constraints ◽  
Quark Core ◽  
Quark Interaction ◽  
Constrained Equation ◽  
Strangeness Content ◽  
Low Mass ◽  
Hybrid Stars ◽  
Quark Phase

We determine, within a meta-model, the properties of the nuclear matter equation of state (EoS) that allow for a phase transition to deconfinement matter. It is shown that the properties that define the isoscalar channel are the ones that are affected, in particular, a phase transition implies much larger values of the skewness and kurtosis. The effect of multi-quark interaction channels in the description of the quark phase in hybrid stars is also studied. NS properties, such as the mass and radius of the quark core, show an interplay dependence between the 8-quark vector and the 4-quark isovector-vector interactions. We show that low mass NS, M ~ 1.4M⊙, may already contain a quark core, and satisfy all existing NS observational constraints. We discuss the strangeness content of the quark core and its influence on the speed of sound.

scholarly journals INVESTIGATION OF THE EXISTENCE OF HYBRID STARS USING NAMBU–JONA–LASINIO MODELS

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1521-1524 ◽  
Author(s):  
J. G. COELHO ◽  
C. H. LENZI ◽  
M. MALHEIRO ◽  
R. M. MARINHO ◽  
M. FIOLHAIS
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Quark Matter ◽  
Chemical Potential ◽  
Compact Stars ◽  
Vector Coupling ◽  
Njl Model ◽  
Hybrid Stars ◽  
Quark Phase

We investigate the hadron-quark phase transition inside neutron stars and obtain mass–radius relations for hybrid stars. The equation of state for the quark phase using the standard NJL model is too soft, leading to an unstable star and suggesting a modification of the NJL model by introducing a momentum cutoff dependent on the chemical potential. However, even in this approach, the instability remains. In order to remedy the instability we suggest the introduction of a vector coupling in the NJL model, which makes the EoS stiffer, reducing the instability. We conclude that the possible existence of quark matter inside the stars require high densities, leading to very compact stars.

scholarly journals Constraints on the hybrid equation of state with a crossover hadron-quark phase transition in the light of GW170817

2018 ◽  
Vol 98 (8) ◽  
Author(s):  
Cheng-Ming Li ◽  
Yan Yan ◽  
Jin-Jun Geng ◽  
Yong-Feng Huang ◽  
Hong-Shi Zong
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Quark Phase

scholarly journals NON-UNIFORM STRUCTURE OF MATTER AND THE EQUATION OF STATE

2008 ◽  
Vol 17 (09) ◽  
pp. 1774-1789
Author(s):  
TOSHIKI MARUYAMA ◽  
SATOSHI CHIBA ◽  
TOSHITAKA TATSUMI
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Coulomb Repulsion ◽  
Mixed Phase ◽  
Uniform Structure ◽  
Kaon Condensation ◽  
Maxwell Construction ◽  
Two Phases ◽  
First Order Phase ◽  
Quark Phase

We investigate the non-uniform structures and the equation of state (EOS) of nuclear matter in the context of the first-order phase transitions (FOPT) such as liquid-gas phase transition, kaon condensation, and hadron-quark phase transition. During FOPT the mixed phases appear, where matter exhibits non-uniform structures called "Pasta" structures due to the balance of the Coulomb repulsion and the surface tension between two phases. We treat these effects self-consistently, properly taking into account of the Poisson equation and the Gibbs conditions. Consequently, they make the EOS of the mixed phase closer to that of Maxwell construction due to the Debye screening. This is a general feature of the mixed phase consisting of many species of charged particles.

scholarly journals Detecting the Hadron-Quark Phase Transition with Gravitational Waves

Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 156 ◽  
Author(s):  
Matthias Hanauske ◽  
Luke Bovard ◽  
Elias Most ◽  
Jens Papenfort ◽  
Jan Steinheimer ◽  
...  
Keyword(s):  
Phase Transition ◽  
Neutron Star ◽  
Equation Of State ◽  
Gravitational Wave ◽  
Compact Star ◽  
Binary Neutron Star ◽  
Interesting Part ◽  
Merger Event ◽  
Tidal Deformations ◽  
Quark Phase

The long-awaited detection of a gravitational wave from the merger of a binary neutron star in August 2017 (GW170817) marks the beginning of the new field of multi-messenger gravitational wave astronomy. By exploiting the extracted tidal deformations of the two neutron stars from the late inspiral phase of GW170817, it is now possible to constrain several global properties of the equation of state of neutron star matter. However, the most interesting part of the high density and temperature regime of the equation of state is solely imprinted in the post-merger gravitational wave emission from the remnant hypermassive/supramassive neutron star. This regime was not observed in GW170817, but will possibly be detected in forthcoming events within the current observing run of the LIGO/VIRGO collaboration. Numerous numerical-relativity simulations of merging neutron star binaries have been performed during the last decades, and the emitted gravitational wave profiles and the interior structure of the generated remnants have been analysed in detail. The consequences of a potential appearance of a hadron-quark phase transition in the interior region of the produced hypermassive neutron star and the evolution of its underlying matter in the phase diagram of quantum cromo dynamics will be in the focus of this article. It will be shown that the different density/temperature regions of the equation of state can be severely constrained by a measurement of the spectral properties of the emitted post-merger gravitational wave signal from a future binary compact star merger event.

HADRON-QUARK PHASE TRANSITION AND ANTIKAON CONDENSATION IN NEUTRON STARS

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2481-2484
Author(s):  
H. SHEN ◽  
F. YANG ◽  
P. YUE
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Mean Field Theory ◽  
Mean Field ◽  
Maximum Mass ◽  
Relativistic Mean Field ◽  
The Core ◽  
Quark Phase

We study the hadron-quark phase transition and antikaon condensation which may occur in the core of massive neutron stars. The relativistic mean field theory is used to describe the hadronic phase, while the Nambu-Jona-Lasinio model is adopted for the quark phase. We find that the hadron-quark phase transition is very sensitive to the models used. The appearance of deconfined quark matter and antikaon condensation can soften the equation of state at high density and lower the maximum mass of neutron stars.

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 Does a hadron-quark phase transition in dense matter preclude the existence of massive neutron stars?

2012 ◽  
Vol 8 (S291) ◽  
pp. 356-358 ◽  
Author(s):  
N. Chamel ◽  
A. F. Fantina ◽  
J. M. Pearson ◽  
S. Goriely
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Energy ◽  
Dense Matter ◽  
Density Functionals ◽  
Nuclear Mass ◽  
Neutron Star Mass ◽  
The Impact ◽  
Quark Phase

AbstractWe study the impact of a hadron-quark phase transition on the maximum neutron-star mass. The hadronic part of the equation of state relies on the most up-to-date Skyrme nuclear energy density functionals, fitted to essentially all experimental nuclear mass data and constrained to reproduce the properties of infinite nuclear matter as obtained from microscopic calculations using realistic forces. We show that the softening of the dense matter equation of state due to the phase transition is not necessarily incompatible with the existence of massive neutron stars like PSR J1614–2230.

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