The Structure and the Density of a Bare Quark Star in a Cold Genesis Theory of Particles

Based on the preonic structure of quarks obtained in a Cold genesis theory of particles (CGT), it was obtained a semi-empiric relation for the current mass of quarks specific to CGT but with the constants obtained with the aid of the Gell-Mann-Oakes-Renner formula, giving values close to those obtained by the Standard Model, the current quark’s volume at ordinary nuclear temperature being obtained as sum of theoretic apparent volumes of preonic kerneloids. The maximal densities of the current quarks: strange (s), charm (c), bottom (b), and top (t) resulted in the range (0.8 - 4.2) × 1018 kg/m3, as values which could be specific to possible quark stars, in concordance with previous results. By the preonic quark model of CGT, the possible structure of a quark star resulted from the intermediary transforming: Ne(2d+u)→s−¯+λ−and the forming of composite quarks with the structure: C−(λ−-s−¯-λ−) and C+(s−¯-λ−-s−¯), and of Sq-layers: C+C−C+ and C−C+C− which can form composite quarks: Hq±=(SqS¯qSq);(S¯qSqS¯q), corresponding to a constituent mass: M(Hq) = (12,642;12,711) MeV/c2, the forming of heavier quarks inside a quark star resulting as possible in the form: Dq = n3Cq, (n ≥ 3). The Tolman-Oppenheimer limit: MT=0.7M⊙for neutron stars can also be explained by the CGT’s quark model.

Gravitational wave echoes from strange quark stars in the equation of state with density-dependent quark masses

According to the recent studies,the gravitational wave(GW)echoes are expected to be generated by quark stars composed of ultrastiff quark matter.The ultrastiff equations of state(EOS)for quark matter were usually obtained either by a simple bag model with artificially assigned sound velocity or by employing interacting strange quark matter(SQM)depicted by simple reparameterization and rescaling.In this study,we investigate GW echoes with EOSs for SQM in the framework of the equivparticle model with density-dependent quark masses and pairing effects.We conclude that strange quark stars(SQSs)can be sufficiently compact to possess a photon sphere capable of generating GW echoes with frequencies in the range of approximately 20 kHz.However,SQSs cannot account for the observed 72 Hz signal in GW170817 event.Furthermore,we determined that quark-pairing effects play a crucial role in enabling SQSs to satisfy the necessary conditions for producing these types of echoes.

A Gaussian Model for Anisotropic Strange Quark Stars

For studying the anisotropie strange quark stars, we assume that the radial pressure inside an anisotropic star can be obtained simply by isotropie pressure plus an additional Gaussian term with three free parameters （A, μ and X）. According to recent observations, a pulsar in a mass range of 1.97±0.04M has been measured. Hence, we take this opportunity to set the free parameters of our model. We fix X by applying boundary and stability conditions and then search the A - μ parameter space For a maximum mass range of 1.9M 〈 Mmax 〈 2.1M. Our results indicate that anisotropy increases the maximum mass M and also its corresponding radius R for a typical strange quark star. Furthermore, our model shows magnetic field and electric charge increase the anisotropy factor △. In fact, △ has a maximum on the surface and this maximum goes up in the presence of magnetic field and electric charge. Finally, we show that anisotropy can be more effective than either magnetic field or electric charge in raising maximum mass of strange quark stars.

Geddanken Experiment for Quark Star Idea, Quantum Wavelength Limit, Minimum Time, and Early Universe Temperature, from First Principles

We initially look at a non singular universe representation as given by Rovelli and Vidotto, in terms of a quantum bounce, via minimum mass quark stars, as a start of how to estimate of entropy and also of the number of operations of an expanding universe. The bench mark used is, to after considering a quark star, to look at the mass of a universe, estimated, and from there, we can obtain the entropy if we look at the Schwartzshield radii of a universe, and then the radii of the universe about 380,000 years after the big bang. In the latter, we show how to get the number of operations as akin to the reasoning used by Seth Lloyd, in 2001, and also from there close with a few comments as to the “naturalness” of heavy Gravity from this formulation of entropy, which is based upon a start of considering what is a Planck star, as far as minimum quantum effects in Black hole physics, and by extension early universe cosmology.

