Future microhertz detections combined with nanohertz pulsar terms can serve as gravity echoes to measure supermassive black hole binary inspiral rates from hundreds to thousands of years in the past.
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Superradiance -- the 2020 Edition
Canonical reference. 95% of citing Pith papers cite this work as background.
abstract
Superradiance is a radiation enhancement process that involves dissipative systems. With a 60 year-old history, superradiance has played a prominent role in optics, quantum mechanics and especially in relativity and astrophysics. In General Relativity, black-hole superradiance is permitted by the ergoregion, that allows for energy, charge and angular momentum extraction from the vacuum, even at the classical level. Stability of the spacetime is enforced by the event horizon, where negative energy-states are dumped. Black-hole superradiance is intimately connected to the black-hole area theorem, Penrose process, tidal forces, and even Hawking radiation, which can be interpreted as a quantum version of black-hole superradiance. Various mechanisms (as diverse as massive fields, magnetic fields, anti-de Sitter boundaries, nonlinear interactions, etc...) can confine the amplified radiation and give rise to strong instabilities. These "black-hole bombs" have applications in searches of dark matter and of physics beyond the Standard Model, are associated to the threshold of formation of new black hole solutions that evade the no-hair theorems, can be studied in the laboratory by devising analog models of gravity, and might even provide a holographic description of spontaneous symmetry breaking and superfluidity through the gauge-gravity duality. This work is meant to provide a unified picture of this multifaceted subject. We focus on the recent developments in the field, and work out a number of novel examples and applications, ranging from fundamental physics to astrophysics.
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representative citing papers
Using LIGO O3 continuous-wave search data, the authors place the first constraints on ellipticities of self-interacting fermionic dark matter admixed neutron stars and exclude regions of the DM parameter space for masses in [0.1,10] GeV.
An external dynamical environment forms a resonant cavity with a black hole in dCS gravity that triggers Mathieu instability in the scalar sector, producing cascading amplification of gravitational waves via a delayed secondary burst.
Exact transparent radiation boundary conditions and near-to-far field teleportation kernels are derived for the Bardeen-Press equation, approximated via exponential sums with error bounds, and shown to eliminate late-time artifacts in time-domain solvers.
GreyRing model based on greybody factors reproduces numerical relativity ringdown signals with mismatches of order 10^{-6} and enables a new post-merger consistency test of general relativity applied to GW250114.
ABG-dS black holes show charged superradiant instability exclusively for the spherically symmetric ℓ=0 mode, with growth rates that peak at intermediate Λ and q and rise with Q, differing from RN-dS due to nonlinear electrodynamics.
Acceleration radiation for massive vector fields near black hole horizons has a universal thermal detailed-balance factor from the Rindler transformation, with mass thresholds and polarization-dependent spectra, yielding an entropy flux relation identical in form to the scalar HBAR case.
Black hole superradiance constrains the coupling strength in interacting dark energy-dark matter models through modifications to the effective mass of ultralight bosons in two scenarios.
Tailored temporal modulation of incoming signals enables complete absorption by black holes via excitation of complex-plane resonances, storing energy for later release through virtual absorption modes.
Derives a cavity thermal product formula relating bouncing geodesic singularities in the retarded Green's function to the quasinormal mode spectrum for Schwarzschild and Schwarzschild-de Sitter black holes inside a reflecting cavity.
Superradiant axion clouds around black holes can undergo gravitational superfluorescence via a seeded coherent quadrupolar transition, leading to a detectable delayed gravitational-wave pulse.
The equilibrium radius of self-gravitating dark fermion stars is determined by the fermion mass once the total mass is given, with the Bohm potential supplying outward pressure for heavier species and inward tension for lighter ones.
Superradiant axion-like-particle clouds around rotating black holes can generate multimode squeezed graviton states with 10^6-10^7 correlated quanta showing polarization correlations and quantum-noise signatures potentially detectable by future interferometers.
Eccentric EMRIs exhibit relativistic resonances in scalar fluxes that enhance interactions with scalar clouds and amplify waveform dephasing relative to circular orbits.
A unified relativistic framework using bilinear perturbation theory calculates frequency shifts in GWs from axion clouds, handling self-interactions and multiple superradiant modes for the first time.
Time-dependent evolution of a non-rigid Nambu-Goto string around a Kerr black hole produces short-lived energy extraction followed by a propagating wave and approach to a known static configuration, with total extracted energy bounded by μM.
A one-body conformal-factor correction stabilizes boson star-black hole initial data, enabling gravitational-wave analysis that shows higher multipoles can discriminate mixed mergers from pure black-hole binaries.
