scholarly journals Metastable hypermassive hybrid stars as neutron-star merger remnants

2021 ◽  
Author(s):  
Matthias Hanauske ◽  
Lukas R. Weih ◽  
Horst Stöcker ◽  
Luciano Rezzolla
Keyword(s):  
Phase Transition ◽  
Quark Matter ◽  
Phase Region ◽  
Compact Stars ◽  
Spatial Density ◽  
Astrophysical Objects ◽  
Hybrid Stars ◽  
Inner Region ◽  
Mixed Phase Region

AbstractHypermassive hybrid stars (HMHS) are extreme astrophysical objects that could be produced in the merger of a binary system of compact stars. In contrast to their purely hadronic counterparts, hypermassive neutron stars (HMNS), these highly differentially rotating objects contain deconfined strange quark matter in their slowly rotating inner region. HMHS and HMNS are both mestastable configurations and can survive only shortly after the merger before collapsing to rotating black holes. The appearance of the phase transition from hadronic to quark matter in the interior region of the HMHS and its conjunction with the emitted GW will be addressed in this article by focussing on a specific case study of the delayed phase-transition scenario that takes place during the post-merger evolution of the remnant. The complicated dynamics of the collapse from the HMNS to the more compact HMHS will be analysed in detail. In particular, we will show that the interplay between the spatial density/temperature distributions and the rotational profiles in the interior of the wobbling HMHS after the collapse generates a high-temperature shell within the hadron-quark mixed phase region of the remnant.

scholarly journals Twin stars: probe of phase transition from hadronic to quark matter

2021 ◽  
Vol 252 ◽  
pp. 06001
Author(s):  
Themistoklis Deloudis ◽  
Polychronis Koliogiannis ◽  
Charalampos Moustakidis
Keyword(s):  
Phase Transition ◽  
Neutron Stars ◽  
Quark Matter ◽  
Compact Stars ◽  
Stable Configuration ◽  
First Order ◽  
Maxwell Construction ◽  
First Order Transition ◽  
Hybrid Stars ◽  
Quark Phase

In agreement with the gravitational-wave events which are constantly increasing, new aspects of the internal structure of compact stars have come to light. A scenario in which a first order transition takes place inside these stars is of particular interest as it can lead, under conditions, to a third gravitationally stable branch (besides white dwarfs and neutron stars). This is known as the twin star scenario. The new branch yields stars with the same mass as normal compact stars but quite different radii. In the current work, we focus on hybrid stars undergone a hadron to quark phase transition near their core and how this new stable configuration arises. Emphasis is to be given especially in the aspects of the phase transition and its parametrization in two different ways, namely with Maxwell construction and with Gibbs construction. Qualitative findings of mass-radius relations of these stars will also be presented.

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 SU(2) Chiral Sigma Model Study of Phase Transition in Hybrid Stars

2003 ◽  
Vol 18 (30) ◽  
pp. 2135-2145 ◽  
Author(s):  
P. K. Jena ◽  
L. P. Singh
Keyword(s):  
Phase Transition ◽  
Neutron Star ◽  
Nuclear Matter ◽  
Quark Matter ◽  
Sigma Model ◽  
Maximum Mass ◽  
Model Study ◽  
Stable Solutions ◽  
Hybrid Stars ◽  
Matter Component

We use a modified SU(2) chiral sigma model to study nuclear matter component and simple bag model for quark matter constituting a neutron star. We also study the phase transition of nuclear matter to quark matter with the mixed phase characterized by two conserved charges in the interior of highly dense neutron stars. Stable solutions of Tolman–Oppenheimer–Volkoff equations representing hybrid stars are obtained with a maximum mass of 1.67M⊙ and radius around 8.9 km.

scholarly journals Hybrid Stars in the Framework of NJL Models

2017 ◽  
Vol 45 ◽  
pp. 1760026 ◽  
Author(s):  
Gustavo A. Contrera ◽  
Milva Orsaria ◽  
I. F. Ranea-Sandoval ◽  
Fridolin Weber
Keyword(s):  
Phase Transition ◽  
Quark Matter ◽  
Mean Field ◽  
Field Approximation ◽  
Hadronic Matter ◽  
High Mass ◽  
Mean Field Approximation ◽  
Soft Phase ◽  
Non Local ◽  
Hybrid Stars

We compute models for the equation of state (EoS) of the matter in the cores of hybrid stars. Hadronic matter is treated in the non-linear relativistic mean-field approximation, and quark matter is modeled by three-flavor local and non-local Nambu−Jona-Lasinio (NJL) models with repulsive vector interactions. The transition from hadronic to quark matter is constructed by considering either a soft phase transition (Gibbs construction) or a sharp phase transition (Maxwell construction). We find that high-mass neutron stars with masses up to [Formula: see text] may contain a mixed phase with hadrons and quarks in their cores, if global charge conservation is imposed via the Gibbs conditions. However, if the Maxwell conditions is considered, the appearance of a pure quark matter core either destabilizes the star immediately (commonly for non-local NJL models) or leads to a very short hybrid star branch in the mass-radius relation (generally for local NJL models).

