In the present letters we study the propagation of smooth pulses in anomalously dispersive media. We prove that non-analytical but smooth points in a pulse still propagate with the vacuum speed of light, c. It gives a...In the present letters we study the propagation of smooth pulses in anomalously dispersive media. We prove that non-analytical but smooth points in a pulse still propagate with the vacuum speed of light, c. It gives an upper limit for signal velocity as well as the non-continuous points of the envelop of a pulse or its derivatives of arbitrary order do.展开更多
The new four-dimensional geometry whose Killing vectors span the Poincaré algebra is presented and its structure is analyzed.The new geometry can be regarded as the Poincaré-invariant solution of the degener...The new four-dimensional geometry whose Killing vectors span the Poincaré algebra is presented and its structure is analyzed.The new geometry can be regarded as the Poincaré-invariant solution of the degenerate extension of the vacuum Einstein field equations with a negative cosmological constant and provides a static cosmological spacetime with a Lobachevsky space.The motion of free particles in the spacetime is discussed.展开更多
A black hole and its Hawking radiation may be in stable thermal equilibrium.In this letter,the static spherically symmetric numerical solution for a Schwarzschild black hole with its Hawking radiation are obtained.In ...A black hole and its Hawking radiation may be in stable thermal equilibrium.In this letter,the static spherically symmetric numerical solution for a Schwarzschild black hole with its Hawking radiation are obtained.In the calculation,the equilibrium system is supposed to consist of a black hole,thermal radiation and a two-dimensional surface layer.The solutions obtained are compared with the York's back-reaction approach and the Zhao-Liu thermodynamic approach.展开更多
The static spherically symmetric black hole solutions in R+αR^(2) gravity coupled to a massive Yang-Mills field,namely,a Proca field are studied.Through the numerical integrations,it is shown that for positive α,the...The static spherically symmetric black hole solutions in R+αR^(2) gravity coupled to a massive Yang-Mills field,namely,a Proca field are studied.Through the numerical integrations,it is shown that for positive α,there exist two distinct classes of solutions which have the horizon.One class approaches the Schwarzschild solution and the other may be interpreted as black holes with the new hair due to the αR^(2) term.展开更多
We investigate the gravitational collapse of a spherically symmetric, inhomogeneous star, which is described by a perfect fluid with heat flow and satisfies the equation of state p = p/3 at its center. In the process ...We investigate the gravitational collapse of a spherically symmetric, inhomogeneous star, which is described by a perfect fluid with heat flow and satisfies the equation of state p = p/3 at its center. In the process of the gravitational collapse, the energy of the whole star is emitted into space. And the remaining spacetime is a Minkowski one without a remnant at the end of the process. For a star with a solar mass and solar radius, the total energy emitted is at the order of 10^54 erg, and the time-scale of the process is about 8 s. These are in the typical values for a gamma-ray burst. Thus, we suggest the gravitational collapse of a spherical star with heat flow as a possible energy mechanism of gamma-ray bursts.展开更多
The standard and high-order Gaussian beam solutions for gravitational wave is obtained in the linear approximation of vacuum Einstein equation under harmonic conditions.
文摘In the present letters we study the propagation of smooth pulses in anomalously dispersive media. We prove that non-analytical but smooth points in a pulse still propagate with the vacuum speed of light, c. It gives an upper limit for signal velocity as well as the non-continuous points of the envelop of a pulse or its derivatives of arbitrary order do.
基金Supported by the National Natural Science Foundation of China under Grant Nos.10775140,10705048,10731080,10975141,11175245,11075206the Fundamental Research Funds for the Central Universities under Grant No.105116.
文摘The new four-dimensional geometry whose Killing vectors span the Poincaré algebra is presented and its structure is analyzed.The new geometry can be regarded as the Poincaré-invariant solution of the degenerate extension of the vacuum Einstein field equations with a negative cosmological constant and provides a static cosmological spacetime with a Lobachevsky space.The motion of free particles in the spacetime is discussed.
基金Supported in part by the National Natural Science Foundation of China under Grant No.19675046the Climbing up Program of Department of Science and Technology of China.
文摘A black hole and its Hawking radiation may be in stable thermal equilibrium.In this letter,the static spherically symmetric numerical solution for a Schwarzschild black hole with its Hawking radiation are obtained.In the calculation,the equilibrium system is supposed to consist of a black hole,thermal radiation and a two-dimensional surface layer.The solutions obtained are compared with the York's back-reaction approach and the Zhao-Liu thermodynamic approach.
基金Supported in part by the National Natural Science Foundation of China under Grant No.19675046the Climbing Program of Science and Technology Department of China.
文摘The static spherically symmetric black hole solutions in R+αR^(2) gravity coupled to a massive Yang-Mills field,namely,a Proca field are studied.Through the numerical integrations,it is shown that for positive α,there exist two distinct classes of solutions which have the horizon.One class approaches the Schwarzschild solution and the other may be interpreted as black holes with the new hair due to the αR^(2) term.
基金National Natural Science Foundation of China under Grant Nos.90403023 and 10575106the Knowledge Innovation Funds of CAS under Grant No.KJCX3-SYW-S03One of the authors (C.-B.G.) got the support in the initial stage of the present work from the Interdisciplinary Center for Theoretical Study,University of Science and Technology of China
文摘We investigate the gravitational collapse of a spherically symmetric, inhomogeneous star, which is described by a perfect fluid with heat flow and satisfies the equation of state p = p/3 at its center. In the process of the gravitational collapse, the energy of the whole star is emitted into space. And the remaining spacetime is a Minkowski one without a remnant at the end of the process. For a star with a solar mass and solar radius, the total energy emitted is at the order of 10^54 erg, and the time-scale of the process is about 8 s. These are in the typical values for a gamma-ray burst. Thus, we suggest the gravitational collapse of a spherical star with heat flow as a possible energy mechanism of gamma-ray bursts.
文摘The standard and high-order Gaussian beam solutions for gravitational wave is obtained in the linear approximation of vacuum Einstein equation under harmonic conditions.