Looking at the Physics of What a Quark Star-Black Hole Binary Would Create in Terms of GW Signals and New Physics

A quark star, black hole pairing as a would-be Gravitational wave generator is brought up. Quark stars are, anyway, likely to be black holes, above a certain mass limit, whereas a quark star in itself obey thermodynamic “laws” which in certain ways differ from the traditional black hole models. We list some of the probable consequences of such a binary, and make predictions as to certain GW phenomenon which will have observational consequences. i.e., a GW “change in energy” from a black hole—Quark star pair would likely be within 90% of that of comparatively massed black hole—black hole binary pair. The electromagnetic “profile” of the two cases would differ dramatically, and we conclude our inquiry with an open question if a generalized uncertainty principle could play a role in comparing the 7th and 8th equations of our presentation.

An Exact Anisotropic Quark Star Model

We present an exact analytical solution of the gravitational field equations describing a static spherically symmetric anisotropic quark matter distribution. The radial pressure inside the star is assumed to obey a linear equation of state, while the tangential pressure is a complicated function of the radial coordinate. In order to obtain the general solution of the field equations a particular density profile inside the star is also assumed. The anisotropic pressure distribution leads to an increase in the maximum radius and mass of the quark star, which in the present model is around three solar masses.

A new parametric equation of state and quark stars

It is still a matter of debate to understand the equation of state of cold matter with supra-nuclear density in compact stars because of unknown non-perturbative strong interaction between quarks. Nevertheless, it is speculated from an astrophysical view point that quark clusters could form in cold quark matter due to strong coupling at realistic baryon densities. Although it is hard to calculate this conjectured matter from first principles, one can expect that the inter-cluster interaction will share some general features with the nucleon- nucleon interaction successfully depicted by various models. We adopt a two-Gaussian component soft-core potential with these general features and show that quark clusters can form stable simple cubic crystal structure if we assume that the wave function of quark clusters have a Gaussian form. With this parametrization, the Tolman-Oppenheimer-Volkoff equation is solved with reasonably constrained parameter space to give massradius relations of crystalline solid quark stars. With baryon number densities truncated at 2n0 at surface and the range of the interaction fixed at 2 fm we can reproduce similar mass-radius relations to that obtained with bag model equations of state. The maximum mass ranges from - 0.5M⊙ to 〉 ～ 3M⊙. The recently measured high pulsar mass （〉～ 2M⊙） is then used to constrain the parameters of this simple interaction potential.

Stability of Quark Star Models

In this paper,we investigate the stability of quark stars with four different types of inner matter configurations;isotropic,charged isotropic,anisotropic and charged anisotropic by using the concept of cracking.For this purpose,we have applied local density perturbations technique to the hydrostatic equilibrium equation as well as on physical parameters involved in the model.We conclude that quark stars become potentially unstable when inner matter configuration is changed and electromagnetic field is applied.

Influence of a scalar-isovector δ-meson field on the quark phase structure in neutron stars

The deconfinement phase transition from hadronic matter to quark matter in the interior of compact stars is investigated. The hadronic phase is described in the framework of relativistic mean-field theory, where the scalar-isovector 6-meson effec- tive field is also taken into account. The MIT bag model for describing a quark phase is used. The changes of the parameters of phase transition caused by the presence of a δ-meson field are explored. Finally, alterations in the integral and structural parameters of hybrid stars due to both a deconfinement phase transition and inclusion of a δ-meson field are discussed.

Calculations for Density of Quark Core Consisting of Mono Flavored Closely Packed Quarks inside Neutron Star

The attempt has been taken to calculate the density of stars possessing quark matter core using sphere packing concept of crystallography. The quark matter has been taken as solid in nature as predicted in references 36 and 37, and due to immense gravitational pressure at the core of the star the densest packing of quarks as spheres has been assumed to calculate the packing fraction Φ, thus the density ρ of the matter. Three possible types of pickings—mono-sized sphere packing, binary sphere packing and ternary sphere packing, have been worked out using three possible types of quark matter. It has been concluded that no value about the ρ of quark matter can be calculated using binary and ternary packing conditions and for mono-sized packing condition different flavor quark matters of different values in the density have been calculated using results from the experiments done by HI, ZEUS, L3 and CDF Collaborations about the radius limit of quark. For example, for u quark matter ρ ranges from 4.0587 × 1048 - 7.40038 × 1048 MeV/c2 cm3 using results of L3 Collaboration, for s quark matter 15.91794 × 1048 - 17.6866 × 1048 MeV/c2 cm3, etc.

