scholarly journals QUARK-CLUSTER STARS: HINTS FROM THE SURFACE

2012 ◽  
Vol 10 ◽  
pp. 137-146
Author(s):  
SHI DAI ◽  
RENXIN XU
Keyword(s):  
Dense Matter ◽  
Compact Stars ◽  
Cluster Star ◽  
Cluster Phase ◽  
Vacuum Gaps ◽  
Cold Dense Matter ◽  
Star Surface ◽  
Absorption Features ◽  
Bare Surface ◽  
Contamination Problem

The matter inside pulsar-like compact stars could be in a quark-cluster phase since in cold dense matter at a few nuclear densities (ρ ~ 2 - 10ρ0), quarks could be coupled still very strongly and condensate in position space to form quark clusters. Quark-cluster stars are chromatically confined and could initially be bare, therefore the surface properties of quark-cluster stars would be quite different from that of conventional neutron stars. Some facts indicate that a bare and self-confined surface of pulsar-like compact stars might be necessary in order to naturally understand different observational manifestations. On one hand, as for explaining the drifting sub-pulse phenomena, the binding energy of particles on pulsar surface should be high enough to produce vacuum gaps, which indicates that pulsar's surface might be strongly self-confined. On the other hand, a bare surface of quark-cluster star can overcome the baryon contamination problem of γ-ray burst as well as promote a successful core-collapse supernova. What is more, the non-atomic thermal spectra of dead pulsars may indicate also a bare surface without atmosphere, and the hydro-cyclotron oscillation of the electron sea above the quark-cluster star surface could be responsible for those absorption features detected. These hints could reflect the property of compact star's surface and possibly the state of condensed matter inside, and then might finally result in identifying quark-cluster stars.

scholarly journals H-cluster stars

2012 ◽  
Vol 8 (S291) ◽  
pp. 435-437
Author(s):  
X. Y. Lai ◽  
R. X. Xu
Keyword(s):  
Low Temperature ◽  
Experimental Evidence ◽  
Lattice Qcd ◽  
Dense Matter ◽  
Experimental Tests ◽  
Degree Of Freedom ◽  
Compact Stars ◽  
Maximum Mass ◽  
Cold Dense Matter ◽  
Stiffening Effect

AbstractThe study of dense matter at ultra-high density has a very long history, which is meaningful for us to understand not only cosmic events in extreme circumstances but also fundamental laws of physics. In compact stars at only a few nuclear densities but low temperature, quarks could be interacting strongly with each other. That might produce quarks grouped in clusters, although the hypothetical quark-clusters in cold dense matter have not been confirmed due to the lack of both theoretical and experimental evidence. A so-called H-cluster matter is proposed in this paper as the nature of dense matter in reality.Motivated by recent lattice QCD simulations of the H-dibaryons (with structure uuddss), we are therefore considering here a possible kind of quark-clusters, H-clusters, that could emerge inside compact stars during their initial cooling, as the dominant components inside (the degree of freedom could then be H-clusters there). We study the stars composed of H-clusters, i.e., H-cluster stars, and derive the dependence of their maximum mass on the in-medium stiffening effect, showing that the maximum mass could be well above 2 M⊙ as observed and that the resultant mass-radius relation fits the measurement of the rapid burster under reasonable parameters. Besides a general understanding of different manifestations of compact stars, we expect further observational and experimental tests for the H-cluster stars in the future.

scholarly journals Confronting GW190814 with hyperonization in dense matter and hypernuclear compact stars

2020 ◽  
Vol 102 (4) ◽  
Author(s):  
Armen Sedrakian ◽  
Fridolin Weber ◽  
Jia Jie Li
Keyword(s):  
Dense Matter ◽  
Compact Stars

scholarly journals Equation of state constraints for the cold dense matter inside neutron stars using the cooling tail method

