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91.
We formulate the general relativistic force-free electrodynamics in a new 3 + 1 language. In this formulation, when we have properly defined electric and magnetic fields, the covariant Maxwell equations could be cast in the traditional form with new vacuum constitutive constraint equations. The fundamental equation governing a stationary, axisymmetric force-free black hole magnetosphere is derived using this formulation which recasts the Grad-Shafranov equation in a simpler way. Compared to the classic 3+1 system of Thorne and MacDonald, the new system of 3+1 equations is more suitable for numerical use for it keeps the hyperbolic structure of the electrodynamics and avoids the singularity at the event horizon. This formulation could be readily extended to non-relativistic limit and find applications in fiat spacetime. We investigate its application to disk wind, black hole magnetosphere and solar physics in both fiat and curved spacetime. 相似文献
92.
The stability of a recently proposed general relativistic model of galaxies is studied in some detail. This model is a general relativistic version of the well-known Miyamoto–Nagai model that represents well a thick galactic disc. The stability of the disc is investigated under a general first-order perturbation keeping the space–time metric frozen (no gravitational radiation is taken into account). We find that the stability is associated with the thickness of the disc. We find that flat galaxies have more non-stable modes than the thick ones, i.e. flat galaxies have a tendency to form more complex structures like rings, bars and spiral arms. 相似文献
93.
Victor Brumberg 《Celestial Mechanics and Dynamical Astronomy》2007,99(3):245-252
The half-century old idea of Infeld to use the variational principle of the general relativity field equations is reminded
to show that the commonly employed EIH (Einstein–Infeld–Hoffman) equations of motion may be derived from the linearized (weak-field)
metric alone. Based on it, the linearized metric might be sufficient for post-Newtonian celestial mechanics and astrometry
enabling one to derive the post-Newtonian equations of motion and rotation of celestial bodies as well as the post-Newtonian
equations of light propagation within the general relativity framework. 相似文献
94.
95.
97.
《New Astronomy》2015
Using the Darmois–Israel formalism the dynamical analysis of Reissner Nordstrom de-Sitter thin shell wormholes, at the wormhole throat, are determined by considering linearized radial perturbations around static solutions.The region of stability in the presence of a large value of charge is significantly increased. Also, the region of stability in the presence of a positive large value of cosmological constant is significantly increased. 相似文献
98.
The post-Newtonian mean anomaly advance as further post-Keplerian parameter in pulsar binary systems
Lorenzo Iorio 《Astrophysics and Space Science》2007,312(3-4):331-335
The post-Newtonian gravitoelectric secular rate of the mean anomaly ℳ is worked out for a two-body system in the framework
of the General Theory of Relativity. The possibility of using such an effect, which is different from the well known decrease
of the orbital period due to gravitational wave emission, as a further post-Keplerian parameter in binary systems including
at least one pulsar is examined. The resulting effect is almost three times larger than the periastron advance
. E.g., for the recently discovered double pulsar system PSR J0737-3039 A+B it would amount to −47.79 deg yr−1. This implies that it could be extracted from the linear part of a quadratic fit of the orbital phase because the uncertainties
both in the linear drift due to the mean motion and in the quadratic shift due to the gravitational wave are smaller. The
availability of such additional post-Keplerian parameter would be helpful in further constraining the General Theory of Relativity,
especially for such systems in which some of the other post-Keplerian parameters can be measured with limited accuracy. Moreover,
also certain pulsar-white dwarf binary systems, characterized by circular orbits like PSR B1855+09 and a limited number of
measured post-Keplerian parameters, could be used for constraining competing theories of gravity. 相似文献
99.
Hajime Sotani Kostas D. Kokkotas 《Monthly notices of the Royal Astronomical Society》2009,395(2):1163-1172
We study polar Alfvén oscillations of relativistic stars endowed with a strong global poloidal dipole magnetic field. Here, we focus only on the axisymmetric oscillations which are studied by numerically evolving the two-dimensional perturbation equations. Our study shows that the spectrum of the polar Alfvén oscillations is discrete in contrast to the spectrum of axial Alfvén oscillations which is continuous. We also show that the typical fluid modes, such as the f and p modes, are not significantly affected by the presence of the strong magnetic field. 相似文献
100.
Our modified gravity theory (MOG) was used successfully in the past to explain a range of astronomical and cosmological observations, including galaxy rotation curves, the cosmic microwave background acoustic peaks, and the galaxy mass power spectrum. MOG was also used successfully to explain the unusual features of the Bullet Cluster 1E0657−558 without exotic dark matter. In the present work, we derive the relativistic equations of motion in the spherically symmetric field of a point source in MOG and, in particular, we derive equations for light bending and lensing. Our results also have broader applications in the case of extended distributions of matter, and they can be used to validate the Bullet Cluster results and provide a possible explanation for the merging clusters in Abell 520. 相似文献