Methods of finding quasi-normal modes of non-rotating relativistic stars have been well established, however, none of the existing treatments which take spacetime and fluid oscillations fully into account can determin...Methods of finding quasi-normal modes of non-rotating relativistic stars have been well established, however, none of the existing treatments which take spacetime and fluid oscillations fully into account can determine modes of long decay time, e.g., the p and g mode series, or the f modes for stars with low compactness ratio （M/R）. In this paper we show how the quasi-normal modes of long lifetime can be determined through refinements of a treatment originally due to Detweiler and Lindblom. The determination of the p mode series has been argued in the literature to have implication on the life time of gravitational wave sources and stellar stability. In this paper we 1） provide detailed steps in our treatment to facilitate future effort in this direction; 2） correct mistakes in the literature on the formulation; and 3） analyse the accuracy of the quasi-normal mode frequencies obtained and the limitations of the treatment.展开更多
In this paper, we study the gravitational quasi-normal modes（QNMs） for a static R^2 black hole（BH） in Anti-de Sitter（AdS） spacetime. The corresponding master equation of odd parity is derived and the QNMs are ev...In this paper, we study the gravitational quasi-normal modes（QNMs） for a static R^2 black hole（BH） in Anti-de Sitter（AdS） spacetime. The corresponding master equation of odd parity is derived and the QNMs are evaluated by the Horowitz and Hubeny method. Meanwhile the stability of such BH is also discussed through the temporal evolution of the perturbation field. Here we mainly consider the coefficient λ, which is related to the radius of AdS black hole, on the QNMs of the R^2 AdS BH. The results show that the Re（ω） and ｜Im（ω）｜ of the QNMs increase together as ｜λ｜ increases for a given angular momentum number l. That indicates with a larger value of ｜λ｜ the corresponding R^2 AdS BH returns to stable much more quickly. The dynamic evolution of the perturbation field is consistent with the results derived by the Horowitz and Hubeny method. Since in the conformal field theory the QNMs can reflect its approach to equilibrium, so our related results could be referential to studies of the AdS/CFT conjecture. The relationship between λ and the properties of the static R^2 BH might be helpful for the development of R^2 gravitational theory.展开更多
We model analytically a relativistic problem consisting of two quasi-particles each with mass m in close orbit around a static Schwarzschild black hole with mass M = 1 situated at the center of mass of the system. The...We model analytically a relativistic problem consisting of two quasi-particles each with mass m in close orbit around a static Schwarzschild black hole with mass M = 1 situated at the center of mass of the system. The angular momentum l of the system is taken to be 2. We model the mass density of the orbiting particles as a δ-function and we assume that there are no deformations. To model the system, we apply the second-order differential equation obtained elsewhere for a dynamic thin matter shell on a Schwarzschild background. As it is the case in this paper, the framework on which the equation was obtained is Bodi-Sachs. The only change in the equation is that now the quasi-normal mode parameter represents the particle’s orbital frequency from which we are able to analytically compute the gravitational radiation emitted by the system at null infinity. We note that in a real astrophysical scenario the dynamics of the particles paths will be very dynamic and complicated and that the analytical methods used here will have to be developed further to accommodate that.展开更多
Dynamically controlling terahertz(THz)waves with an ultracompact device is highly desired,but previously realized tunable devices are bulky in size and/or exhibit limited light-tuning functionalities.Here,we experimen...Dynamically controlling terahertz(THz)waves with an ultracompact device is highly desired,but previously realized tunable devices are bulky in size and/or exhibit limited light-tuning functionalities.Here,we experimentally demonstrate dynamic modulation on THz waves with a dielectric metasurface in modeselective or mode-unselective manners through pumping the system at different optical wavelengths.Quasi-normal-mode theory reveals that the physics is governed by the spatial overlap between wave functions of resonant modes and regions inside resonators perturbed by pump laser excitation at different wavelengths.We further design/fabricate a dielectric metasurface and experimentally demonstrate that it can dynamically control the polarization state of incident THz waves,dictated by the strength and wavelength of the pumping light.We finally numerically demonstrate pump wavelength-controlled optical information encryption based on a carefully designed dielectric metasurface.Our studies reveal that pump light wavelength can be a new external knob to dynamically control THz waves,which may inspire many tunable metadevices with diversified functionalities.展开更多
基金the Chinese National Youth Thousand Talents Program(No.KJ2030220006)the USTC start-up(No.KY2030000049)+6 种基金NSFC(Nos.11421303,11653002)the Chinese National Youth Thousand Talents Programthe SYSU Junior Faculty FundPhysics Department at Caltechthe Fund for Fostering Talents in Basic Science of NSFC(No.J1310021)NSFC(No.11205058)the Fundamental Research Funds for Central Universities and by the Open Project Program of State Key Laboratory of Theoretical Physics at CAS(No.Y5KF161CJ1)。
基金the Chinese National Youth Thousand Talents Program(No.KJ2030220006)the USTC start-up(No.KY2030000049)+7 种基金NSFC(Nos.11421303,11653002)the Chinese National Youth Thousand Talents Programthe SYSU Junior Faculty Fundthe physics department at Caltechthe Fund for Fostering Talents in Basic Science of NSFC(No.J1310021)NSFC(No.11205058)by the Fundamental Research Funds for Central Universitiesthe Open Project Program of State Key Laboratory of Theoretical Physics at CAS(No.Y5KF161CJ1).
