Webinar: Gravitational wave background from Standard Model physics

por Mikko Laine (Bern University)

martes 9 jun. 2015 15:00 → 16:00 Europe/Madrid

retransmitted from the Seminar Room, 1.1.1 (IFIC)

Apart from CMB photons and neutrinos, another principal carrier of information from very early epochs in the history of the universe are gravitational waves. Besides inflation, they have been proposed to contain features originating from post-inflationary phenomena such as preheating or thermal phase transitions. However, a gravitational wave background, akin to blackbody radiation, is also being emitted from a plasma without any phase transition. In this talk the general properties of the thermal background are discussed. The absence of additional relativistic degrees of freedom in Planck data sets an upper bound on the total energy density carried by gravitational waves and thereby on the highest temperature of the radiation epoch. Theoretically it might even be possible to observe the thermal background with future generations of GHz range detectors.