Long baseline interferometers to detect gravitational waves such as TAMA300 [1], GEO600 [2], VIRGO [3], LIGO [4] will be in operation by the end of this century or the beginning of the 21st century. One of the most important sources of gravitational waves for such detectors are coalescing binary neutron stars. PSR1913+16 is the first binary neutron stars found by Hulse and Taylor. The existence...

We make a first calculation of eigenfrequencies of radial pulsations of neutron stars with quark cores in a general relativistic formalism given by Chandrasekhar. The equations of state (EOS) used to estimate such eigenfrequencies have been derived by taking proper care of the hadron-quark phase transition. The hadronic EOS’s have been obtained in the framework of the Brueckner-Hartree-Fock and...

After a brief introduction to the necessary of quark stars in modelling pulsars, I present a qualitative analysis of the solidification of quark matter with low-temperature but high-density. The reason, that a solid neutron star could not be possible, is also given. Subject headings: pulsars: general — stars: neutron — elementary particles What’s the nature of pulsars? This question seems to ha...

The evolution leading to the formation of a neutron star in the very young Westerlund 1 star cluster is investigated. The turnoff mass has been estimated to be ∼ 35 M⊙, indicating a cluster age ∼ 3 − 5 Myr. The brightest X-ray source in the cluster, CXO J164710.2-455216, is a slowly spinning (10 s) single neutron star and potentially a magnetar. Since this source was argued to be a member of th...

Two classes of neutron stars may exist in the galactic halo: neutron stars originating in the disk with high velocities and neutron stars originating in globular clusters (via Type II supernovae and/or accretion induced collapse).Moreover, the halo dark matter is likely in the form of dark clusters composed of MACHOs and cold molecular clouds. Here we propose a model in which neutron stars cros...

The prescient remark by Baade and Zwicky that supernovae beget neutron stars did little to prepare us for the remarkable variety of observational manifestations such objects display. Indeed, during the first thirty years of the empirical study of neutron stars, only a handful were found to be associated with the remnants of exploded stars. But recent X-ray and radio observations have gone a lon...

The origin of the local population of young, cooling neutron stars is investigated with a population synthesis model taking into account the contribution of neutron stars born in the Gould Belt, in addition to those originating in the Galactic disk. We estimate their emission in the soft X-ray band as a function of distance and age and construct the Log N – Log S distribution. It is shown that ...

We suggest that the unique X-ray source 1E161348-5055 at the centre of the supernova remnant RCW 103 consists of a neutron star in close orbit with a low mass main sequence star. The time signature of 6.67 hr is interpreted as the neutron star’s spin period. This requires the neutron star to be endowed with a high surface magnetic field of ∼ 10 G. Magnetic or/and material (propeller) torques ar...

The last decade has shown us that the observational properties of neutron stars are remarkably diverse. From magnetars to rotating radio transients, from radio pulsars to isolated neutron stars, from central compact objects to millisecond pulsars, observational manifestations of neutron stars are surprisingly varied, with most properties totally unpredicted. The challenge is to establish an ove...

GRB 990123 may have radiated more than one solar mass equivalent in just its gamma emissions. Though this may be within the upper limit of the binding energies available from neutron stars in the Schwarzschild metric, it is difficult to imagine a process with the required efficiency of conversion to gamma rays. Neutron stars of ∼ 10M⊙ are permitted in the Yilmaz metric. A merger of two neutron ...