Scalar Quasi-Normal Modes in Black Hole Gravitational Lensing

Abstract

We investigate the excitation of quasi-normal modes (QNMs) in gravitational lensing by a Schwarzschild black hole using a scalar field model. By employing a time-domain mode-sum method, we analyze the complex interplay between an incident burst signal and the black hole spacetime. We find that the incident waves can non-resonantly excite a substantial number of high-$l$ modes, with amplitudes for modes as high as l=20 remaining significant compared to the fundamental l=0 mode. We confirm through QNM template fitting that the late-time behaviors of these excited modes are indeed QNMs. After passing through the black hole, we find that the lensed waves form a highly directional and coherent Gaussian beam whose cross-sectional intensity profile is well-described by a Gaussian profile. Unlike spherical waves, this beam's amplitude does not decrease with distance from the black hole but remains nearly constant in the near-field region. Moreover, due to the superposition of numerous QNMs, oscillations largely cancel each other out. The lensed temporal waves do not exhibit typical oscillatory patterns.

13 pages, 10 figures, accepted for publication in PRD

References in corpus (33)

• Quasinormal modes of black holes and black branes
• Quasi-Normal Modes of Stars and Black Holes
• Quasinormal modes of black holes: from astrophysics to string theory
• Geodesic stability, Lyapunov exponents and quasinormal modes
• The deal.II finite element library: design, features, and insights
• The linear stability of the Schwarzschild solution to gravitational perturbations
• Nonlinearities in Black Hole Ringdowns
• Nonlinear effects in black hole ringdown
• Agnostic black hole spectroscopy: Quasinormal mode content of numerical relativity waveforms and limits of validity of linear perturbation theory
• Extraction of Gravitational Waves in Numerical Relativity
• Detecting Lensing-Induced Diffraction in Astrophysical Gravitational Waves
• Discovering intermediate-mass black hole lenses through gravitational wave lensing
• Detecting Stellar Lensing of Gravitational Waves with Ground-Based Observatories
• Intermediate-mass-ratio black hole binaries: intertwining numerical and perturbative techniques
• Null infinity waveforms from extreme-mass-ratio inspirals in Kerr spacetime
• Identifying Type II Strongly Lensed Gravitational-Wave Images in Third-Generation Gravitational-Wave Detectors
• Lensing of gravitational waves: efficient wave-optics methods and validation with symmetric lenses
• Gravitational lensing of gravitational waves: wave nature and prospects for detection
• Wave Propagation and Quasinormal Mode Excitation on Schwarzschild Spacetime
• The wave nature of continuous gravitational waves from microlensing
• Scattering of gravitational radiation: second order moments of the wave amplitude
• Wave Optics in Black Hole Spacetimes: Schwarzschild Case
• Wave propagation in a weak gravitational field and the validity of the thin lens approximation
• Viewing Black Holes by Waves
• GLoW: novel methods for wave-optics phenomena in gravitational lensing
• A note on gravitational wave lensing
• Absorbing boundary conditions for Einstein's field equations
• Spin wave optics for gravitational waves lensed by a Kerr black hole
• Poisson-Arago spot for gravitational waves
• The detectability of single spinless stellar-mass black holes through gravitational lensing of gravitational waves with advanced LIGO
• Simulating gravitational waves passing through the spacetime of a black hole
• Lensing and wave optics in the strong field of a black hole
• Rigorous calculation of scalar scattering in Schwarzschild background: the convergence of partial-wave series and Poisson spot