Axion-like fields coupled to the Nieh-Yan term generate a chiral GW background during radiation domination, with parameter space explored for detectability in PTA and space-based observatories.
Gravitational waves from binary supermassive black holes missing in pulsar observations
6 Pith papers cite this work. Polarity classification is still indexing.
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abstract
Gravitational waves are expected to be radiated by supermassive black hole binaries formed during galaxy mergers. A stochastic superposition of gravitational waves from all such binary systems will modulate the arrival times of pulses from radio pulsars. Using observations of millisecond pulsars obtained with the Parkes radio telescope, we constrain the characteristic amplitude of this background, $A_{\rm c,yr}$, to be < $1.0\times10^{-15}$ with 95% confidence. This limit excludes predicted ranges for $A_{\rm c,yr}$ from current models with 91-99.7% probability. We conclude that binary evolution is either stalled or dramatically accelerated by galactic-center environments, and that higher-cadence and shorter-wavelength observations would result in an increased sensitivity to gravitational waves.
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Defines peak-integrated sensitivity curves (PISCs) that fold in the expected spectral shape of gravitational waves from cosmological phase transitions and supplies semianalytical fits plus public data for major detectors.
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.
Kaniadakis entropic cosmology modifies early-universe dynamics and is constrained by its predictions for Starobinsky inflation and the primordial tensor spectrum using current CMB and gravitational-wave observations.
F-term hybrid inflation with SU(1,1)/U(1) or SU(2)/U(1) Kähler geometry in GUTs can be realized without inflationary extrema for broad parameters, matching ACT/SPT data via curvature and tadpole adjustments while predicting cosmic string gravitational waves.
A review that unifies analytical expressions for scalar-induced gravitational waves and emphasizes calculations for non-radiation-dominated cosmologies.
citing papers explorer
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Chiral Gravitational Wave Background from Audible Axion via Nieh-Yan Term
Axion-like fields coupled to the Nieh-Yan term generate a chiral GW background during radiation domination, with parameter space explored for detectability in PTA and space-based observatories.
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New Sensitivity Curves for Gravitational-Wave Signals from Cosmological Phase Transitions
Defines peak-integrated sensitivity curves (PISCs) that fold in the expected spectral shape of gravitational waves from cosmological phase transitions and supplies semianalytical fits plus public data for major detectors.
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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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Constraints on Kaniadakis Cosmology from Starobinsky Inflation and Primordial Tensor Perturbations
Kaniadakis entropic cosmology modifies early-universe dynamics and is constrained by its predictions for Starobinsky inflation and the primordial tensor spectrum using current CMB and gravitational-wave observations.
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F-Term Hybrid Inflation with T-Model K\"ahler Geometry and Beyond
F-term hybrid inflation with SU(1,1)/U(1) or SU(2)/U(1) Kähler geometry in GUTs can be realized without inflationary extrema for broad parameters, matching ACT/SPT data via curvature and tadpole adjustments while predicting cosmic string gravitational waves.
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Scalar induced gravitational waves review
A review that unifies analytical expressions for scalar-induced gravitational waves and emphasizes calculations for non-radiation-dominated cosmologies.