Super cosmic variance from mode-coupling: A worked example

Дата и время публикации : 2013-10-21T22:03:25Z

Авторы публикации и институты :
Marilena LoVerde

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 9 pages, no figures; v2 typos corrected, references added, matches PRD accepted version
Первичная категория: astro-ph.CO

Все категории : astro-ph.CO, hep-th

Краткий обзор статьи: If the entire post-inflationary patch is large compared to our Hubble volume even a small level of non-Gaussianity can cause statistics of the primordial curvature field in our Hubble volume to be biased by mode-coupling. We explicitly compute the variation of locally measured statistics of the primordial curvature $zeta$ from non-Gaussian mode coupling within a specific inflationary scenario: the curvaton model with a quadratic curvaton potential. This "super cosmic variance" is calculated in two ways: (i) as a super observer who has access to the curvature perturbation field across the entire post-inflationary patch and therefore sees local statistics as biased by mode coupling and (ii) as a local observer who sees the statistics of $zeta$ determined by the local values of quantities in their Hubble patch. The two calculations agree and show that in the quadratic curvaton model patch-to-patch differences in statistics of $zeta$ can be interpreted entirely as a shift in the value of the curvaton field at freeze out. Applying the same arguments to single-field slow-roll inflation gives a simple picture of how non-Gaussian mode-coupling between the curvature perturbations on very different physical scales must vanish in the attractor limit.

Category: Physics