Superradiant instabilities of rotating black holes in the time domain
By Sam R. Dolan. 2012
141 citations recorded by the source corpus.
Bosonic fields on rotating black hole spacetimes are subject to amplification by superradiance, which induces exponentially-growing instabilities (the “black hole bomb”) in two scenarios: if the black hole is enclosed by a mirror, or if the bosonic field has rest mass. Here we present a time-domain study of the scalar field on Kerr spacetime which probes ultra-long timescales up to t≲5×106M, to reveal the growth of the instability. We describe a highly-efficient method for evolving the field, based on a spectral decomposition into a coupled set of 1+1D equations, and an absorbing boundary condition inspired by the “perfectly-matched layers” paradigm. First, we examine the mirror case to study how the instability timescale and mode structure depend on mirror radius. Next, we examine the massive-field, whose rich spectrum (revealed through Fourier analysis) generates “beating” effects which disguise the instability. We show that the instability is clearly revealed by tracking the stress-energy of the field in the exterior spacetime. We calculate the growth rate for a range of mass couplings, by applying a frequency-filter to isolate individual modal contributions to the time-domain signal. Our results are in accord with previous frequency-domain studies which put the maximum growth rate at τ-1≈1.72×10-7(GM/c3)-1 for the massive scalar field on Kerr spacetime.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/98dddb78e80931a4fffdf173a7b7a978e28f4dee
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Citations in the corpus
- Constraining the mass of dark photons and axion-like particles through black-hole superradiance (2018, background): “For scalars, the linearized instability regime is very well understood, both from frequency-domain calculations [31–34] and from time-domain evolutions [42].”
- Superradiance: Energy Extraction, Black-Hole Bombs and Implications for Astrophysics and Particle Physics (2015, methodology): “When both time-domain and frequency-domain computations are available, they yield consistent results [282, 100].”
- Numerical methods for finding stationary gravitational solutions (2015, background): “Dirichlet walls can be provided by a reflecting box [421–440], by a massive scalar or Proca field potential well [34, 73, 294, 419, 429, 441–448], or by the AdS boundary with reflecting boundary conditions [38–41, 44, 226, 279, 396, 449, 450].”
- Superradiance (2015, methodology): “[106] by adapting a 3+1 code, whereas subsequently an elegant decomposition in spherical harmonics was used to reduce the KleinGordon equation to an infinite set of hyperbolic partial differential equations for perturbations with different harmonic indices, which can then be solved with a 1 + 1 code”
- The spectra of gravitational atoms (2019, background): “While superradiance with scalar fields has been studied extensively in the past [6–18], the exploration of vector fields is much more recent [19–28].”