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Stability of the AdS Soliton Spacetime
강궁원,오창헌,Chul H. Lee 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
The AdS soliton spacetime is a vacuum static solution of five-dimensional Einstein equations with a cosmological constant. It is asymptotically AdS and regular everywhere without having any curvature singularity or an event horizon inside. Recently, Horowitz and Myers conjectured that this spacetime is the ground state among all spacetime solutions that are asymptotically AdS. If such a conjecture is valid, the spacetime should be stable under small perturbations. We have investigated this isue by numericaly studying the ful nonlinear evolution of a certain clas of perturbations. Our results show that some metric components decay out whereas one metric component grows, indicating a sort of instability. Motivated by this result, we also performed a linearized stability analysis for smal perturbations in the same clas. Interestingly, our result in such a linearized analysis does not show any indication of instability. Finaly, we discus the implications of our results on the stability of the AdS soliton background.
Classical Stability of Black Branes
강궁원 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1
Classical stability behaviors of various static black brane backgrounds under small perturbations have been summarized brie y here. They include cases of black strings in AdS5 space, charged black p-brane solutions in the type II supergravity, and the BTZ black string in four-dimensions. The relationship between dynamical stability and local thermodynamic stability - the so-called Gubser-Mitra conjecture - has also been checked for those cases.
Spacetime Structure of 5D Hypercylindrical Vacuum Solutions with Tension
조인용,강궁원,김상표,Chul H. Lee 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
We investigate the geometrical properties of 5D cylindrical vacuum solutions with a transverse sphericalsymmetry. The metric is uniform along the fifth direction and is characterized by tension and mass densities. The solutions are classified by the tension-to-masratio. One particular example is the well-known Schwarzschild black string, which has a curvature singularity enclosed by ahorizon. We focus mainly on the geometries of the other solutions, which poses a naked singularity. The light signal emited by an object approaching the singularity reaches a distant observer in finite time, but is infinitely red-shifted.
이형목,이창환,강궁원,오정근,김정리,오상훈,Lee, Hyung-Mok,Lee, Chang-Hwan,Kang, Gung-Won,Oh, John-J.,Kim, Chung-Lee,Oh, Sang-Hoon 한국천문학회 2011 天文學論叢 Vol.26 No.2
Gravitational waves are predicted by the Einstein's theory of General Relativity. The direct detection of gravitational waves is one of the most challenging tasks in modern science and engineering due to the 'weak' nature of gravity. Recent development of the laser interferometer technology, however, makes it possible to build a detector on Earth that is sensitive up to 100-1000 Mpc for strong sources. It implies an expected detection rate of neutron star mergers, which are one of the most important targets for ground-based detectors, ranges between a few to a few hundred per year. Therefore, we expect that the gravitational-wave observation will be routine within several years. Strongest gravitational-wave sources include tight binaries composed of compact objects, supernova explosions, gamma-ray bursts, mergers of supermassive black holes, etc. Together with the electromagnetic waves, the gravitational wave observation will allow us to explore the most exotic nature of astrophysical objects as well as the very early evolution of the universe. This review provides a comprehensive overview of the theory of gravitational waves, principles of detections, gravitational-wave detectors, astrophysical sources of gravitational waves, and future prospects.
A Fully General Relativistic Numerical Simulation Code for Spherically Symmetric Matter
박동호,조인용,강궁원,이형목 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.3
We present a fully general relativistic open-source code that can be used for simulating a system of spherically symmetric perfect fluid matter. It is based on the Arnowitt-Deser-Misner 3+1 formalism with maximal slicing and isotropic spatial coordinates. For hydrodynamic matter High Resolution Shock Capturing (HRSC) schemes with a monotonized central-difference limiter and approximated Riemann solvers are used in the Eulerian viewpoint. The accuracy and the convergence of our numerical code are verified by performing several test problems. These include a relativistic blast wave, relativistic spherical accretion of matter into a black hole, Tolman-Oppenheimer-Volkoff (TOV) stars and Oppenheimer-Snyder (OS) dust collapses. In particular, a dynamical code test is done for the OS collapse by explicitly performing numerical coordinate transformations between our coordinate system and the one used for the analytic solution. Finally, some TOV star solutions are presented for the Eddington-inspired Born-Infeld gravity theory.