Review invited for Reports on Progress in Physics
arXiv:0801.2968v2

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MAPPING THE COSMOLOGICAL EXPANSION

Eric V. Linder


Berkeley Lab & University of California, Berkeley, CA 94720, USA evlinder@lbl.gov


Abstract. The ability to map the cosmological expansion has developed enormously, spurred by the turning point one decade ago of the discovery of cosmic acceleration. The standard model of cosmology has shifted from a matter dominated, standard gravity, decelerating expansion to the present search for the origin of acceleration in the cosmic expansion. We present a wide ranging review of the tools, challenges, and physical interpretations. The tools include direct measures of cosmic scales through Type Ia supernova luminosity distances, and angular distance scales of baryon acoustic oscillation and cosmic microwave background density perturbations, as well as indirect probes such as the effect of cosmic expansion on the growth of matter density fluctuations. Accurate mapping of the expansion requires understanding of systematic uncertainties in both the measurements and the theoretical framework, but the result will give important clues to the nature of the physics behind accelerating expansion and to the fate of the universe.


Table of Contents

INTRODUCTION
The dynamic universe
Geometry and destiny
Acceleration
Revolution in physics

EFFECTS OF ACCELERATED EXPANSION
Acceleration directly?
Kinematics
Dynamics
True acceleration?
Fate of the universe

DISTANCE MEASURES
General cosmological distance properties
Type Ia supernovae
Cosmic microwave background
Baryon acoustic oscillations
Other methods
Summary of mapping techniques

GROWTH AND EXPANSION
Growth of density perturbations
Abundance tests
Gravitational lensing
Testing gravity
First steps
Problems parametrizing beyond-Einstein gravity
Levels of discovery

SYSTEMATICS IN DATA AND THEORY
Parameterizing dark energy
Mirage of Lambda
Inhomogeneous data sets
Miscalibrated standard
Malmquist bias
Other issues

FUTURE PROSPECTS
Data and systematics
Mapping resolution
Limits on cosmic doomsday

CONCLUSIONS

REFERENCES

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