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We find that in general relativity slow down of the pulsar rotation due to the magnetodipolar radiation is more faster for
the strange star with comparison to that for the ordinary neutron star of the same mass. Comparison with astrophysical observations
on pulsars spindown data may provide an evidence for the strange star existence and, thus, serve as a test for distinguishing
it from the neutron star. 相似文献
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We study the structure of electromagnetic field of slowly rotating magnetized star in a Randall-Sundrum II type braneworld.
The star is modeled as a sphere consisting of perfect highly magnetized fluid with infinite conductivity and frozen-in dipolar
magnetic field. Maxwell’s equations for the external magnetic field of the star in the braneworld are analytically solved
in approximation of small distance from the surface of the star. We have also found numerical solution for the electric field
outside the rotating magnetized neutron star in the braneworld in dependence on brane tension. The influence of brane tension
on the electromagnetic energy losses of the rotating magnetized star is underlined. Obtained “brane” corrections are shown
to be relevant and have non-negligible values. In comparison with astrophysical observations on pulsars spindown data they
may provide an evidence for the brane tension and, thus, serve as a test for the braneworld model of the Universe. 相似文献
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B. J. Ahmedov A. A. Abdujabbarov D. B. Fayzullaev 《Astrophysics and Space Science》2013,346(2):507-512
It has been found that in general relativity slow down due to the energy losses through charged particles outflow in plasma magnetosphere strongly depends on star’s compactness parameter and is more faster for the neutron star with comparison to that for the strange star of the same mass. Comparison with astrophysical observations on pulsars spin down precise data may provide important information about star’s compactness parameter and consequently an evidence for the strange star existence and, thus, serve as a test for distinguishing it from the neutron star. 相似文献
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The possibility that the cosmological constant is decaying as the observable universe grows is explored, and we define a cosmological parameter, depending of the vacuum energy and the universe radius, which should be presently ca. 122 orders of magnitude smaller than at the Planck epoch. From it, a new version of the Friedmann equation for a flat universe is obtained, which allows the estimation of the Hubble parameter at any epoch and the reconstruction of the expansion history. The main result is a quasi-linear expansion dynamics in concurrence with a number of previous works. This behavior is compatible with the main features of observational cosmology and avoids the horizon, flatness, cosmological constant, coincidence and age problems without the need of neither inflation nor initial fine-tuning. 相似文献
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We perform a study to describe motion of charged particles under the influence of electromagnetic and gravitational fields of a slowly rotating wormhole with nonvanishing magnetic moment. We present analytic expression for potentials of electromagnetic field for an axially symmetric slowly rotating magnetized wormholes. While addressing important issues regarding the subject, we compare our results of motion around black holes and wormholes in terms of the ratio of radii of event horizons of a black hole and of the throat of a wormhole. It is shown that both radial and circular motions of test bodies in the vicinity of a magnetized wormhole could give rise to a peculiar observational astrophysical phenomenon. 相似文献
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The notion of death line of rotating pulsars is applied to model of oscillating neutron stars. It is shown that the magnetosphere of typical non-rotating oscillating stars may not contain secondary plasma to support the generation of radio emission in the region of open field lines of plasma magnetosphere. 相似文献
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Ernazar B. Abdikamalov Bobomurat J. Ahmedov John C. Miller 《Monthly notices of the Royal Astronomical Society》2009,395(1):443-461
Just as a rotating magnetized neutron star has material pulled away from its surface to populate a magnetosphere, a similar process can occur as a result of neutron-star pulsations rather than rotation. This is of interest in connection with the overall study of neutron star oscillation modes but with a particular focus on the situation for magnetars. Following a previous Newtonian analysis of the production of a force-free magnetosphere in this way Timokhin et al., we present here a corresponding general-relativistic analysis. We give a derivation of the general relativistic Maxwell equations for small-amplitude arbitrary oscillations of a non-rotating neutron star with a generic magnetic field and show that these can be solved analytically under the assumption of low current density in the magnetosphere. We apply our formalism to toroidal oscillations of a neutron star with a dipole magnetic field and find that the low current density approximation is valid for at least half of the oscillation modes, similarly to the Newtonian case. Using an improved formula for the determination of the last closed field line, we calculate the energy losses resulting from toroidal stellar oscillations for all of the modes for which the size of the polar cap is small. We find that general relativistic effects lead to shrinking of the size of the polar cap and an increase in the energy density of the outflowing plasma. These effects act in opposite directions but the net result is that the energy loss from the neutron star is significantly smaller than suggested by the Newtonian treatment. 相似文献
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Isofrequency pairing of circular orbits in Schwarzschild spacetime in the presence of magnetic field
Sanjar Shaymatov Farruh Atamurotov Bobomurat Ahmedov 《Astrophysics and Space Science》2014,350(1):413-419
We study isofrequency pairing of the circular non-geodesic orbits in the vicinity of the Schwarzschild black hole immersed in external asymptotically uniform magnetic field. The dependence of the isofrequency pairing of non-geodesic orbits from the special quantities, such as radius of the innermost stable circular orbits (ISCO), radius of the circular orbits (r b ) at the limit e(eccentricity)→0, and from the value of the small quantity ξ=(r b ?r ISCO) of the particles moving around the Schwarzschild black hole in the presence of the magnetic field has been found. It is shown that presence of the magnetic field gives rise to the r ISCO and r b of the particles to be slightly shifted from black hole and the contribution of the quantity ξ decreases the amount of isofrequency pairing of non-geodesic orbits due to the reduction of the surface of the region between the separatrix and circular-orbit duals (COD). We study the dependence of surface of region where particles can move and isofrequency pairing of non-geodesic orbits occur around the Schwarzschild black hole from the magnetic field. We find a decrease of nearly (7–10) % for the maximal values of the magnetic field B～106–107 Gauss in the surface of region where isofrequency pairing occurs around central object with compare to the one around Schwarzschild black hole without magnetic field. This result implies that it makes easier to identify signals through the astrophysical observations of compact objects in the presence of magnetic field. 相似文献
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