Scale-invariant fluctuations from Galilean genesis

Wang, Yi; Brandenberger, Robert H.

doi:10.1088/1475-7516/2012/10/021

Cited by 37 publications

(36 citation statements)

References 33 publications

(53 reference statements)

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“…The galileons have been used to address cosmic acceleration [516][517][518][519][520][521][522][523][524][525] and the origin of density perturbations in the early universe through inflation [526][527][528][529][530][531][532][533][534][535][536] and inflationary alternatives [537][538][539][540][541][542][543][544][545]. They have also been used to violate the null energy condition [537,[544][545][546][547][548][549][550][551][552][553].…”

Section: The Vainshtein Mechanism: Galileonsmentioning

confidence: 99%

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: The Vainshtein Mechanism: Galileonsmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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“…[18]. The interesting feature of Galileons to allow self-accelerating de Sitter solutions while providing a ghost-free theory [16,19] has generated a flurry of investigations, targeted at cosmological models and their observational signatures [20][21][22][23][24][25][26][27][28], inflationary JHEP07(2013)067 models [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45], gravitational lensing [46], spherically symmetric solutions in the vicinity of compact sources [47], Binary Pulsars [48][49][50], etc. .…”

Section: Jhep07(2013)067mentioning

confidence: 99%

Superluminality in the Bi- and Multi-Galileon

Fromont

Rham

Heisenberg

et al. 2013

J. High Energ. Phys.

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We re-explore the Bi-and Multi-Galileon models with trivial asymptotic conditions at infinity and show that propagation of superluminal fluctuations is a common and unavoidable feature of these theories, unlike previously claimed in the literature. We show that all Multi-Galileon theories containing a Cubic Galileon term exhibit superluminalities at large distances from a point source, and that even if the Cubic Galileon is not present one can always find sensible matter distributions in which there are superluminal modes at large distances. In the Bi-Galileon case we explicitly show that there are always superluminal modes around a point source even if the Cubic Galileon is not present. Finally, we briefly comment on the possibility of avoiding superluminalities by modifying the asymptotic conditions at infinity.

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“…3). Alternatively, f g (z)G(z)P 1/2 0 /s 4 provides a powerful test of gravity, as dark energy and modified gravity models that give identical H(z) likely give different f g (z) (Wang 2008a). Measuring {x h (z), x d (z), f g (z)G(z)P 1/2 0 /s 4 } simultaneously allows us to probe gravity without fixing the background cosmological model.…”

Section: S U M M a Ry A N D Discussionmentioning

confidence: 99%

“…We use the Fisher matrix formalism to study the parameter estimation using galaxy clustering data (Tegmark 1997;Seo & Eisenstein 2003), based on the approach developed in Wang (2006Wang ( , 2008aWang ( , 2010a and Wang et al (2010). In the limit where the length scale corresponding to the survey volume is much larger than the scale of any features in the observed galaxy power spectrum P g (k), we can assume that the likelihood function for the band powers of a galaxy redshift survey is Gaussian (Feldman, Kaiser & Peacock Y. Wang 1994), with a measurement error in ln P (k) that is proportional to [V eff (k)] −1/2 , with the effective volume of the survey defined as V eff (k, μ) ≡ dr 3 n(r)P g (k, μ) n(r)P g (k, μ) + 1 2 = nP g (k, μ) nP g (k, μ) + 1…”

Section: E T H O D O L O G Y 21 the Fisher Matrix Formalismmentioning

confidence: 99%

Robust constraints on dark energy and gravity from galaxy clustering data

Wang¹

2012

Monthly Notices of the Royal Astronomical Society

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Galaxy clustering data provide a powerful probe of dark energy. We examine how the constraints on the scaled expansion history of the Universe, xh(z) =H(z)s (with s denoting the sound horizon at the drag epoch), and the scaled angular diameter distance, xd(z) =DA(z)/s, depend on the methods used to analyse the galaxy clustering data. We find that using the observed galaxy power spectrum, Pobsg(k), xh(z) and xd(z) are measured more accurately and are significantly less correlated with each other, compared to using only the information from the baryon acoustic oscillations (BAO) in Pobsg(k). Using the {xh(z), xd(z)} from Pobsg(k) gives a Dark Energy Task Force (DETF) dark energy figure of merit (FoM) approximately a factor of 2 larger than using the {xh(z), xd(z)} from BAO only; this provides a robust conservative method to go beyond BAO only in extracting dark energy information from galaxy clustering data. We find that a Stage IV galaxy redshift survey, with 0.7 < z < 2 over 15 000 (deg)2, can measure with high precision [where fg(z) and G(z) are the linear growth rate and factor of large‐scale structure, respectively, and is the dimensionless normalization of Pobsg(k)], when redshift‐space distortion information is included. The measurement of provides a powerful test of gravity, and significantly boosts the dark energy FoM when general relativity is assumed.

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Scale-invariant fluctuations from Galilean genesis

Cited by 37 publications

References 33 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

Superluminality in the Bi- and Multi-Galileon

Robust constraints on dark energy and gravity from galaxy clustering data

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