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Detection limits for super-Hubble suppression of causal fluctuations

Research output: Contribution to journalArticle

Original languageEnglish
Article number123513
Pages (from-to)1-7
Number of pages7
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number12
Publication statusPublished - 15 Dec 2000


We investigate to what extent future microwave background experiments might be able to detect a suppression of fluctuation power on large scales in flat and open universe models. Such suppression would arise if fluctuations are generated by causal processes, and a measurement of a small suppression scale would be problematic for inflation models, but consistent with many defect models. More speculatively, a measurement of a suppression scale of the order of the present Bubble radius could provide independent evidence for a fine-tuned inflation model leading to a low-density universe. We find that, depending on the primordial power spectrum, a suppression scale modestly larger than the visible Horizon can be detected, but that the detectability drops very rapidly with increasing scale. For models with two periods of inflation, there is essentially no possibility of detecting a causal suppression scale.

ID: 21743105