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.

On the recovery of ISW fluctuations using large-scale structure tracers and CMB temperature and polarization anisotropies

“…Measurements of the cosmic microwave background (CMB), galaxy clusters, Type Ia supernovae or baryonic acoustic oscillations (BAOs) indicate an accelerated expansion of the Universe (see Weinberg et al 2013, for a review) caused by the dark energy (Peebles & Ratra 2003). The essence of dark energy is one of the most intriguing problems in modern cosmology.…”

Arbitrary scalar-field and quintessence cosmological models

“…In order to obtain a deeper physical understanding of the solutions a comparison with the supernovae data is necessary [44]. In addition to this, in order to compare the obtained models with the data on the microwave background cosmic radiation and the large scale structure of the Universe, the study of the cosmological perturbations of the solutions is necessary in the obtained theoretical framework.…”

“…CDM contributes m ∼ 0.3 [41], and it is mainly motivated by the theoretical interpretation of the galactic rotation curves and large scale structure formation. DE is assumed to provide us with DE ∼ 0.7, and it is responsible for the acceleration of the distant type Ia supernovae [44]. There are a huge number of proposed candidates for DE (see, for instance, [45,46]).…”

Cosmic Structure Probes of the Dark Universe (Porting and Tuning HACC on Mira): ALCF-2 Early Science Program Technical Report

“…As the quantity and quality of observational data increases, corresponding increases in our simulation ability are required. In order to tackle questions related to the detailed behavior of dark matter and dark energy, the two dominate, yet mysterious, components of the energy-density of the universe [2,1], we must be able to simulate the effect of small changes in theory parameters on observable statistical quantities.…”

“…At scales larger than that of galaxy clusters, no other forces make a significant contribution 1 . As a result, we can accurately predict how the matter will move and cluster at large scales using a "gravity-only" simulation.…”