Thermal gravitational waves

TL;DR

This paper reviews potential high-frequency thermal gravitational wave sources from astrophysical objects and early universe conditions, estimating their fluxes and discussing detection methods for such radiation.

Contribution

It provides a comparative analysis of thermal gravitational wave emissions from various astrophysical and cosmological sources, including estimates of their fluxes and detection strategies.

Findings

High frequency thermal gravitational waves can originate from neutron stars, white dwarfs, gamma-ray bursts, and evaporating black holes.

The background flux of thermal gravitational waves from the early universe is estimated.

Detection schemes for high frequency thermal gravitational radiation are discussed.

Abstract

There is a lot of current interest in sources of gravitational waves and active ongoing projects to detect such radiation, such as the LIGO project. These are long wavelength, low frequency gravitational waves. LISA would be sensitive to much longer wavelengths and lower fluxes. However compact stellar objects can generate high frequency thermal gravitational radiation, which in the case of hot neutron stars can be high. Also white dwarfs and main-sequence stars can generate such radiation from plasma-Coulomb collisions. Again gamma ray bursts and relativistic jets could also be sources of such radiation. Terminal stages of evaporating black holes could also generate high frequency gravitational radiation. A comparative study is made of the thermal gravitational wave emission from all of the above sources, and the background flux is estimated. The earliest phases of the universe close to the Planck scale would also leave remnant thermal gravitational waves. The integrated thermal gravitational flux as the universe expands is also estimated and compared with that from all the discrete sources discussed above. Possible schemes to detect such sources of high frequency thermal gravitational radiation are discussed and the physical principles involved are elaborated.