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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Unveiling the Gravitational Universe at \mu-Hz Frequencies
Canonical reference. 94% of citing Pith papers cite this work as background.
abstract
We propose a space-based interferometer surveying the gravitational wave (GW) sky in the milli-Hz to $\mu$-Hz frequency range. By the 2040s', the $\mu$-Hz frequency band, bracketed in between the Laser Interferometer Space Antenna (LISA) and pulsar timing arrays, will constitute the largest gap in the coverage of the astrophysically relevant GW spectrum. Yet many outstanding questions related to astrophysics and cosmology are best answered by GW observations in this band. We show that a $\mu$-Hz GW detector will be a truly overarching observatory for the scientific community at large, greatly extending the potential of LISA. Conceived to detect massive black hole binaries from their early inspiral with high signal-to-noise ratio, and low-frequency stellar binaries in the Galaxy, this instrument will be a cornerstone for multimessenger astronomy from the solar neighbourhood to the high-redshift Universe.
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background 17representative citing papers
Radiative corrections from an asymmetric Dirac fermion generate a bias that collapses domain walls, producing gravitational waves that encode the asymmetry level and temperature.
Accounting for the minimal mass spread of primordial black holes from gravitational collapse suppresses the Poltergeist GW background to the level of generic scalar-induced signals and reopens ultra-light PBH parameter space.
Full numerical N-body treatment is required for reliable gravitational wave predictions from nonspherical collapse in early matter-dominated eras, with resulting spectra mappable to detector sensitivities via horizon mass and reheating temperature.
Bubble collisions in a seesaw model produce right-handed neutrinos that source novel gravitational waves detectable by LISA, ET, and LVK while allowing the lightest RHN to explain dark matter or enable leptogenesis.
PPO reinforcement learning accelerates identification of gravitational wave signals from supercooled phase transitions in a minimal dark U(1)_x sector compared to Monte Carlo sampling.
Incorporating the general-relativity mass tail df_PBH/d ln M ∝ M^3.78 smooths PBH evaporation, suppresses the scalar-induced GW signal by orders of magnitude, and reopens the ultra-light PBH window for the hot Big Bang.
Beyond-GR polarization modes in a single supermassive black hole binary show up linearly (not quadratically) in pulsar-timing cross-correlations, massive-graviton dispersion shifts antenna patterns and pulsar-term phases, and most parity-violating birefringence is suppressed at nanohertz frequencies
Domain wall annihilation imprints a two-peaked spectrum on induced gravitational waves via an early matter-dominated phase and entropy dilution.
Spectral features of primordial gravitational-wave backgrounds can directly reconstruct the mass and decay rate of long-lived BSM particles via the frequencies imprinted by an early matter-dominated epoch.
Temperature-dependent DM couplings mediated by a scalar field's VEV that drops after a first-order phase transition allow sufficient early-universe annihilations for the observed relic density while evading current direct detection bounds.
Lattice simulations of bumpy axion U(1) inflation in the strong backreaction regime generate curvature perturbations large enough for primordial black holes to comprise all dark matter.
Radiative barriers in SUSY flat directions enable supercooled PTs yielding Ω_GW h² up to ~3e-10 for M_λ̃/v_X in 0.05-0.23, with the hidden sector also reproducing Ω_CDM h²=0.12 for m_q ~30-800 keV.
Gauged U(1)_F flavor symmetries shield the axion from quantum gravity corrections, yielding unit domain wall number and a plateau-valley GW spectrum from flavonic and axionic strings as a probe of flavored axion dark matter.
Gravitino masses in the 100 TeV to 10^10 TeV range can be inferred from two frequency features in the stochastic gravitational wave spectrum produced by an early matter-dominated phase.
Axion-like particles in the trapped misalignment mechanism produce observable gravitational waves while generating intergalactic magnetic fields that exceed blazar lower bounds in the parameter space promising for gravitational wave detection.
Tensor perturbations from FOPT and domain-wall sources are claimed to induce second-order scalar perturbations large enough to form primordial black holes, potentially all of the dark matter.
ALP-assisted first-order phase transitions can explain observed intergalactic magnetic fields and produce detectable gravitational waves, linking cosmology with particle physics searches.
High-quality axion models with N_DW=1 and dark matter abundance requirement restrict the gauge breaking scale to 1.6e11-1e16 GeV, yielding a band of gravitational wave signals from two-step phase transitions consistent with current observations.
A spectator scalar field with strong portal coupling to the inflaton sources a stochastic gravitational wave background reaching Ω_GW h² ∼ 10^{-11} at frequencies 10^7-10^8 Hz for benchmark parameters σ/λ ≃ 10^4 and T_reh = 2×10^{14} GeV.
A dimension-six operator |H|^2|phi|^4 in a U(1)_D singlet extension relaxes the usual Higgs-portal and mixing-angle correlation, enabling strong first-order electroweak phase transitions driven primarily by the singlet VEV.
