Supernova Limits on the Cosmic Equation of State

Garnavich, P.; Jha, Saurabh W.; Challis, Peter; Clocchiatti, A.; Diercks, A.; Filippenko, A. V.; Gilliland, R. L.; Hogan, Craig J.; Kirshner, R.; Leibundgut, B.; Phillips, M. M.; Reiss, David J; Riess, Adam G.; Schmidt, B. P.; Schommer, R. A.; Smith, R. C.; Spyromilio, J.; Stubbs, C. W.; Suntzeff, Nicholas B.; Tonry, J.; Carroll, Sean M.

doi:10.1086/306495

Cited by 774 publications

(545 citation statements)

References 49 publications

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“…There is overwhelming observational evidence that the universe is undergoing accelerated expansion from observations of type Ia supernovae [1][2][3][4][5][6][7][8][9][10][11][12], from Cosmic Microwave Background measurements [13][14][15][16][17][18][19][20][21][22], and from detailed studies of large-scale structure [23][24][25][26][27][28][29][30]. All of the measurements are in good agreement, with all data consistent with a Λ-cold dark matter (ΛCDM) cosmology [31,32], with a value of the cosmological constant of about Λ obs.…”

Section: Introduction 1 the Cosmological Constant And Its Discontentsmentioning

confidence: 99%

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Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Section: Introduction 1 the Cosmological Constant And Its Discontentsmentioning

confidence: 99%

“…All of the measurements are in good agreement, with all data consistent with a Λ-cold dark matter (ΛCDM) cosmology [31,32], with a value of the cosmological constant of about Λ obs. ∼ (10 −3 eV) 4 .…”

Section: Introduction 1 the Cosmological Constant And Its Discontentsmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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“…We further take the universe to be flat, i.e., k = 0. This is justified in light of recent measurements [90][91][92]. The Friedmann-Robertson-Walker (FRW) line element has the conventional form:…”

Section: Varying Couplings and The Smementioning

confidence: 81%

The Lorentz-Violating Extension of the Standard Model

Lehnert

2004

Beyond the Desert 2003

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Abstract. Quantum-gravity effects are expected to be suppressed by the Planck mass. For experimental progress it is therefore important to identify potential signatures from Planck-scale physics that are amenable to ultrahigh-precision tests. It is argued that minuscule violations of Lorentz and CPT symmetry are candidate signals. In addition, theoretical and experimental aspects of the Standard-Model Extension, which describes the emergent low-energy effects, are discussed. MotivationAn important open question in our understanding of nature at its fundamental level concerns a unified quantum description of all fundamental interactions including gravity. Such a theory is likely to become dominant only as the Planck scale is approached, so that quantum-gravity effects are expected to be minuscule at presently attainable energies. Moreover, the absence of a fully realistic and viable candidate underlying theory provides a major obstacle for the identification of concrete quantum-gravity signatures that can be searched for in present-day or near-future experiments.A possible approach to overcome this phenomenological issue is to determine exact relations in the currently accepted laws of physics that may be violated in prospective fundamental theories and that can be tested with ultrahighprecision. Symmetries typically satisfy these criteria. For example, Lorentz and CPT invariance are cornerstones of our present understanding of nature at the fundamental level, and a variety of Lorentz and CPT tests belong to the most sensitive null experiments available. Lorentz and CPT violation is also a key feature of certain approaches to underlying physics.For example, couplings varying on cosmological scales are one possible source of Lorentz and CPT violation [1]. This fact does not come as a surprise: parameters dependent on spacetime break translational invariance, and translations, rotations, and boosts are linked in the Poincaré group. Thus, violations of translation symmetry can also affect Lorentz invariance. This can be understood intuitively as follows. The equations of motion typically contain the gradient of the coupling, which selects a preferred direction in spacetime leading to apparent Lorentz violation.In this talk, we discuss some theoretical and experimental aspects of the Standard-Model Extension (SME) [2][3][4][5][6][7], which is the low-energy framework for Lorentz-breaking effects. The SME is a dynamical model constructed to contain all Lorentz-and CPT-violating lagrangian terms consistent with coordinate

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“…This has been treated in great detail by the research groups who discovered the acceleration Garnavich et al 1998 ;Riess et al 1999Riess et al , 2001), and we shall therefore not discuss these tests here.…”

Section: Changes In Observable Properties At the Present Epochmentioning

confidence: 99%

“…Two independent research groups using Type Ia supernovae as standard candles have discovered signs of a small positive cosmological constant in the Hubble diagram Garnavich et al 1998 ;Riess et al 1999Riess et al , 2001. Further evidence comes from investigations of anisotropies in the cosmic microwave background as well as large-scale structure and the age of the universe (for recent reviews and references see Carroll 2001, Sahni & Starobinsky 2000, and Bahcall et al 1999.…”

Section: Introductionmentioning

confidence: 99%

Untitled

2002

ApJ

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We consider ever-expanding big bang models with a cosmological constant, ", and investigate in detail the evolution of the observable part of the universe. We also discuss quintessence models from the same point of view. A new concept, the "-sphere (or Q-sphere, in the case of quintessence) is introduced. This is the surface in our visible universe that bounds the region where dark energy dominates the expansion, and within which the universe is accelerating. We follow the evolution of this surface as the universe expands, and we also investigate the evolution of the particle and event horizons as well as the Hubble surface. We calculate the extent of the observable universe and the portion of it that can be seen at di †erent epochs. Furthermore, we trace the changes in redshift, apparent magnitude and apparent size of distant sources through cosmic history. Our approach is di †erent from, but complementary to, most other contemporary investigations, which concentrate on the past light cone at the present epoch. When presenting numerical results we use the FRW world model with and as our stan-) m0 \ 0.30 ) "0 \ 0.70 dard cosmological model. In this model the "-sphere is at a redshift of 0.67, and within a few Hubble times the event horizon will be stationary at a Ðxed proper distance of 5.1 Gpc (assuming All h 0 \ 0.7). cosmological sources with present redshift larger than 1.7 have by now crossed the event horizon and are therefore completely out of causal contact.

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Supernova Limits on the Cosmic Equation of State

Cited by 774 publications

References 49 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

The Lorentz-Violating Extension of the Standard Model

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