scholarly journals A matrix method for quasinormal modes: Kerr and Kerr–Sen black holes

2017 ◽  
Vol 32 (25) ◽  
pp. 1750134 ◽  
Author(s):  
Kai Lin ◽  
Wei-Liang Qian ◽  
Alan B. Pavan ◽  
Elcio Abdalla

In this paper, a matrix method is employed to study the scalar quasinormal modes of Kerr as well as Kerr–Sen black holes. Discretization is applied to transfer the scalar perturbation equation into a matrix form eigenvalue problem, where the resulting radial and angular equations are derived by the method of separation of variables. The eigenvalues, quasinormal frequencies [Formula: see text] and angular quantum numbers [Formula: see text], are then obtained by numerically solving the resultant homogeneous matrix equation. This work shows that the present approach is an accurate, as well as efficient method for investigating quasinormal modes.


2020 ◽  
Vol 35 (23) ◽  
pp. 2050193
Author(s):  
Cai-Ying Shao ◽  
Yu Hu ◽  
Yu-Jie Tan ◽  
Cheng-Gang Shao ◽  
Kai Lin ◽  
...  

In this paper, we study the quasinormal modes of the massless Dirac field for charged black holes in Rastall gravity. The spherically symmetric black hole solutions in question are characterized by the presence of a power-Maxwell field, surrounded by the quintessence fluid. The calculations are carried out by employing the WKB approximations up to the 13th-order, as well as the matrix method. The temporal evolution of the quasinormal modes is investigated by using the finite difference method. Through numerical simulations, the properties of the quasinormal frequencies are analyzed, including those for the extremal black holes. Among others, we explore the case of a second type of extremal black holes regarding the Nariai solution, where the cosmical and event horizon coincide. The results obtained by the WKB approaches are found to be mostly consistent with those by the matrix method. It is observed that the magnitudes of both real and imaginary parts of the quasinormal frequencies increase with increasing [Formula: see text], the spin–orbit quantum number. Also, the roles of the parameters [Formula: see text] and [Formula: see text], associated with the electric charge and the equation of state of the quintessence field, respectively, are investigated regarding their effects on the quasinormal frequencies. The magnitude of the electric charge is found to sensitively affect the time scale of the first stage of quasinormal oscillations, after which the temporal oscillations become stabilized. It is demonstrated that the black hole solutions for Rastall gravity in asymptotically flat spacetimes are equivalent to those in Einstein gravity, featured by different asymptotical spacetime properties. As one of its possible consequences, we also investigate the behavior of the late-time tails of quasinormal models in the present model. It is found that the asymptotical behavior of the late-time tails of quasinormal modes in Rastall theory is governed by the asymptotical properties of the spacetimes of their counterparts in Einstein gravity.



2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Supakchai Ponglertsakul ◽  
Bogeun Gwak

AbstractThis study investigates the stability of higher-dimensional singly rotating Myers-Perry–de Sitter (MP–dS) black holes against scalar field perturbations. The phase spaces of MP-dS black holes with one spin parameter are discussed. Additionally, the quasinormal modes (QNMs) of MP-dS black holes are calculated via the asymptotic iteration method and sixth-order Wentzel–Kramers–Brillouin approximation. For near-extremal MP-dS black holes, the event horizon may be considerably close to the cosmological horizon. In such cases, the Pöschl–Teller technique yields an accurate analytic formula for the QNMs. It is found that when the spin parameter of a black hole increases, the scalar perturbation modes oscillate at higher frequencies and decay faster. Furthermore, the MP-dS black hole with a single rotation is found to be stable under perturbation.



2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Almendra Aragón ◽  
Ramón Bécar ◽  
P. A. González ◽  
Yerko Vásquez


2021 ◽  
Vol 103 (12) ◽  
Author(s):  
Jamie Bamber ◽  
Oliver J. Tattersall ◽  
Katy Clough ◽  
Pedro G. Ferreira


2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Navid Abbasi ◽  
Matthias Kaminski

Abstract We consider a holographic thermal state and perturb it by a scalar operator whose associated real-time Green’s function has only gapped poles. These gapped poles correspond to the non-hydrodynamic quasinormal modes of a massive scalar perturbation around a Schwarzschild black brane. Relations between pole-skipping points, critical points and quasinormal modes in general emerge when the mass of the scalar and hence the dual operator dimension is varied. First, this novel analysis reveals a relation between the location of a mode in the infinite tower of quasinormal modes and the number of pole-skipping points constraining its dispersion relation at imaginary momenta. Second, for the first time, we consider the radii of convergence of the derivative expansions about the gapped quasinormal modes. These convergence radii turn out to be bounded from above by the set of all pole-skipping points. Furthermore, a transition between two distinct classes of critical points occurs at a particular value for the conformal dimension, implying close relations between critical points and pole-skipping points in one of those two classes. We show numerically that all of our results are also true for gapped modes of vector and tensor operators.



2015 ◽  
Vol 2015 (4) ◽  
Author(s):  
Roberto Emparan ◽  
Ryotaku Suzuki ◽  
Kentaro Tanabe






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