We investigate the possible existence of anomalous mass defects in the low mass region of stellar sequences of strange stars.
We employ the nonperturbative equation of state derived in the framework of the Field Correlator Method to describe the hydrostatic equilibrium of the strange matter.
The large distance static $Q{\bar Q}$ potential $V_1$ and the gluon condensate $G_2$ are the main parameters of the model.
We use the surface gravitational redshift measurements as a probe to determine the ratio $({\cal P}/{\cal E})_C$ at the center of strange stars.
For $V_1=0$ and $G_2\gappr0.035\,{\rm GeV}^4$\,, we show that $({\cal P}/{\cal E})_C\simeq0.262$ and the corresponding redshift $z_S\simeq0.47$ are limiting values, at the maximum mass of the highest mass stellar sequence.
As a direct application of our study, we try to determine the values of $V_1$ and $G_2$ from astrophysical observations of the compact star 1E\,1207.4-5209. Due to the uncertainties in the surface redshift determination, we made two attempts to obtain the model parameters.
Our findings show that $({\cal P}/{\cal E})_C=0.073^{+0.029}_{+0.024}$\, at 68\% confidence, $V_1=0.44\pm0.10$\,GeV at 90\% confidence and $G_2=0.008\pm0.001\,{\rm GeV}^4$ at 95\% confidence \, in the first attempt; and $({\cal P}/{\cal E})_C=0.073^{+0.029}_{+0.024}=0.087\pm0.028$\, at 71\% confidence, $V_1=0.43\pm0.085$\,GeV at 94\% confidence and $G_2=0.0093\pm0.00092\,{\rm GeV}^4$ at 94\% confidence in the second attempt.
These values of $V_1$ and $G_2$ are in reasonable agreement with the lattice and QCD sum rules calculations.
As a consequence of the high values of $V_1$ and $G_2$, the anomalous mass defects of 1E\,1207.4-5209 are $|Δ_2M|\simeq2.56\times10^{53}$\,erg\, in the first attempt and $|Δ_2M|\simeq2.94\times10^{53}$\,erg\, in the second attempt.
We study the partial fragmentation of a strange quark star into strangelets during the process of merger of two strange quark stars. We discuss the fate of the fragments considering their possible evaporation into nucleons. We show that only a rather small amount of large size strangelets, ejected from the spiral arms in the post-merger, survives a total evaporation into nucleons. In this way we demonstrate that: 1) the density of strangelets in the galaxy is too low to trigger the conversion of all neutron stars into strange quark stars and it allows the co-existence of both types of compact …
Definitely, an affirmative answer to this question would have implications of fundamental importance for astrophysics (a new class of compact stars), and for the physics of strong interactions (deconfined phase of quark matter, and strange matter hypothesis). In the present work, we use observational data for the newly discovered millisecond X-ray pulsar SAX J1808.4-3658 and for the atoll source 4U 1728-34 to constrain the radius of the underlying compact stars. Comparing the mass-radius relation of these two compact stars with theoretical models for both neutron stars and strange stars, we ar…
Droplets of absolutely stable strange quark matter (strangelets) immersed in a lepton background may be the energetically preferred composition of strange star crusts and of the interior of a new class of stars known as strangelet dwarfs. In this work we calculate the surface tension $σ$ and the curvature coefficient $γ$ of charged strangelets as a function of the baryon number density, the temperature, the chemical potential of trapped neutrinos, the strangelet size, the electric potential and the electric charge at their boundary. Strange quark matter in chemical equilibrium and with global …
We explore the effects of strangeness and $Δ$ resonance in baryonic matter and compact stars within the relativistic-mean-field (RMF) models. The covariant density functional PKDD is adopted for $N$-$N$ interaction, parameters fixed based on finite hypernuclei and neutron stars are taken for the hyperon-meson couplings, and the universal baryon-meson coupling scheme is adopted for the $Δ$-meson couplings. In light of the recent observations of GW170817 with the dimensionless combined tidal deformability $197 \leq \barΛ\leq 720$, we find it is essential to include the $Δ$ resonances in compact …
We investigate the thermodynamic properties of strange quark matter under the strong magnetic field in the framework of the MIT bag model in two cases of bag constants. We consider two cases of the magnetic field, the uniform magnetic field and the density-dependent magnetic field to calculate the equation of state of strange quark matter. For the case of density-dependent magnetic field, we use a Gaussian equation with two free parameters $β$ and $θ$ and use two different sets of the parameters for the magnetic field changes (a slow and a fast decrease of the magnetic field from the center to…
In this contribution we review the dynamics of hyperons with nucleons and nuclear matter, paying a special attention to hypernuclei. We also discuss the presence of hyperons in the inner core of neutron stars and the consequences for the structure of these compact stars.
