Report of the Dark Energy Task Force

Albrecht, Andreas; Hu, Wayne; Kamionkowski, Marc; Freedman, Wendy L.; Huth, J.; Suntzeff, N. B.; Staggs, Suzanne T.; Mather, John C.; Cahn, R. N.; Kolb, Edward W.; Bernstein, G. M.; Hewitt, Jacqueline N.; Knox, L.

doi:10.2172/897600

Cited by 717 publications

(1,144 citation statements)

References 36 publications

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“…The report of the Dark Energy Task Force (DETF; Albrecht et al 2006) played a critical role in systematizing the field, by categorizing experimental approaches and providing a quantitative framework to compare their capabilities. The DETF categorized then-ongoing experiments as "Stage II" (following the "Stage I" discovery experiments) and the next generation as "Stage III."…”

Section: Looking Forwardmentioning

confidence: 99%

“…9 The completion of the Astro2010 Decadal Survey and the Euclid selection by ESA make this an opportune time to review the techniques and prospects for probing cosmic acceleration with ambitious observational programs. Our goal is, in some sense, an update of the DETF report (Albrecht et al, 2006), incorporating the many developments in the field over the last few years and (the difference between a report and a review) emphasizing explanation rather than recommendation. We aim to complement other reviews of the field that differ in focus or in level of detail.…”

Section: Looking Forwardmentioning

confidence: 99%

“…Compelling detections in 2005 intensified these plans (Cole et al, 2005;Eisenstein et al, 2005), with several observational surveys proposed and numerous theoretical investigations. The rapid development of the theory led to the DETF featuring BAO as one of the four leading methods for the study of dark energy (Albrecht et al, 2006).…”

Section: The Current State Of Playmentioning

confidence: 99%

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Observational probes of cosmic acceleration

et al. 2013

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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.

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Section: Looking Forwardmentioning

confidence: 99%

Section: Looking Forwardmentioning

confidence: 99%

Section: The Current State Of Playmentioning

confidence: 99%

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Observational probes of cosmic acceleration

et al. 2013

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“…Formally elevated to the status of one of the most important problems in fundamental physics, [22] [23] uncovering the true nature of dark energy, as encapsulated in the ratio of its pressure to density, w(z) = p DE /ρ DE , has become the focus of multi-billion dollar proposed experiments using a wide variety of methods, many at redshifts above unity (see e.g. [1]). …”

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confidence: 99%

Dynamical dark energy or simply cosmic curvature?

Clarkson

Cortês

Bassett

2007

J. Cosmol. Astropart. Phys.

201

265

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We show that the assumption of a flat universe induces critically large errors in reconstructing the dark energy equation of state at z 0.9 even if the true cosmic curvature is very small, O(1%) or less. The spuriously reconstructed w(z) shows a range of unusual behaviour, including crossing of the phantom divide and mimicking of standard tracking quintessence models. For 1% curvature and ΛCDM, the error in w grows rapidly above z ∼ 0.9 reaching (50%, 100%) by redshifts of (2.5, 2.9) respectively, due to the long cosmological lever arm. Interestingly, the w(z) reconstructed from distance data and Hubble rate measurements have opposite trends due to the asymmetric influence of the curved geodesics. These results show that including curvature as a free parameter is imperative in any future analyses attempting to pin down the dynamics of dark energy, especially at moderate or high redshifts.Introduction The quest to distinguish between a cosmological constant, dynamical dark energy and modified gravity has become the dominant obsession in cosmology. Formally elevated to the status of one of the most important problems in fundamental physics, [22] [23] uncovering the true nature of dark energy, as encapsulated in the ratio of its pressure to density, w(z) = p DE /ρ DE , has become the focus of multi-billion dollar proposed experiments using a wide variety of methods, many at redshifts above unity (see e.g. [1]).Unfortunately these experiments will only measure a meagre number of w(z) parameters to any precisionperhaps two or three [3] [24] -since the standard methods all involve integrals over w(z) and typically suffer from subtle systematic effects. As a result of this information limit, studies of dark energy have traditionally fallen into two groups. The first group (see e.g. [10]) have taken their parameters to include (Ω m , Ω DE , w) with w constant and often set to −1. The 2nd group are interested in dynamical dark energy and have typically assumed Ω k = 0 for simplicity while concentrating on constraining w(z) parameters (see e.g. [11] ) [25].In retrospect, the origins of the common practise of ignoring curvature in studies of dynamical dark energy are clear. Firstly, the curved geodesics add an unwelcome complexity to the analysis that has typically been ignored in favour of studies of different parametrisations of w(z). Secondly, standard analysis of the Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAO) in the context of adiabatic ΛCDM also put stringent limits on the curvature parameter, e.g. Ω k = −0.003 ± 0.010 from WMAP + SDSS [12,13]. As a result it was taken for granted that the impact on the reconstructed w(z) would then be proportional to Ω k and hence small compared to experimental errors.Further support for the view that Ω k should not be included in studies of dark energy came from informa-

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“…57, we can create Fisher matrices spanning the parameters of complete cosmological models. In order to provide a simple statistic with which to compare experiments, The Dark Energy Task Force (DETF; Albrecht et al 2006) parametrized the equation of state w(z) of dark energy using two parameters w 0 and w a : w(z) = w 0 + z 1 + z w a .…”

Section: Fisher Methodsmentioning

confidence: 99%