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Published September 10, 2013 | public
Journal Article

Observational probes of cosmic acceleration

Abstract

The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock–Paczynski effect, and direct measurements of the Hubble constant H_0. We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever larger scales.

Additional Information

© 2013 Elsevier B.V. Accepted 6 May 2013; Available online 13 May 2013; editor: M.P. Kamionkowski. We gratefully acknowledge the many mentors, collaborators, and students with whom we have learned this subject over the years. For valuable comments and suggestions on the draft manuscript, we thank Joshua Frieman, Dragan Huterer, Chris Kochanek, Andrey Kravtsov, Mark Sullivan, and Alexey Vikhlinin. We also thank the many readers who sent comments in response to the original arXiv posting of the article, which led to numerous improvements in the text and referencing. We gratefully acknowledge support from the National Science Foundation, the National Aeronautics and Space Administration, the Department of Energy Office of Science, including NSF grants AST-0707725, AST-0707985, AST-0807337, and AST-1009505, NASA grant NNX07AH11G1320, and DOE grants DE-FG03-02-ER40701 and DE-SC0006624. DW acknowledges the hospitality of the Institute for Advanced Study and the support of an AMIAS membership during critical phases of this work. MM was supported by the Center for Cosmology and Astro-Particle Physics (CCAPP) at Ohio State University. CH acknowledges additional support from the Alfred P. Sloan Foundation and the David & Lucile Packard Foundation. ER was supported by the NASA Einstein Fellowship Program, grant PF9-00068.

Additional details

Created:
August 19, 2023
Modified:
October 25, 2023