scholarly journals Testing general relativity and alternative theories of gravity with space-based atomic clocks and atom interferometers

2015 ◽  
Vol 95 ◽  
pp. 02002 ◽  
Author(s):  
Ruxandra Bondarescu ◽  
Andreas Schärer ◽  
Philippe Jetzer ◽  
Raymond Angélil ◽  
Prasenjit Saha ◽  
...  
Keyword(s):  
General Relativity ◽  
Alternative Theories Of Gravity ◽  
Atomic Clocks ◽  
Theories Of Gravity ◽  
Alternative Theories ◽  
Atom Interferometers

scholarly journals Testing the Vainshtein mechanism using stars and galaxies

2015 ◽  
Vol 24 (12) ◽  
pp. 1544021 ◽  
Author(s):  
Jeremy Sakstein ◽  
Kazuya Koyama
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Main Sequence ◽  
Alternative Theories Of Gravity ◽  
The Novel ◽  
Main Sequence Stars ◽  
Cosmic Expansion ◽  
Astrophysical Objects ◽  
Theories Of Gravity ◽  
Alternative Theories

The Vainshtein mechanism is of paramount importance in many alternative theories of gravity. It hides deviations from general relativity (GR) in the solar system while allowing them to drive the acceleration of the cosmic expansion. Recently, a class of theories have emerged where the mechanism is broken inside astrophysical objects. In this essay, we look for novel probes of these theories by deriving the modified properties of stars and galaxies. We show that main-sequence stars are colder, less luminous and more ephemeral than GR predicts. Furthermore, the circular velocities of objects orbiting inside galaxies are slower and the lensing of light is weaker. We discuss the prospects for testing these theories using the novel phenomena presented here in light of current astrophysical surveys.

scholarly journals ON GENERATING SOME KNOWN BLACK HOLE SOLUTIONS

2010 ◽  
Vol 25 (10) ◽  
pp. 835-842 ◽  
Author(s):  
F. RAHAMAN ◽  
MUBASHER JAMIL ◽  
A. GHOSH ◽  
K. CHAKRABORTY
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Alternative Theories Of Gravity ◽  
Dimensional Parameters ◽  
Theories Of Gravity ◽  
Alternative Theories ◽  
Black Hole Solutions

In this paper, we have presented an algorithm to generate various black hole solutions in general relativity and alternative theories of gravity. The algorithm involves few dimensional parameters that are assigned suitable values to specify the required black hole.

scholarly journals FOURTH-ORDER GRAVITY AND EXPERIMENTAL CONSTRAINTS ON EDDINGTON PARAMETERS

2006 ◽  
Vol 21 (30) ◽  
pp. 2291-2301 ◽  
Author(s):  
S. CAPOZZIELLO ◽  
A. STABILE ◽  
A. TROISI
Keyword(s):  
Experimental Data ◽  
General Relativity ◽  
Alternative Theories Of Gravity ◽  
Third Order ◽  
Definitive Answer ◽  
Order Polynomial ◽  
Theories Of Gravity ◽  
Definition Of ◽  
Ppn Parameters ◽  
Alternative Theories

PPN-limit of alternative theories of gravity represents a still controversial matter of debate and no definitive answer has been provided, up to now, about this issue. By using the definition of the PPN-parameters γ and β in terms of f(R) theories of gravity, we show that a family of third-order polynomial theories, in the Ricci scalar R, turns out to be compatible with the PPN-limit and the deviation from General Relativity, theoretically predicted, can agree with experimental data.

scholarly journals Renormalizability of Alternative Theories of Gravity: Differences between Power Counting and Entropy Argument

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 148
Author(s):  
Francesco Bajardi ◽  
Francesco Bascone ◽  
Salvatore Capozziello
Keyword(s):  
General Relativity ◽  
Teleparallel Gravity ◽  
Power Counting ◽  
Alternative Theories Of Gravity ◽  
Spherically Symmetric ◽  
Asymptotic Safety ◽  
Renormalizable Theory ◽  
Theories Of Gravity ◽  
Working Out ◽  
Alternative Theories

It is well known that General Relativity cannot be considered under the standard of a perturbatively renormalizable quantum field theory, but asymptotic safety is taken into account as a possibility for the formulation of gravity as a non-perturbative renormalizable theory. Recently, the entropy argument has however stepped into the discussion claiming for a “no-go” to the asymptotic safety argument. In this paper, we present simple counter-examples, considering alternative theories of gravity, to the entropy argument as further indications, among others, on the possible flows in the assumptions on which the latter is based. We considered different theories, namely curvature-based extensions of General Relativity as f(R), f(G), extensions of teleparallel gravity as f(T), and Horava–Lifshitz gravity, working out the explicit spherically symmetric solutions in order to make a comparison between power counting and the entropy argument. Even in these cases, inconsistencies were found.

