We study second-order perturbations for a general non-canonical scalar field, minimally coupled to gravity, on the unperturbed FRW background, where metric fluctuations are neglected a priori. By employing different approaches to cosmological perturbation theory, we show that, even in this simplified set-up, the second-order perturbations to the stress tensor, the energy density and the pressure display potential instabilities, which are not present at linear order. The conditions on the Lagrangian under which these instabilities take place are provided. We also discuss briefly the significance of our analysis in light of the possible linearization instability of these fields about the FRW background.
C. Appignani, R. Casadio, S. Shankaranarayanan (2010). A note on second-order perturbations of non-canonical scalar fields. JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 03, 010-010 [10.1088/1475-7516/2010/03/010].
A note on second-order perturbations of non-canonical scalar fields
CASADIO, ROBERTO;
2010
Abstract
We study second-order perturbations for a general non-canonical scalar field, minimally coupled to gravity, on the unperturbed FRW background, where metric fluctuations are neglected a priori. By employing different approaches to cosmological perturbation theory, we show that, even in this simplified set-up, the second-order perturbations to the stress tensor, the energy density and the pressure display potential instabilities, which are not present at linear order. The conditions on the Lagrangian under which these instabilities take place are provided. We also discuss briefly the significance of our analysis in light of the possible linearization instability of these fields about the FRW background.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.