2016 ◽  
Vol 591 ◽  
pp. A25 ◽  
Author(s):  
J. Nättilä ◽  
A. W. Steiner ◽  
J. J. E. Kajava ◽  
V. F. Suleimanov ◽  
J. Poutanen
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
State Constraints ◽  
Dense Matter ◽  
Cold Dense Matter

scholarly journals COMPACT STARS IN HADRON AND QUARK-HADRON MODELS

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1455-1462 ◽  
Author(s):  
S. SCHRAMM ◽  
V. A. DEXHEIMER
Keyword(s):  
Phase Diagram ◽  
Neutron Star ◽  
Chiral Symmetry ◽  
Degrees Of Freedom ◽  
Dense Matter ◽  
Compact Stars ◽  
Chiral Symmetry Restoration ◽  
Hybrid Star ◽  
Nonlinear Realization ◽  
Model Approach

We investigate strongly interacting dense matter and neutron stars using a flavor-SU(3) approach based on a nonlinear realization of chiral symmetry. We study chiral symmetry restoration and the equation of state of stellar matter and determine neutron star properties using different sets of degrees of freedom. Finally, we include quarks in the model approach. We show the resulting phase diagram as well as hybrid star solutions for this model.

scholarly journals Strange matter in compact stars

2018 ◽  
Vol 171 ◽  
pp. 08001 ◽  
Author(s):  
Thomas Klähn ◽  
David B. Blaschke
Keyword(s):  
Quark Matter ◽  
Strange Quark ◽  
Chiral Symmetry Breaking ◽  
Dense Matter ◽  
Strange Quark Matter ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Model Description ◽  
Severe Problem ◽  
Strange Matter

We discuss possible scenarios for the existence of strange matter in compact stars. The appearance of hyperons leads to a hyperon puzzle in ab-initio approaches based on effective baryon-baryon potentials but is not a severe problem in relativistic mean field models. In general, the puzzle can be resolved in a natural way if hadronic matter gets stiffened at supersaturation densities, an effect based on the quark Pauli quenching between hadrons. We explain the conflict between the necessity to implement dynamical chiral symmetry breaking into a model description and the conditions for the appearance of absolutely stable strange quark matter that require both, approximately masslessness of quarks and a mechanism of confinement. The role of strangeness in compact stars (hadronic or quark matter realizations) remains unsettled. It is not excluded that strangeness plays no role in compact stars at all. To answer the question whether the case of absolutely stable strange quark matter can be excluded on theoretical grounds requires an understanding of dense matter that we have not yet reached.

scholarly journals Symmetry energy in cold dense matter

2016 ◽  
Vol 945 ◽  
pp. 21-41 ◽  
Author(s):  
Kie Sang Jeong ◽  
Su Houng Lee
Keyword(s):  
Symmetry Energy ◽  
Dense Matter ◽  
Cold Dense Matter

An Equation of State of Cold Dense Matter

1975 ◽  
Vol 53 (3) ◽  
pp. 891-893 ◽  
Author(s):  
A. Nishimura ◽  
Y. Yamaguchi
Keyword(s):  
Equation Of State ◽  
Dense Matter ◽  
Cold Dense Matter

EXPERIMENTAL STUDIES OF ANTIKAON MEDIATED BOUND NUCLEAR SYSTEMS

2007 ◽  
Vol 16 (03) ◽  
pp. 905-918 ◽  
Author(s):  
PAUL KIENLE
Keyword(s):  
Phase Transitions ◽  
Experimental Studies ◽  
Dense Matter ◽  
Nucleon Interaction ◽  
Decay Modes ◽  
Density Distributions ◽  
Nuclear Systems ◽  
Nuclear Clusters ◽  
Experimental Approaches ◽  
Cold Dense Matter

Recent experimental studies of the synthesis and properties of deeply bound antikaon mediated nuclear systems are reviewed. Following a brief introduction in the basic properties of the antikaon–nucleon interaction which may lead to cold and dense antikaonic nuclear systems, we review the results of very first experiments which give indications of the existence of such exotic clusters of matter. Then ongoing efforts to substantiate the early findings are presented and future experimental approaches which will allow a very detailed study of the decay modes, the sizes and density distributions of these kaonic nuclear clusters are discussed including their relevance for possible phase transitions in cold dense matter.

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