Lepton parity stabilizes a Majorana fermion as freeze-in dark matter produced via right-handed neutrino or Higgs decays, yielding detectable gravitational waves or ΔN_eff depending on scalar couplings.
Dark matter freezes in from non-thermal Z' decays before reheating ends in an inflationary model with a secluded U(1)_D gauge sector, Z' reheaton, and lattice treatment of non-perturbative effects, opening viable parameter space with GW probes.
A spectator scalar in modulated reheating with large Higgs-like couplings generates detectable scalar-induced stochastic gravitational waves for BBO and DECIGO, but only outside perturbative low-energy extrapolations.
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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Imprint of matter-antimatter asymmetry on collapsing domain walls
Radiative corrections from an asymmetric Dirac fermion generate a bias that collapses domain walls, producing gravitational waves that encode the asymmetry level and temperature.
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Gravitational Waves from Black Hole Reheating: The Scalar-Induced Component
Accounting for the minimal mass spread of primordial black holes from gravitational collapse suppresses the Poltergeist GW background to the level of generic scalar-induced signals and reopens ultra-light PBH parameter space.
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Gravitational wave emission from nonspherical collapse in an early matter-dominated era using N-body simulations
Full numerical N-body treatment is required for reliable gravitational wave predictions from nonspherical collapse in early matter-dominated eras, with resulting spectra mappable to detector sensitivities via horizon mass and reheating temperature.
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Cosmic Collider Gravitational Waves sourced by Right-handed Neutrino production from Bubbles: Testing Seesaw, Leptogenesis and Dark Matter
Bubble collisions in a seesaw model produce right-handed neutrinos that source novel gravitational waves detectable by LISA, ET, and LVK while allowing the lightest RHN to explain dark matter or enable leptogenesis.
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Supercool with PPO: Exploring Supercooled Phase Transitions via Reinforcement Learning
PPO reinforcement learning accelerates identification of gravitational wave signals from supercooled phase transitions in a minimal dark U(1)_x sector compared to Monte Carlo sampling.
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Opening the Window of Ultra-Light PBHs by Exorcising the Poltergeist
Incorporating the general-relativity mass tail df_PBH/d ln M ∝ M^3.78 smooths PBH evaporation, suppresses the scalar-induced GW signal by orders of magnitude, and reopens the ultra-light PBH window for the hot Big Bang.
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Testing General Relativity with Individual Supermassive Black Hole Binaries
Beyond-GR polarization modes in a single supermassive black hole binary show up linearly (not quadratically) in pulsar-timing cross-correlations, massive-graviton dispersion shifts antenna patterns and pulsar-term phases, and most parity-violating birefringence is suppressed at nanohertz frequencies
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Imprint of domain wall annihilation on induced gravitational waves
Domain wall annihilation imprints a two-peaked spectrum on induced gravitational waves via an early matter-dominated phase and entropy dilution.
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Irreducible Gravitational Wave Background as a Particle Detector
Spectral features of primordial gravitational-wave backgrounds can directly reconstruct the mass and decay rate of long-lived BSM particles via the frequencies imprinted by an early matter-dominated epoch.
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Reviving WIMP dark matter with temperature-dependent couplings
Temperature-dependent DM couplings mediated by a scalar field's VEV that drops after a first-order phase transition allow sufficient early-universe annihilations for the observed relic density while evading current direct detection bounds.
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Lattice study of primordial black hole formation in bumpy axion inflation
Lattice simulations of bumpy axion U(1) inflation in the strong backreaction regime generate curvature perturbations large enough for primordial black holes to comprise all dark matter.
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Natural Supercooling and Reheating along Supersymmetric Flat Directions and Observable Gravitational Waves at the Einstein Telescope and the Cosmic Explorer
Radiative barriers in SUSY flat directions enable supercooled PTs yielding Ω_GW h² up to ~3e-10 for M_λ̃/v_X in 0.05-0.23, with the hidden sector also reproducing Ω_CDM h²=0.12 for m_q ~30-800 keV.
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Gravitational Wave Imprints of a High-Quality Axion and the Origin of Flavor Hierarchies
Gauged U(1)_F flavor symmetries shield the axion from quantum gravity corrections, yielding unit domain wall number and a plateau-valley GW spectrum from flavonic and axionic strings as a probe of flavored axion dark matter.
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Whispers of Supergravity in Gravitational Wave Backgrounds: Determining the Gravitino Mass from Cosmic Thermal History
Gravitino masses in the 100 TeV to 10^10 TeV range can be inferred from two frequency features in the stochastic gravitational wave spectrum produced by an early matter-dominated phase.
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Audible Axion Magnetogenesis: Linking Intergalactic Magnetic Fields and Gravitational Waves
Axion-like particles in the trapped misalignment mechanism produce observable gravitational waves while generating intergalactic magnetic fields that exceed blazar lower bounds in the parameter space promising for gravitational wave detection.
