Phantom dark energy from non-local massive gravity

Дата и время публикации : 2013-07-15T11:31:24Z

Авторы публикации и институты :
Michele Maggiore

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 5 pages, 2 figures
Первичная категория: hep-th

Все категории : hep-th, astro-ph.CO, gr-qc, hep-ph

Краткий обзор статьи: We discuss the cosmological consequences of a model based on a non-local infrared modification of Einstein equations. We find that the model generates a dynamical dark energy that can account for the presently observed value of the dark energy density, without introducing a cosmological constant. Tuning a free mass parameter $m$ to a value $m= 0.67 H_0$ we reproduce the observed value $Omega_{rm DE}simeq 0.68$. This leaves us with no free parameter and we then get a pure prediction for the EOS parameter of dark energy. Writing $w_{rm DE}(a)=w_0+(1-a) w_a$, we find $w_0simeq-1.04$ and $w_asimeq -0.02$, consistent with the Planck data, and on the phantom side. We also argue that non-local equations of the type that we propose must be understood as purely classical effective equations, such as those derived in semiclassical gravity for the in-in matrix elements of the metric. As such, any apparent ghost instability in such equations only affects the classical dynamics, but there is no propagating degree of freedom associated to the ghost, and no issue of ghost-induced quantum vacuum decay.

Category: Physics