Modified Amplitude of Gravitational Waves Spectrum

TL;DR

This paper investigates how extra-dimensional effects modify the spectrum of thermal gravitational waves, showing amplitude enhancements at certain frequencies while remaining within cosmological bounds, suggesting their possible observational relevance.

Contribution

It introduces a modified spectrum of thermal gravitational waves incorporating high-frequency effects from extra dimensions, highlighting amplitude enhancement without violating cosmological constraints.

Findings

Amplitude of gravitational waves is modified in the frequency range 10^{-16} to 10^{8} Hz.

Spectral energy density remains below bounds set by nucleosynthesis.

Existence of thermal gravitational waves from extra dimensions is plausible.

Abstract

The spectrum of thermal gravitational waves is obtained by including the high frequency thermal gravitons created from extra-dimensional effect and is a new feature of the spectrum. The amplitude and spectral energy density of gravitational waves in thermal vacuum state are found enhanced. The amplitude of the waves get modified in the frequency range (10$^{-16}$ -10 $^{8}$ Hz) but the corresponding spectral energy density is less than the upper bound of various estimated results. With the addition of higher frequency thermal waves, the obtained spectral energy density of the wave in thermal vacuum state does not exceed the upper bound put by nucleosynthesis rate. The existence of cosmologically originated thermal gravitational waves due to extra dimension is not ruled out.