Model-independent tests of cosmic gravity

Gravitation governs the expansion and fate of the universe, and the growth of large-scale structure within it, but has not been tested in detail on these cosmic scales. The observed acceleration of the expansion may provide signs of gravitational laws beyond general relativity (GR). Since the form of any such extension is not clear, from either theory or data, we adopt a model-independent approach to parametrizing deviations to the Einstein framework. We explore the phase space dynamics of two key post-GR functions and derive a classification scheme, and an absolute criterion on accuracy necessary for distinguishing classes of gravity models. Future surveys will be able to constrain the post-GR functions' amplitudes and forms to the required precision, and hence reveal new aspects of gravitation.

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Cosmological Tests of Gravity

Annual Review of Astronomy and Astrophysics ◽

10.1146/annurev-astro-091918-104423 ◽

2019 ◽

Vol 57 (1) ◽

pp. 335-374 ◽

Cited By ~ 19

Author(s):

Pedro G. Ferreira

Keyword(s):

General Relativity ◽

Large Scale ◽

Large Scale Structure ◽

Scale Structure ◽

Alternative Theories Of Gravity ◽

Systematic Uncertainties ◽

Cosmological Observations ◽

Theories Of Gravity ◽

Tests Of Gravity ◽

The Universe

Cosmological observations are beginning to reach a level of precision that allows us to test some of the most fundamental assumptions in our working model of the Universe. One such assumption is that gravity is governed by the theory of general relativity. In this review, we discuss how one might go about extending general relativity and how such extensions can be described in a unified way on large scales. This allows us to describe the phenomenology of modified gravity in the growth and morphology of the large-scale structure of the Universe. On smaller scales, we explore the physics of gravitational screening and how it might manifest itself in galaxies, clusters, and, more generally, in the cosmic web. We then analyze the current constraints from large-scale structure and conclude by discussing the future prospects of the field in light of the plethora of surveys currently being planned. Key results include the following: ▪ There are a plethora of alternative theories of gravity that are restricted by fundamental physics considerations. ▪ There is now a well-established formalism for describing cosmological perturbations in the linear regime for general theories of gravity. ▪ Gravitational screening can mask modifications to general relativity on small scales but may, itself, lead to distinctive signatures in the large-scale structure of the Universe. ▪ Current constraints on both linear and nonlinear scales may be affected by systematic uncertainties that limit our ability to rule out alternatives to general relativity. ▪ The next generation of cosmological surveys will dramatically improve constraints on general relativity, by up to two orders of magnitude.

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A new golden age: testing general relativity with cosmology

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2011.0366 ◽

2011 ◽

Vol 369 (1957) ◽

pp. 4941-4946

Author(s):

Rachel Bean ◽

Pedro G. Ferreira ◽

Andy Taylor

Keyword(s):

General Relativity ◽

Large Scale ◽

Large Scale Structure ◽

Einstein Gravity ◽

Field Equations ◽

The Past ◽

Cosmological Observations ◽

Wide Range ◽

Theories Of Gravity ◽

The Universe

Gravity drives the evolution of the Universe and is at the heart of its complexity. Einstein's field equations can be used to work out the detailed dynamics of space and time and to calculate the emergence of large-scale structure in the distribution of galaxies and radiation. Over the past few years, it has become clear that cosmological observations can be used not only to constrain different world models within the context of Einstein gravity but also to constrain the theory of gravity itself. In this article, we look at different aspects of this new field in which cosmology is used to test theories of gravity with a wide range of observations.

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Testing general relativity: from local to cosmological scales

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2011.0293 ◽

2011 ◽

Vol 369 (1957) ◽

pp. 5042-5057 ◽

Cited By ~ 3

Author(s):

Jean-Philippe Uzan

Keyword(s):

General Relativity ◽

Large Scale ◽

Large Scale Structure ◽

Scale Structure ◽

Geometric Structures ◽

Tests Of General Relativity ◽

The Universe

I summarize various tests of general relativity on astrophysical scales, based on the large-scale structure of the universe but also on other systems, in particular the constants of physics. I emphasize the importance of hypotheses on the geometric structures of our universe while performing such tests and discuss their complementarity as well as their possible extensions.

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Homogeneity and Clustering

The Large-Scale Structure of the Universe ◽

10.23943/princeton/9780691209838.003.0001 ◽

2020 ◽

pp. 3-36

Author(s):

P. J. E. Peebles

Keyword(s):

General Relativity ◽

Large Scale ◽

Albert Einstein ◽

Large Scale Structure ◽

Relativity Theory ◽

Expanding Universe ◽

History Of ◽

Edwin Hubble ◽

The Universe ◽

Georges Lemaître

This chapter traces the history of the development of ideas on the large-scale structure of the universe. Modern discussions of the nature of the large-scale matter distribution can be traced back to three central ideas. In 1917, Albert Einstein argued that a closed homogeneous world model fits very well into general relativity theory and the requirements of Mach's principle. In 1926, Edwin Hubble showed that the large-scale distribution of galaxies is close to uniform with no indication of an edge or boundary. In 1927, Georges Lemaître showed that the uniform distribution of galaxies fits very well with the pattern of galaxy redshifts. The chapter then assesses several questions. The first is whether the universe really is homogeneous. Could the homogeneity of the universe have been deduced ahead of time from general principles? Or might it be a useful guide to new principles? It also asks how clustering evolves in an expanding universe, what its origin is, and what this reveals about the nature of the universe.

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Principles of Physical Cosmology

10.23943/princeton/9780691209814.001.0001 ◽

2020 ◽

Author(s):

P. J. E. Peebles

Keyword(s):

General Relativity ◽

Large Scale ◽

Large Scale Structure ◽

Critical Area ◽

Nobel Lecture ◽

Modern Physics ◽

History Of ◽

Cosmological Tests ◽

Physical Cosmology ◽

The Universe

This book is the essential introduction to this critical area of modern physics, written by a leading pioneer who has shaped the course of the field for decades. The book provides an authoritative overview of the field, showing how observation has combined with theory to establish the science of physical cosmology. The book presents the elements of physical cosmology, including the history of the discovery of the expanding universe; surveys the cosmological tests that measure the geometry of space-time, with a discussion of general relativity as the basis for these tests; and reviews the origin of galaxies and the large-scale structure of the universe. Now featuring the author's 2019 Nobel lecture, the book remains an indispensable reference for students and researchers alike.

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