We have investigated the crustal properties of neutron stars without fallback accretion. We have calculated the chemical evolution of the neutron star crust in three different cases (a modified Urca process without the thermal influence of a crust, a thick crust, and a direct Urca process with a thin crust) in order to determine the detailed composition of the envelope and atmosphere as the nuc...

We used a newtonian SPH (smooth-particle hydrodynamics) code to follow the final stages of evolution of a coalescing binary system of a neutron star and a black hole. We find that the outcome of the “merger” is very sensitive to the equation of state describing the neutron star. A neutron star with a soft equation of state (polytrope with index Γ = 5/3) is completely disrupted, and a fairly lar...

Neutron star matter is investigated in a hadronic chiral model approach using the lowest flavor-SU(3) multiplets for baryons and mesons. The parameters are determined to yield consistent results for saturated nuclear matter as well as for finite nuclei. The influence of baryonic resonances is discussed. The global properties of a neutron star such as its mass and radius are determined. Proto-ne...

Various models for electromagnetic emissions correlated with the gravitational wave signals expected to be detectable by the current and planned gravitational wave detectors are studied. The position error on the location of a gravitational wave source is estimated, and is used to show that it could be possible to observe the electromagnetic counterparts to neutron star-neutron star or neutron ...

A review of the neutrino conversion and oscillations among the two neutrino species (active and sterile) induced by strong twisting magnetic field is presented and implications to neutrinos in neutron star, supernova, the Sun and interstellar galactic media are discussed. The “cross-boundary effect” (CBE) (i.e., a possible conversion of one half of neutrinos of the bunch from active into steril...

We have monitored the quasi-persistent neutron-star X-ray transient MXB 1659–29 in quiescence using Chandra. The purpose of our observations was to monitor the quiescent behavior of the source after its last prolonged outburst episode and to study the cooling curve of the neutron star in this system. We discuss the results obtained and how they constrain the properties of the neutron star in MX...

The launch of the Beppo-Sax satellite gave a unique opportunity to investigate gamma ray bursts (GRB) in different spectral regions. The large diversity of the afterglow behavior creates additional problems for the cosmological model with a fireball. Formation of the afterglow giving the observed diversity of properties is suggested in the Galactic neutron star model of GRBs. It is based on the...

A moderate level of variability has been detected in the quiescent luminosity of several neutron star soft X– ray transients. Spectral variability was first revealed by Chandra observations of Aql X-1 in the four months that followed the 2000 X–ray outburst. By adopting the canonical model for quiescent spectrum of soft X–ray transients, i.e. an absorbed neutron star atmosphere model plus a pow...

If core collapse leads to the formation of a rapidly rotating bar-unstable proto-neutron star surrounded by fall-back material, then we might expect it to cool and fragment to form a double (proto)-neutron star binary into a super-close orbit. The lighter star should survive for awhile, until tidal mass loss propels it toward the minimum stable mass of a (proto)-neutron star, whereupon it explo...

Soft X–ray Transients (SXRTs) have long been suspected to contain old, weakly magnetic neutron stars that have been spun up by accretion torques. After reviewing their observational properties, we analyse the different regimes that likely characterise the neutron stars in these systems across the very large range of mass inflow rates, from the peak of the outbursts to the quiescent emission. Wh...