Log-periodic stochastic gravitational-wave background beyond Einstein gravity

Gianluca Calcagni, Sachiko Kuroyanagi
General Relativity and Quantum Cosmology, General Relativity and Quantum Cosmology (gr-qc), Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Theory (hep-th)
ET-0274A-23, IFT-UAM/CSIC-23-105
2023-08-10 16:00:00
Periodic patterns of logarithmic oscillations can arise in primordial curvature perturbation spectra and in the associated stochastic gravitational-wave background via different mechanisms. We show that, in the presence of log oscillations, the spectral shape of the stochastic background has a unique parametrization independent of its physical origin. We also show that this log-periodic modulation can be generated in any scenario beyond Einstein gravity endowed with an approximate discrete scale invariance, a symmetry typical of deterministic fractal spacetimes that could emerge in quantum gravity under certain conditions. We discuss how a log-oscillatory spectral shape arises from concrete inflationary models beyond Einstein gravity and the prospects for detection in Einstein Telescope and other next-generation gravitational-wave observatories. We find that these instruments will be sensitive to log-periodic features if the detection is made with a high signal-to-noise ratio (SNR) and that the error scales as $1/{\rm SNR}$.
PDF: Log-periodic stochastic gravitational-wave background beyond Einstein gravity.pdf
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