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Ryszard Manka

Publications and source records attributed to Ryszard Manka.

14 recordsLinked to original sources
arXiv2013

The influence of the enhanced vector meson sector on the properties of the matter of neutron stars

This paper gives an overview of the model of a neutron star with non-zero strangeness constructed within the framework of the nonlinear realization of the chiral $SU(3)_{L}\times SU(3)_{R}$ symmetry. The emphasis is put on the physical properties of the matter of a neutron star. The obtained solution is particularly aimed at the problem of the construction of a theoretical model of a neutron star matter with hyperons that will give high value of the maximum mass.

astro-ph.SR↗
arXiv2009

Role of nonlinear vector meson interactions in hyperon stars

The extended nonlinear model has been applied to construct neutron star matter equation of state. In the case of neutron star matter with non-zero strangeness the extension of the vector meson sector by the inclusion of nonlinear mixed terms results in the stiffening of the equation of state and accordingly in the higher value of the maximum neutron star mass.

nucl-th↗
arXiv2006

The hyperon neutron star mean field model

In this paper the impact of the strength of hyperon-nucleon and hyperon-hyperon on the maximum neutron star mass is shown. The strong hyperon-hyperon coupling constant together with the additional nonlinear meson interaction terms lead to the essential softening of the equation of state and to the existence of another more compact branch of stable neutron star configurations. The analysis of the mass-radius relations leads to the conclusion that the additional stable configurations of hyperon-rich neutron stars are characterized by the reduced value of radii.

nucl-th↗
arXiv2006

Properties of a protoneutron star in the Effective Field Theory

The complete form of the equation of state of strangeness rich proto-neutron and neutron star matter has been obtained. The currently obtained lower value of the Lambda Lambda potential at the level of 5 MeV permits the existence of additional parameter set which reproduces the weaker Lambda Lambda interaction. The effects of the strength of hyperon-hyperon interactions on the equations of state constructed for the chosen parameter set have been analyzed. It has been shown that replacing the strong Y-Y interaction model by the weak one introduces large differences in the composition of a proto-neutron star matter both in the strange and non-strange sectors. Also concentrations of neutrinos have been significantly altered in proto-neutron star interiors. The performed calculations have indicated that the change of the hyperon-hyperon coupling constants affects the value of the proto-neutron star maximum mass.

nucl-th↗
arXiv2004

The compact star in the SU(3) sigma model

The linear chiral SU(3)*SU(3) model is applied to describe properties of the compact star matter inside the quark, protoneutron and neutron star.The leads to the neutron star with the value of maximum mass close to 1.5 solar mass and radius 11 km and with the reduced value of proton fraction and very compact hyperon core.

nucl-th↗
arXiv2004

Properties and evolution of a protoneutron star in the enlarged SU(3) model

Protoneutron stars are hot and lepton rich objects formed as a result of type II supernovae explosion. This paper describes results of analysis of protoneutron star models constructed under the assumptions that strange particles are present in the core. All calculations have been performed for the neutrino opaque matter when the entropy per baryon is of the order 2. The equation of state which is crucial for the structure and composition of a star has been obtained in the framework of the chiral SU(3) model and compared with the one involving derivative coupling of baryons to mesons. Of special interest in this paper is the comparison of the two protoneutron star models with those formed when neutrinos leak out of the system, described as cool, deleptonized neutron stars. It has been shown that the maximum mass of the hot protoneutron star with trapped neutrinos is close to 1.9 M (the Sun Mass) in case of the SU(3) model. However, deleptonization reduces the value of stable protoneutron star mass significantly to 1.5 M.

nucl-th↗
arXiv2001

The nucleon and mesons effective masses in the Relativistic Mean-Field Theory

Nucleon and meson effective masses in the nonlinear Relativistic Mean - Field Theory (RMF) introducing a nonlinear omega - rho and sigma coupling motivated by the Quark Meson Coupling model (QMC) is explored. It is shown that, in contrast to the usual Walecka model, not only the effective nucleon mass m_{eff,N} but also the effective sigma, rho meson masses (m_{eff, sigma}, m_{eff, rho}) and the effective omega meson mass m_{eff, omega} are nucleon density dependent.

nucl-th↗
arXiv2000

Structure and properties of neutron stars in the Relativistic Mean - Field Theory

Properties of rotating neutron stars with the use of relativistic mean-field theory are considered. The performed analysis of neutron star matter is based on the nonlinear Lgrangian density. The presence of nonlinear interaction of vector mesons modifies the density dependence of the rho field and influences bulk parameters of neutron stars. The observed quasi-periodic X-ray oscillations of low mass X-ray binaries can be used in order to constrain the equation of state of neutron star matter. Having assumed that the maximum frequency of the quasi periodic oscillations originates at the circular orbit it is possible to estimate masses and radii of neutron stars.

nucl-th↗
arXiv2000

The neutron star in the Relativistic Mean-Field Theory

The nucleon effective mass, binding energy and neutron star configuration in the Relativistic Mean-Field Theory (RMF) is considered. The calculation are motivated by the construction of the equation of state for a neutron star in the RMF. The equation of state for the parameters set TM1 is calculated using the Feynman - Bogolubov variational method for temperature different from zero. The structure of the neutron star is presented. The maximal stable configuration are obtained for: M_max=1.91 M_Sun and R=12.84 km.

nucl-th↗
arXiv1999

The hot neutron star

In this paper the equation of state of hot neutron matter is calculated. Involving the Oppenheimer-Volkov-Tolman equation global parameters of a neutron star at the finite temperature are obtained. The objective of our work was to study the influence of the temperature on the main parameters of a neutron star.

nucl-th↗
arXiv1996

The soliton stars evolution

The evolution of a soliton star filled with fermions is studied in the framework of general relativity. Such a system can be described by the surface tension $σ$, the bag constant $B$, and the fermion number density $ρ_{0}$. Usually one of these parameters prevails in the system and thus affects the spacetime inside the soliton. Whether it is described by Friedman or de Sitter metric depends on the prevailing parameter. The whole spacetime is devided by the surface of the soliton into the false vacuum region inside the soliton and the true vacuum region outside, the latter being described by the Schwarzschild line element. The aim of this paper is to study the equations of motion of the domain wall in two cases. In the first case the de Sitter metric describes the interior in the first case, and in the second case it is replaced by the Friedman metric. In both of them the Schwarzschild metric is outside the soliton. From the analysis of obtained equations one can draw conclusions concerning further evolution of a soliton star.

astro-ph↗
arXiv1996

QCD deconfinement -- phase transitions and collapsing quark stars

In this paper we discuss the QCD phase-transitions in the nontopological soliton model of quark confinement and explore possible astrophysical consequences. Our key idea is to look at quark stars (which are believed to exist since the quark matter is energetically preferred over the ordinary matter) from the point of view of soliton model. We propose that the phase transition taking place during the core collapse of massive evolved star may provide a new physical effect not taken into account in modeling the supernova explosions. We also point out the possibility that merging quark stars may produce gamma-ray bursts energetic enough to be at cosmological distances. Our idea based on the finite-temperature nontopologiocal soliton model overcomes major difficulties present in neutron star merger scenario --- the baryon loading problem and nonthermal spectra of the bursts.

astro-ph↗