Relativistic metric backreaction from scalar dark matter clouds in EMRIs produces dominant polar gravitational wave corrections for Mμ ≲ 0.12, exceeding axial and scalar radiation channels at small separations.
Superradiant amplification of charged scalar fields around rotating charged de Sitter black holes is suppressed in conformal Weyl gravity relative to general relativity, with strong exponential suppression for massive fields in the cosmological region.
Quasinormal modes correspond well to grey-body factors for vector and tensor perturbations of Schwarzschild-Tangherlini black holes in all dimensions, but fail for scalar l=2 modes in D≥7 because of multiple potential barriers.
Collective nucleon scattering in neutron-star matter suppresses the effective absorption of ultralight bosons at the long wavelengths relevant for superradiance, weakening the link between stellar cooling bounds and superradiant instability rates.
Excitation factors of long-lived quasinormal modes in horizonless compact objects scale with their small imaginary frequency, suppressing early contributions and producing a hierarchy where prompt ringdown uses ordinary modes and late echoes use cavity modes.
A novel quantity derived from GW signals encodes the density profile of dark dense environments around black holes, allowing characterization of the condensate type and DM properties via multi-wavelength observations.
Semi-analytic waveform model for scalar environments around black hole binaries is validated against numerical relativity and applied to LIGO-Virgo-KAGRA data to obtain upper limits on scalar densities with tentative evidence in GW190728.
citing papers explorer
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Gravity Echoes from Supermassive Black Hole Binaries
Future microhertz detections combined with nanohertz pulsar terms can serve as gravity echoes to measure supermassive black hole binary inspiral rates from hundreds to thousands of years in the past.
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First Constraints on the Ellipticities of Self-Interacting Fermionic Dark Matter Admixed Neutron Stars from Continuous Gravitational-Wave Searches
Using LIGO O3 continuous-wave search data, the authors place the first constraints on ellipticities of self-interacting fermionic dark matter admixed neutron stars and exclude regions of the DM parameter space for masses in [0.1,10] GeV.
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Cascading amplification of gravitational waves triggered by environment in dynamical Chern-Simons gravity
An external dynamical environment forms a resonant cavity with a black hole in dCS gravity that triggers Mathieu instability in the scalar sector, producing cascading amplification of gravitational waves via a delayed secondary burst.
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Radiation outer boundary conditions and near-to-far field signal transformations for the Bardeen-Press equation
Exact transparent radiation boundary conditions and near-to-far field teleportation kernels are derived for the Bardeen-Press equation, approximated via exponential sums with error bounds, and shown to eliminate late-time artifacts in time-domain solvers.
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Novel ringdown tests of general relativity with black hole greybody factors
GreyRing model based on greybody factors reproduces numerical relativity ringdown signals with mismatches of order 10^{-6} and enables a new post-merger consistency test of general relativity applied to GW250114.
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Charged Superradiant Instability of Spherically Symmetric Regular Black Holes in de Sitter Spacetime: Time- and Frequency-Domain Analysis
ABG-dS black holes show charged superradiant instability exclusively for the spherically symmetric ℓ=0 mode, with growth rates that peak at intermediate Λ and q and rise with Q, differing from RN-dS due to nonlinear electrodynamics.
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Bouncing Geodesics, Singularities, and the Cavity Thermal Product Formula in Asymptotically Flat and de Sitter Black Holes
Derives a cavity thermal product formula relating bouncing geodesic singularities in the retarded Green's function to the quasinormal mode spectrum for Schwarzschild and Schwarzschild-de Sitter black holes inside a reflecting cavity.
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Gravitational superfluorescence from superradiant axion clouds
Superradiant axion clouds around black holes can undergo gravitational superfluorescence via a seeded coherent quadrupolar transition, leading to a detectable delayed gravitational-wave pulse.
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Self-gravitating quantum stars with a globally relevant Bohm potential
The equilibrium radius of self-gravitating dark fermion stars is determined by the fermion mass once the total mass is given, with the Bohm potential supplying outward pressure for heavier species and inward tension for lighter ones.
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How Much Can Gravitons Be Squeezed?
Superradiant axion-like-particle clouds around rotating black holes can generate multimode squeezed graviton states with 10^6-10^7 correlated quanta showing polarization correlations and quantum-noise signatures potentially detectable by future interferometers.
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Resonances as signatures of scalar clouds in eccentric extreme-mass-ratio inspirals
Eccentric EMRIs exhibit relativistic resonances in scalar fluxes that enhance interactions with scalar clouds and amplify waveform dephasing relative to circular orbits.