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 PHASE TRANSITION AND HYBRID STAR IN AN SU(2) CHIRAL SIGMA MODEL

2002 ◽  
Vol 17 (40) ◽  
pp. 2633-2646 ◽  
Author(s):  
P. K. JENA ◽  
L. P. SINGH
Keyword(s):  
Phase Transition ◽  
Nuclear Matter ◽  
Quark Matter ◽  
Sigma Model ◽  
Mean Field ◽  
Maximum Mass ◽  
Hybrid Star ◽  
Field Approach ◽  
Stable Solutions ◽  
Hybrid Stars

We use a modified SU(2) chiral sigma model to study nuclear matter at high density using mean field approach. We also study the phase transition of nuclear matter to quark matter in the interior of highly dense neutron stars. Stable solutions of Tolman–Oppenheimer–Volkoff equations representing hybrid stars are obtained with a maximum mass of 1.69M⊙, radii around 9.3 km and a quark matter core constituting nearly 55–85% of the star radii.

Strange quark mass effect on the structure of hybrid stars

2018 ◽  
Vol 27 (01) ◽  
pp. 1850006 ◽  
Author(s):  
Jian-Feng Xu ◽  
Yan-An Luo ◽  
Lei Li ◽  
Guang-Xiong Peng
Keyword(s):  
Quark Matter ◽  
Quark Mass ◽  
Strange Quark ◽  
Mass Effect ◽  
Compact Stars ◽  
Model Parameters ◽  
Maximum Mass ◽  
Strange Quark Mass ◽  
Wide Range ◽  
Hybrid Stars

We study the strange quark mass effect on the phase diagram of strong interaction and the structure of compact stars with a thermodynamically enhanced perturbative QCD model by matching quark matter onto nuclear matter using the Gibbs conditions. It is found that the mass effect of strange quark matter can obviously stiffen the equation of state of mixed phases and result in more massive hybrid stars (HSs), while that usually lowers the maximum mass of pure quark stars. Given reasonable model parameters, the maximum mass of HSs can reach two times the solar mass and the stars always have mixed-phase core in a considerably wide range of model parameters.

A high-pressure structural study of lawsonite using angle-dispersive powder-diffraction methods with synchrotron radiation

2001 ◽  
Vol 65 (1) ◽  
pp. 41-58 ◽  
Author(s):  
A. R. Pawley ◽  
D. R. Allan
Keyword(s):  
Phase Transition ◽  
Synchrotron Radiation ◽  
Powder Diffraction ◽  
Diamond Anvil Cell ◽  
Phase Region ◽  
Stability Field ◽  
First Order ◽  
The Earth ◽  
Diamond Anvil ◽  
Mixed Phase Region

AbstractStructural refinements of lawsonite have been obtained at pressures up to 16.5 GPa using angle-dispersive powder diffraction with synchrotron radiation on a natural sample contained in a diamond anvil cell. Lawsonite compresses smoothly and relatively isotropically up to 10 GPa. Its bulk modulus is 126.1(6) GPa (for K’ = 4), consistent with previous results. A trend of decreasing Si–O–Si angle indicates that compression is accommodated partly through the narrowing of the cavities containing Ca and H2O in the [001]ortho direction. At 10–11 GPa there is a phase transition from Cmcm to P21/m symmetry. The occurrence of a mixed-phase region, spanning >1 GPa, indicates that the transition is first order in character. The phase transition occurs through a shearing of (010)ortho sheets containing AlO6 octahedral chains in the [100]ortho direction, which causes an increase in βmono. Across the transition, the number of oxygens coordinated to Ca increases from 8 to 9, causing an increase in the average Ca–O bond length. The compressibility of P21/m lawsonite could not be determined due to solidification of the methanol/ethanol pressure-transmitting medium. On the basis of an experiment in which the P21/m lawsonite structure was heated to 200°C at 12.0 GPa, we predict a shallow positive P-T slope for the phase transition, and therefore no stability field for P21/m lawsonite in the Earth.

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