Abstract
So far there is only indirect evidence that the Universe is undergoing an accelerated expansion. The evidence for cosmic acceleration is based on the observation of different objects at different distances and requires invoking the Copernican cosmological principle and Einstein’s equations of motion. We examine the direct observability using recession velocity drifts (Sandage-Loeb effect) of 21-cm hydrogen absorption systems in upcoming radio surveys. This measures the change in velocity of the same objects separated by a time interval and is a model-independent measure of acceleration. We forecast that for a CHIME-like survey with a decade time span, we can detect the acceleration of a universe with confidence. This acceleration test requires modest data analysis and storage changes from the normal processing and cannot be recovered retroactively.
- Received 11 November 2013
DOI:https://doi.org/10.1103/PhysRevLett.113.041303
© 2014 American Physical Society
Synopsis
Direct Test of Cosmic Acceleration
Published 24 July 2014
Future radio surveys of intergalactic hydrogen clouds could offer the first direct measurement of the Universe’s acceleration.
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