色味锁夸克物质与夸克星

讨论了零温、强磁场下基于准粒子模型的奇异夸克物质、色味锁夸克物质的热力学性质.结果表明色味锁夸克物质比奇异夸克物质更稳定,压强会随着色味锁态能隙常数的增大而增加.并且发现强磁场下磁星的最大质量会随着色味锁夸克物质的能隙常数的增加而增加,磁星的潮汐形变率会随着能隙常数的增加而增加,磁星最大质量的中心密度会随着能隙常数的增加而降低.结果还说明考虑色味锁态得到的磁星质量半径关系可以满足最近实验观测PSR J0740+6620,PSR J0030+0451,和HESS J1731-347所给出的质量半径约束.

Isoscalar-vector interaction and its influence on the hadron-quark phase transition

The hadron-quark phase transition is studied with the newly constructed Hadron-Poyakov-Nambu- Jona-Lasinio(PNJL) model.Particularly,in the description of quark matter,we include the isoscalar-vector interaction.With the constraints of neutron star observations,our calculation shows the isoscalar-vector interaction between quarks is indispensable if massive hybrids star exist in the universe.Its strength determines the onset density of quark matter,and the mass-radius relations of hybrid stars.Also,as a connection with heavy-ion-collision experiments,we discuss the strength of isoscalar-vector interaction and its effect on the signals of hadron-quark phase transition in heavy-ion collisions,such as NICA at JINR-Dubna and FAIR at GSI-Darmstadt.

A quark nova in the wake of a core-collapse supernova:a unifying model for long duration gamma-ray bursts and fast radio bursts

By appealing to a quark nova(QN;the explosive transition of a neutron star to a quark star) in the wake of a core-collapse supernova(CCSN) explosion of a massive star,we develop a unified model for long duration gamma-ray bursts(LGRBs) and fast radio bursts(FRBs).The time delay(years to decades)between the SN and the QN,and the fragmented nature(i.e.,millions of chunks) of the relativistic QN ejecta are key to yielding a robust LGRB engine.In our model,an LGRB light curve exhibits the interaction of the fragmented QN ejecta with turbulent(i.e.,filamentary and magnetically saturated) SN ejecta which is shaped by its interaction with an underlying pulsar wind nebula(PWN).The afterglow is due to the interaction of the QN chunks,exiting the SN ejecta,with the surrounding medium.Our model can fit BAT/XRT prompt and afterglow light curves simultaneously with their spectra,thus yielding the observed properties of LGRBs(e.g.,the Band function and the X-ray flares).We find that the peak luminositypeak photon energy relationship(i.e.,the Yonetoku law),and the isotropic energy-peak photon energy relationship(i.e.,the Amati law) are not fundamental but phenomenological.FRB-like emission in our model results from coherent synchrotron emission(CSE) when the QN chunks interact with non-turbulent weakly magnetized PWN-SN ejecta,where conditions are prone to the Weibel instability.Magnetic field amplification induced by the Weibel instability in the shocked chunk frame sets the bunching length for electrons and pairs to radiate coherently.The resulting emission frequency,luminosity and duration in our model are consistent with FRB data.We find a natural unification of high-energy burst phenomena from FRBs(i.e.,those connected to CCSNe) to LGRBs including X-ray flashes(XRFs) and X-ray rich GRBs(XRR-GRBs) as well as superluminous SNe(SLSNe).We find a possible connection between ultra-high energy cosmic rays and FRBs and propose that a QN following a binary neutron star merger can yield a short duration GRB(SGRB) with fits to BAT/XRT light curves.

Effects of non-Newtonian gravity on the properties of strange stars

The properties of strange star matter are studied in the equivparticle model with inclusion of non-Newtonian gravity. It is found that the inclusion of non-Newtonian gravity makes the equation of state stiffer if Witten＇s conjecture is true. Correspondingly, the maximum mass of strange stars becomes as large as two times the solar mass, and the maximum radius also becomes bigger. The coupling to boson mass ratio has been constrained within the stability range of strange quark matter.