基金supported by the Science Foundation of the Education Department of Hunan Province of China (Grant No. 07c578)in part by the US National Science Foundation NRACthe McDonnell Center for the Space Sciences of the Washington University(Grant No. MCA93S025)
文摘Methods of finding quasi-normal modes of non-rotating relativistic stars have been well established, however, none of the existing treatments which take spacetime and fluid oscillations fully into account can determine modes of long decay time, e.g., the p and g mode series, or the f modes for stars with low compactness ratio （M/R）. In this paper we show how the quasi-normal modes of long lifetime can be determined through refinements of a treatment originally due to Detweiler and Lindblom. The determination of the p mode series has been argued in the literature to have implication on the life time of gravitational wave sources and stellar stability. In this paper we 1） provide detailed steps in our treatment to facilitate future effort in this direction; 2） correct mistakes in the literature on the formulation; and 3） analyse the accuracy of the quasi-normal mode frequencies obtained and the limitations of the treatment.
基金supported by the National Natural Science Foundation of China(Grant Nos.11205254,11178018,11375279,and 11605015)the Fundamental Research Funds for the Central Universities,China(Grant Nos.106112016CDJXY300002 and CDJRC10300003)+1 种基金the Chinese State Scholarship Fund,FAPESP(Grant No.2012/08934-0)the Natural Science Foundation Project of CQ CSTC(Grant No.2011BB0052)
文摘In this paper, we study the gravitational quasi-normal modes（QNMs） for a static R^2 black hole（BH） in Anti-de Sitter（AdS） spacetime. The corresponding master equation of odd parity is derived and the QNMs are evaluated by the Horowitz and Hubeny method. Meanwhile the stability of such BH is also discussed through the temporal evolution of the perturbation field. Here we mainly consider the coefficient λ, which is related to the radius of AdS black hole, on the QNMs of the R^2 AdS BH. The results show that the Re（ω） and ｜Im（ω）｜ of the QNMs increase together as ｜λ｜ increases for a given angular momentum number l. That indicates with a larger value of ｜λ｜ the corresponding R^2 AdS BH returns to stable much more quickly. The dynamic evolution of the perturbation field is consistent with the results derived by the Horowitz and Hubeny method. Since in the conformal field theory the QNMs can reflect its approach to equilibrium, so our related results could be referential to studies of the AdS/CFT conjecture. The relationship between λ and the properties of the static R^2 BH might be helpful for the development of R^2 gravitational theory.
文摘We model analytically a relativistic problem consisting of two quasi-particles each with mass m in close orbit around a static Schwarzschild black hole with mass M = 1 situated at the center of mass of the system. The angular momentum l of the system is taken to be 2. We model the mass density of the orbiting particles as a δ-function and we assume that there are no deformations. To model the system, we apply the second-order differential equation obtained elsewhere for a dynamic thin matter shell on a Schwarzschild background. As it is the case in this paper, the framework on which the equation was obtained is Bodi-Sachs. The only change in the equation is that now the quasi-normal mode parameter represents the particle’s orbital frequency from which we are able to analytically compute the gravitational radiation emitted by the system at null infinity. We note that in a real astrophysical scenario the dynamics of the particles paths will be very dynamic and complicated and that the analytical methods used here will have to be developed further to accommodate that.
基金the National Key Research and Development Program of China(Grant No.2022YFA1404700)the National Natural Science Foundation of China(Grant Nos.12221004,11734007,and 11874121)the Natural Science Foundation of Shanghai(Grant Nos.20JC1414601 and 19JC1410900)。
文摘Dynamically controlling terahertz(THz)waves with an ultracompact device is highly desired,but previously realized tunable devices are bulky in size and/or exhibit limited light-tuning functionalities.Here,we experimentally demonstrate dynamic modulation on THz waves with a dielectric metasurface in modeselective or mode-unselective manners through pumping the system at different optical wavelengths.Quasi-normal-mode theory reveals that the physics is governed by the spatial overlap between wave functions of resonant modes and regions inside resonators perturbed by pump laser excitation at different wavelengths.We further design/fabricate a dielectric metasurface and experimentally demonstrate that it can dynamically control the polarization state of incident THz waves,dictated by the strength and wavelength of the pumping light.We finally numerically demonstrate pump wavelength-controlled optical information encryption based on a carefully designed dielectric metasurface.Our studies reveal that pump light wavelength can be a new external knob to dynamically control THz waves,which may inspire many tunable metadevices with diversified functionalities.