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Relativistic frequency shifts in gravitational waves from axion clouds
A unified relativistic framework using bilinear perturbation theory calculates frequency shifts in GWs from axion clouds, handling self-interactions and multiple superradiant modes for the first time.
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Time evolution of a Nambu-Goto string coiling around a Kerr black hole
Time-dependent evolution of a non-rigid Nambu-Goto string around a Kerr black hole produces short-lived energy extraction followed by a propagating wave and approach to a known static configuration, with total extracted energy bounded by μM.
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Boson star-black hole binaries: initial data and head-on collisions
A one-body conformal-factor correction stabilizes boson star-black hole initial data, enabling gravitational-wave analysis that shows higher multipoles can discriminate mixed mergers from pure black-hole binaries.
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Relativistic signatures of scalar dark matter in extreme-mass-ratio inspirals
Relativistic metric backreaction from scalar dark matter clouds in EMRIs produces dominant polar gravitational wave corrections for Mμ ≲ 0.12, exceeding axial and scalar radiation channels at small separations.
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Superradiant Suppression of Non-minimally Coupled Scalar fields for a Rotating Charged dS Black Hole in Conformal Weyl Gravity
Superradiant amplification of charged scalar fields around rotating charged de Sitter black holes is suppressed in conformal Weyl gravity relative to general relativity, with strong exponential suppression for massive fields in the cosmological region.
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Correspondence between quasinormal modes and grey-body factors of Schwarzschild--Tangherlini black holes
Quasinormal modes correspond well to grey-body factors for vector and tensor perturbations of Schwarzschild-Tangherlini black holes in all dimensions, but fail for scalar l=2 modes in D≥7 because of multiple potential barriers.
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No Evidence for Superradiant Axions in LIGO-Virgo-KAGRA GWTC-5 Binary Black Hole Spins
Hierarchical Bayesian analysis of GWTC-5 binary black hole spins finds no evidence for superradiant axions and excludes masses 1.7e-14 to 3.3e-12 eV at 95% CL.
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Quasibound states of a charged Dirac field around regular black holes
ABG regular black holes modify the lifetimes of charged Dirac quasibound states relative to RN but keep the modes damped without producing superradiant instability in the explored parameter range.
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Finite Coherence in Gravitational Waves from Tidally Excited Axion Clouds
Finite coherence during tidal Bohr crossings in axion clouds produces distinct, localized gravitational-wave waveforms and orbital responses in black-hole binaries.
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String Axiverse Enhancement of Superradiant Dark Matter Production
O(100-10^5) string axions enhance PBH superradiance efficiency via increased spin, expanding viable mass-spin regions for micro-boson star dark matter while too many axions cause overly rapid evaporation.
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Radio Emission from High-Frequency Gravitational Wave Point Sources
Radio telescopes outperform other experiments at detecting high-frequency gravitational waves from primordial black hole mergers and boson clouds through conversion to radio signals in magnetic fields.
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Distorting Kerr Images with Parity-Odd Scalar Hair
Numerical study of thin accretion disk images shows that increasing parity-odd scalar hair on Kerr black holes shrinks and distorts the photon ring and shadow, producing multiple disconnected shadows and chaotic lensing features in strong-hair regimes.
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Dimming of Photon Ring due to Photon-Axion Conversion around Kerr Black Holes
Photon-axion conversion near Kerr black holes produces dimming of photon spectral luminosity that increases with black hole spin, magnetic field strength, and photon-axion coupling, most efficiently at high frequencies.
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Neutron stars more compact than black holes in quasi-topological gravity: Equilibrium configurations and radial stability
In quasi-topological gravity, neutron stars can surpass black-hole compactness with universal high-density behavior and theory corrections that stabilize radially unstable configurations from general relativity.
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Resonant transmission of scalar waves through rotating traversable wormhole
Rotation enhances Breit-Wigner resonances in scalar wave transmission through Teo wormholes by trapping modes in the throat potential well.
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Constraining Ultralight Scalar Dark Matter in the Galactic Center with the S2 Orbit
Using S2 star periastron precession, the work constrains ultralight scalar dark matter mass ratios to below 10^{-3} or 1 and improves quadratic coupling bounds for masses 10^{-20} to 10^{-18} eV.
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High-frequency gravitational wave transients from superradiance
Ultralight boson clouds around primordial black holes emit high-frequency gravitational wave transients via superradiance and binary-driven transitions, but the signals fall below current detector sensitivity at plausible distances.
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Universal Ladder Structure Across Scales: From Quantum to Black Hole Physics
A symmetry-based litmus test identifies when physical systems governed by second-order ODEs possess ladder structures and constructs them, linking supersymmetric quantum mechanics to Kerr black-hole tidal responses.