Astrophysical tests of modified gravity: the morphology and kinematics of dwarf galaxies

Vikram, V.; Cabré, Anna; Jain, Bhuvnesh; Vanderplas, Jake

doi:10.1088/1475-7516/2013/08/020

Cited by 66 publications

(89 citation statements)

References 45 publications

(110 reference statements)

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“…Taken together, the added screening effects from the environment likely weakens solar system constraints by a factor of a few [322]. These constraints are an order of magnitude weaker for these models than constraints coming from Cehpheid variables and dwarf galaxies [859,860].…”

Section: Laboratory and Solar System Tests Of Chameleon Theoriesmentioning

confidence: 93%

“…Additionally, the external fifth force on a dwarf galaxy can result in a segregation of the the stars, giant stars and gas along the direction of the external force. For unscreened disk galaxies, this also leads to a warping of the shape of the stellar disk [860]. The difference in forces felt by compact objects can lead to the displacement of supermassive black holes in Vainshtein theories, which is discussed in the following subsection.…”

Section: Galaxies In the Nearby Universementioning

confidence: 95%

“…Scalar radiation must be accounted for in future high precision tests that use stellar pulsations or explosions, and may also provide additional tests [894]. Figure 13: Limits on chameleon theories coming from astrophysical [322,859,860] and cosmological [340,895,896] probes. The x-axis gives the range of length scales probed by particular experiments.…”

Section: Pulsating Stars and The Distance Laddermentioning

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: Laboratory and Solar System Tests Of Chameleon Theoriesmentioning

confidence: 93%

Section: Galaxies In the Nearby Universementioning

confidence: 95%

Section: Pulsating Stars and The Distance Laddermentioning

confidence: 99%

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Beyond the cosmological standard model

et al. 2015

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“…Chameleon and chameleon-like theories [242,243,244,245] (which include f (R) models [246]) screen by using non-linearities in the field equations to suppress the scalar charge. As a result, these theories do not satisfy the equivalence principle [247], a fact that has been exploited by many proposed tests [248,249,250,251,252,253,254,255,256].…”

Section: Gravity In Cosmologymentioning

confidence: 99%

BeyondΛCDM: Problems, solutions, and the road ahead

Bull

Akrami

Adamek

et al. 2016

Physics of the Dark Universe

420

210

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Despite its continued observational successes, there is a persistent (and growing) interest in extending cosmology beyond the standard model, ΛCDM. This is motivated by a range of apparently serious theoretical issues, involving such questions as the cosmological constant problem, the particle nature of dark matter, the validity of general relativity on large scales, the existence of anomalies in the CMB and on small scales, and the predictivity and testability of the inflationary paradigm. In this paper, we summarize the current status of ΛCDM as a physical theory, and review investigations into possible alternatives along a number of different lines, with a particular focus on highlighting the most promising directions. While the fundamental problems are proving reluctant to yield, the study of alternative cosmologies has led to considerable progress, with much more to come if hopes about forthcoming high-precision observations and new theoretical ideas are fulfilled.Keywords: cosmology -dark energy -cosmological constant problem -modified gravitydark matter -early universe Cosmology has been both blessed and cursed by the establishment of a standard model: ΛCDM. On the one hand, the model has turned out to be extremely predictive, explanatory, and observationally robust, providing us with a substantial understanding of the formation of large-scale structure, the state of the early Universe, and the cosmic abundance of different types of matter and energy. It has also survived an impressive battery of precision observational tests -anomalies are few and far between, and their significance is contentious where they do arise -and its predictions are continually being vindicated through the discovery of new effects (B-mode polarization [1] and lensing [2,3] of the cosmic microwave background (CMB), and the kinetic Sunyaev-Zel'dovich effect [4] being some recent examples). These are the hallmarks of a good and valuable physical theory.On the other hand, the model suffers from profound theoretical difficulties. The two largest contributions to the energy content at late times -cold dark matter (CDM) and the cosmological constant (Λ) -have entirely mysterious physical origins. CDM has so far evaded direct detection by laboratory experiments, and so the particle field responsible for it -presumably a manifestation of "beyond the standard model" particle physics -is unknown. Curious discrepancies also appear to exist between the predicted clustering properties of CDM on small scales and observations. The cosmological constant is even more puzzling, giving rise to quite simply the biggest problem in all of fundamental physics: the question of why Λ appears to take such an unnatural value [5,6,7]. Inflation, the theory of the very early Universe, has also been criticized for being fine-tuned and under-predictive [8], and appears to leave many problems either unsolved or fundamentally unresolvable. These problems are indicative of a crisis.From January 14th-17th 2015, we held a conference in Oslo, Norway to surve...

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“…Only low-density components like the gaseous disk and low-mass stars, in unscreened haloes, are unscreened. This picture of partially screened galaxy opens a novel opportunity to test fðRÞ gravity by examining the different dynamics between their screened and unscreened components [45].…”

Section: Summary and Discussionmentioning

confidence: 99%

Revisiting the screening mechanism inf(R)gravity

Hawken

et al. 2014

Phys. Rev. D

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We reexamine the screening mechanism in fðRÞ gravity using N-body simulations. By explicitly examining the relation between the extrascalar field δf R and the gravitational potential ϕ in the perturbed Universe, we find that the relation between these two fields plays an important role in understanding the screening mechanism. We show that the screening mechanism in fðRÞ gravity depends mainly on the depth of the potential well and find a useful condition for identifying unscreened haloes in simulations. We also discuss the potential application of our results to real galaxy surveys.

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Astrophysical tests of modified gravity: the morphology and kinematics of dwarf galaxies

Cited by 66 publications

References 45 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

BeyondΛCDM: Problems, solutions, and the road ahead

Revisiting the screening mechanism inf(R)gravity

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