Scalar-isovector δ-meson mean-field and mixed phase structure in compact stars

The deconfinement phase transition from ha-dronic matter to quark matter in the interior of compact stars is investigated. The hadronic phase is described in the framework of relativistic mean-field (RMF) theory, when also the scalar-isovector δ-meson effective field is taken into account. The MIT bag model for describing a quark phase is used. The changes of the pa-rameters of phase transition caused by the pre- sence of δ-meson field are investigated. Finally, alterations in the integral and structure para-meters of hybrid stars due to deconfinement phase transitions are discussed.

The Remnant of GW170817: A Trapped Neutron Star with a Massive Incompressible Superfluid Core

Our bimetric spacetime model of glitching pulsars is applied to the remnant of GW170817. Accordingly, pulsars are born with embryonic incompressible superconducting gluon-quark superfluid cores (SuSu-matter) that are embedded in Minkowski spacetime, whereas the ambient compressible and dissipative media (CDM) are imbedded in curved spacetime. As pulsars cool down, the equilibrium between both spacetime is altered, thereby triggering the well-observed glitch phenomena. Based thereon and assuming all neutron stars (NSs) to be born with the same initial mass of , we argue that the remnant of GW170817 should be a relatively faint NS with a massive central core made of SuSu-matter. The effective mass and radius of the remnant are predicted to be and Rrem=10.764 Km, whereas the mass of the enclosed SuSu-core is . Here, about 1/2Mcore is an energy enhancement triggered by the phase transition of the gluon-quark-plasma from the microscopic into macroscopic scale. The current compactness of the remnant is , but predicted to increase as the CDM and cools down, rendering the remnant an invisible dark energy object, and therefore to an excellent black hole candidate.

轻夸克物质团、奇异子和致密矮星

相对于核物质和奇异夸克物质,仅由两味夸克构成的轻夸克物质(即ud夸克物质)有可能更稳定.而对于由这三类物质构成的典型物质集团,研究发现如果ud夸克物质具有较大的对称能,那么其物质团会在特定大小(重子数A≈1000)时最稳定.在这种情况下,就可能存在由ud夸克物质团和电子构成的致密矮星,即ud夸克矮星.通过进一步研究这类ud夸克矮星的结构可知:相较于传统的由原子核和电子构成的白矮星,ud夸克矮星通常具有较小的半径,而被正常物质覆盖的ud夸克矮星的半径则在它们之间,这与最近观测到的质量和半径都异常小的白矮星相符.

Cosmic Applications of Relative Energy between Quarks in Nucleons

By taking into account the relative energy between the diquark and the quark in nucleons, the gravitational singularity in a black hole created from a collapsing neutron star can be removed;compatibility with quantum mechanics is restored. This black hole becomes a “black” neutron star. The negative relative energy identified as dark matter in the previous paper can account for the galaxy rotation curve. The positive relative energy identified as dark energy in the previous paper can explain the accelerating expansion of the universe. A possible scenario for cosmic ray generation is given.

夸克物质与夸克星

二十世纪六七十年代强子结构研究的进展使人们认识到了亚核子——夸克——的存在。随后,实验和理论上关于夸克之间作用渐近自由性质的发现使学者们明确地提出了"夸克物质"的概念。理论上预言的这种物质是否真的存在将在很大程度上检验目前基本强作用的理论。夸克星就是夸克物质的可能存在形式之一,相关研究也是人们探索超核密度物质状态的重要途径。该文简述脉冲星、中子星及夸克星的研究历史,总结了近年来夸克物质与夸克星研究的重要成果,指出了夸克星与一般中子星的异同以及若干夸克星候选体。

脉冲星与夸克星

简要地回顾了脉冲星、中子星和夸克星的研究历史;总结了当前(特别是笔者所在研究小组)对于夸克星研究的进展并指出所面临的主要问题,特别讨论了区分普通中子星和夸克星的可能途径;给出了一些夸克星候选体以及未来可能的观测检验。