Seminar

Late-time quantum backreaction in cosmology

By
Drazen Glavan (Utrecht University)
Date
Place
Aula 507
seminar ICCUB
Quantum fluctuations of the matter field contribute to its energy-momentum tensor. This contribution (backreaction) should source the Einstein equations. For fields living on time-dependent backgrounds, such as FLRW, this contribution to the energy-momentum tensor can exhibit secular behavior - its magnitude can grow in time. Given enough time, in certain cases, it can grow large enough to considerably alter the classical dynamics of the expansion of the Universe. I will present a model of a non-minimally coupled massless (and massive) scalar field whose inflationary quantum fluctuations are evolved throughout the history of the Universe, from inflation to radiation and matter dominated eras. The energy-momentum tensor of these fluctuations is calculated in each era. For certain range of non-minimal coupling the backreaction remains small throughout the history and in late matter era exhibits interesting transient phenomena where it grows large and could affect the expansion considerably, similar to the effect of Dark Energy.