Deformation of Gravitational Wave Spectra from Phase Transitions During Inflation
If a first-order phase transition emits gravitational waves during cosmic inflation rather than afterward, the remaining inflationary expansion both redshifts and reshapes the spectrum, so the observed peak is not a simple redshift of the emitted peak. A general deformation function connects the present-day spectrum to the emitted one for an instant or short-lived source at any e-folding number, and applying it to a grand-unified-theory-scale transition shows the signal can be shifted into the frequency bands of ground-based or space-based detectors.
Gravitational waves of GUT phase transition during inflation Xi-He Hu1, 2, 3, ∗and Ye-Ling Zhou1, †
This paper studies the gravitational-wave (GW) signal produced if a first-order grand-unified-theory (GUT) phase transition occurs during cosmic inflation rather than afterward. The authors derive a …