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Primordial Black Hole from Tensor-induced Density Fluctuation: First-order Phase Transitions and Domain Walls
Tensor perturbations from FOPT and domain-wall sources are claimed to induce second-order scalar perturbations large enough to form primordial black holes, potentially all of the dark matter.
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Primordial Magnetogenesis and Gravitational Waves from ALP-assisted Phase Transition
ALP-assisted first-order phase transitions can explain observed intergalactic magnetic fields and produce detectable gravitational waves, linking cosmology with particle physics searches.
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Probing High-Quality Axions with Gravitational Waves
High-quality axion models with N_DW=1 and dark matter abundance requirement restrict the gauge breaking scale to 1.6e11-1e16 GeV, yielding a band of gravitational wave signals from two-step phase transitions consistent with current observations.
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Gravitational Waves from Matter Perturbations of Spectator Scalar Fields
A spectator scalar field with strong portal coupling to the inflaton sources a stochastic gravitational wave background reaching Ω_GW h² ∼ 10^{-11} at frequencies 10^7-10^8 Hz for benchmark parameters σ/λ ≃ 10^4 and T_reh = 2×10^{14} GeV.
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Electroweak phase transitions in a $U(1)_D$ extension of the standard model with dimension-six operators: Gravitational waves and LHC signatures
A dimension-six operator |H|^2|phi|^4 in a U(1)_D singlet extension relaxes the usual Higgs-portal and mixing-angle correlation, enabling strong first-order electroweak phase transitions driven primarily by the singlet VEV.
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Cosmological Probes of Lepton Parity Freeze-in Dark Matter: $\Delta N_{\rm eff}$ & Gravitational Waves
Lepton parity stabilizes a Majorana fermion as freeze-in dark matter produced via right-handed neutrino or Higgs decays, yielding detectable gravitational waves or ΔN_eff depending on scalar couplings.
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Dark Matter Freeze-in from a $Z^\prime$ Reheaton
Dark matter freezes in from non-thermal Z' decays before reheating ends in an inflationary model with a secluded U(1)_D gauge sector, Z' reheaton, and lattice treatment of non-perturbative effects, opening viable parameter space with GW probes.
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Stochastic Gravitational Waves from Modulated Reheating
A spectator scalar in modulated reheating with large Higgs-like couplings generates detectable scalar-induced stochastic gravitational waves for BBO and DECIGO, but only outside perturbative low-energy extrapolations.
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Gravitational Wave Signature and the Nature of Neutrino Masses: Majorana, Dirac, or Pseudo-Dirac?
In the minimal B-L gauge extension, Majorana neutrinos at high breaking scale produce flat GW spectra from cosmic strings, Dirac at low scale produce peaked spectra from first-order phase transitions, and pseudo-Dirac produce kink features from domain wall annihilation.
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Lepton parity dark matter and naturally unstable domain walls
Lepton parity stabilizes a Majorana fermion dark matter candidate while an accidental Z2 symmetry in the scalar potential creates unstable domain walls whose decay produces observable gravitational waves.
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Numerical simulations of density perturbation and gravitational wave production from cosmological first-order phase transition
3D simulations of cosmological first-order phase transitions find density perturbation spectra with k^3 and k^{-1.5} slopes and GW spectra with k^3 and k^{-2}, confirming slow transitions can produce PBHs.
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Majoron Dark Matter, High-Scale Seesaw, and Leptogenesis
Majoron dark matter is viable for sub-MeV masses in high-scale seesaw models with thermal leptogenesis, produced via misalignment and cosmic strings in pre- and post-inflationary scenarios and constrained by CMB, X-ray, and gravitational wave observations.
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Gravitational Waves from hybrid defects as probe of Flavor symmetry breaking: Machine-Learning Approach
Hybrid string-bounded domain wall networks from sequential U(1)_F and Z2 symmetry breaking generate a GW spectrum with a unique low-frequency slope that future detectors can observe and an MLP surrogate can characterize for fast SNR inference.
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From WIMP to FIMP during reheating: collider vs non-collider probes for p-wave annihilation
Collider experiments can strongly constrain p-wave-suppressed derivative operators and thereby limit reheating temperature, DM mass, and interaction scale needed to match observed DM abundance during reheating.
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Probing Dynamical Inverse Seesaw with Low-frequency Gravitational Waves
Dynamical inverse seesaw predicts low-frequency stochastic GW signals from a first-order phase transition, with complementarity to heavy neutral lepton searches at small active-sterile mixing.
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TransitionListener v2.0 -- Robust gravitational wave predictions for cosmological phase transitions
TransitionListener v2.0 supplies an end-to-end pipeline from scalar potential to gravitational wave spectra with improved handling of transition dynamics and bubble separation.
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Sensitivity of Weak Lensing Surveys to Gravitational Waves from Inspiraling Supermassive Black Hole Binaries
Weak lensing surveys cannot detect nanohertz-microhertz gravitational waves from supermassive black hole binaries under realistic conditions; only unattainable idealized surveys could probe this band.
- Exploring Leptogenesis in the Era of First Order Electroweak Phase Transition