Gravitational wave background from Standard Model physics: qualitative features
- Institute for Theoretical Physics, Albert Einstein Center, University of Bern,Sidlerstrasse 5, CH-3012 Bern (Switzerland)
Because of physical processes ranging from microscopic particle collisions to macroscopic hydrodynamic fluctuations, any plasma in thermal equilibrium emits gravitational waves. For the largest wavelengths the emission rate is proportional to the shear viscosity of the plasma. In the Standard Model at T>160 GeV, the shear viscosity is dominated by the most weakly interacting particles, right-handed leptons, and is relatively large. We estimate the order of magnitude of the corresponding spectrum of gravitational waves. Even though at small frequencies (corresponding to the sub-Hz range relevant for planned observatories such as eLISA) this background is tiny compared with that from non-equilibrium sources, the total energy carried by the high-frequency part of the spectrum is non-negligible if the production continues for a long time. We suggest that this may constrain (weakly) the highest temperature of the radiation epoch. Observing the high-frequency part directly sets a very ambitious goal for future generations of GHz-range detectors.
- Sponsoring Organization:
- SCOAP3, CERN, Geneva (Switzerland)
- OSTI ID:
- 22454570
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2015, Issue 07; Other Information: PUBLISHER-ID: JCAP07(2015)022; OAI: oai:repo.scoap3.org:11110; Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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