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Quark-cluster Stars: the structure
The nature of pulsar-like compact stars is still in controversy although the
first pulsar was found more than 40 years ago. Generally speaking, conventional
neutron stars and non-mainstream quark stars are two types of models to
describe the inner structure of pulsars, with the former composed mainly of
hadrons and the latter of a peculiar kind of matter whose state equation should
be understood in the level of quarks rather than hadrons. To construct a more
realistic model from both theoretical and observational points of view, we
conjecture that pulsars could be "quark-cluster stars" which are composed of
quark-clusters with almost equal numbers of up, down and strange quarks.
Clustering quark matter could be the result of strong coupling between quarks
inside realistic compact stars. The lightest quark clusters could be of
H-dibaryons, while quark clusters could also be heavier with more quarks. Being
essentially related to the non-perturbative quantum-chromo dynamics (QCD), the
state of supra-nuclear condensed matter is really difficult to obtain strictly
by only theoretical QCD-calculations, and we expect, nevertheless, that
astrophysical observations could help us to have a final solution.Comment: 10 pages, 2 figures, talk at the 3rd Galileo-XuGuangqi Meeting (11-15
October 2011, Beijing
Strangeons constitute bulk strong matter-- To test using GW170817
The fundamental strong interaction determines the nature of pulsar-like
compact stars which are essentially in the form of bulk strong matter. From an
observational point of view, it is proposed that bulk strong matter could be
composed of strangeons, i.e. quark-clusters with there-light-flavor symmetry of
quarks, and therefore pulsar-like compact objects could actually be strangeon
stars. The equation of state (EOS) of strangeon stars is described in a
Lennard-Jones model for the purpose of constraining the EOS by both the tidal
deformability of GW170817 and . It is found that the
allowed parameter space is quite large as most of the Lennard-Jones EOS models
satisfy the tidal deformability constraint by GW170817. The future GW
detections for smaller values of and mass measurement for larger
values of will help a better constraint on the strangeon star
model.Comment: Accepted by the EPJA Topical Issue "The first Neutron Star Merger
Observation - Implications for Nuclear Physics
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