scholarly journals Scalarized black holes

2021 ◽  
Author(s):  
Jose Luis Blázquez-Salcedo ◽  
Burkhard Kleihaus ◽  
Jutta Kunz
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Scalar Field ◽  
Alternative Theories Of Gravity ◽  
Gravitational Action ◽  
Theories Of Gravity ◽  
Bonnet Term ◽  
Alternative Theories ◽  
Black Hole Solutions

AbstractBlack holes represent outstanding astrophysical laboratories to test the strong gravity regime, since alternative theories of gravity may predict black hole solutions whose properties may differ distinctly from those of general relativity. When higher curvature terms are included in the gravitational action as, for instance, in the form of the Gauss–Bonnet term coupled to a scalar field, scalarized black holes result. Here we discuss several types of scalarized black holes and some of their properties.

scholarly journals TESTS OF GENERAL RELATIVITY AND ALTERNATIVE THEORIES OF GRAVITY USING GRAVITATIONAL WAVE OBSERVATIONS

2013 ◽  
Vol 22 (01) ◽  
pp. 1341012 ◽  
Author(s):  
K. G. ARUN ◽  
ARCHANA PAI
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Strong Field ◽  
Information Matrix ◽  
Simons Theory ◽  
Alternative Theories Of Gravity ◽  
Newtonian Theory ◽  
Theories Of Gravity ◽  
Model Independent ◽  
Alternative Theories

Gravitational wave (GW) observations of coalescing compact binaries will be unique probes of strong-field, dynamical aspects of relativistic gravity. We present a short review of various schemes proposed in the literature to test general relativity (GR) and alternative theories of gravity using inspiral waveforms. Broadly these schemes may be classified into two types: model dependent and model independent. In the model dependent category, GW observations are compared against a specific waveform model representative of a particular theory or a class of theories such as scalar-tensor theories, dynamical Chern–Simons theory and massive graviton theories. Model independent tests are attempts to write down a parametrized gravitational waveform where the free parameters take different values for different theories and (at least some of) which can be constrained by GW observations. We revisit some of the proposed bounds in the case of downscaled LISA configuration (eLISA) and compare them with the original LISA configuration. We also compare the expected bounds on alternative theories of gravity from ground-based and space-based detectors and find that space-based GW detectors can test GR and other theories of gravity with unprecedented accuracies. We then focus on a recent proposal to use singular value decomposition of the Fisher information matrix to improve the accuracies with which post-Newtonian theory can be tested. We extend those results to the case of space-based detector eLISA and discuss its implications.

scholarly journals Radioscience simulations in general relativity and in alternative theories of gravity

2012 ◽  
Vol 29 (23) ◽  
pp. 235027 ◽  
Author(s):  
A Hees ◽  
B Lamine ◽  
S Reynaud ◽  
M-T Jaekel ◽  
C Le Poncin-Lafitte ◽  
...  
Keyword(s):  
General Relativity ◽  
Alternative Theories Of Gravity ◽  
Theories Of Gravity ◽  
Alternative Theories

GENERAL RELATIVITY (PLUS DARK MATTER AND DARK ENERGY) OR ALTERNATIVE THEORIES OF GRAVITY

2008 ◽  
Author(s):  
A. F. ZAKHAROV ◽  
V. N. PERVUSHIN ◽  
F. DE PAOLIS ◽  
G. INGROSSO ◽  
A. A. NUCITA
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Alternative Theories Of Gravity ◽  
Theories Of Gravity ◽  
Alternative Theories

scholarly journals The Polarizations of Gravitational Waves

Universe ◽  
2018 ◽  
Vol 4 (8) ◽  
pp. 85 ◽  
Author(s):  
Yungui Gong ◽  
Shaoqi Hou
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
High Speed ◽  
Strong Field ◽  
Alternative Theories Of Gravity ◽  
Pulsar Timing ◽  
Theories Of Gravity ◽  
Alternative Theories

The gravitational wave provides a new method to examine General Relativity and its alternatives in the high speed, strong field regime. Alternative theories of gravity generally predict more polarizations than General Relativity, so it is important to study the polarization contents of theories of gravity to reveal the nature of gravity. In this talk, we analyze the polarization contents of Horndeski theory and f(R) gravity. We find out that in addition to the familiar plus and cross polarizations, a massless Horndeski theory predicts an extra transverse polarization, and there is a mix of pure longitudinal and transverse breathing polarizations in the massive Horndeski theory and f(R) gravity. It is possible to use pulsar timing arrays to detect the extra polarizations in these theories. We also point out that the classification of polarizations using Newman–Penrose variables cannot be applied to massive modes. It cannot be used to classify polarizations in Einstein-æther theory or generalized Tensor-Vector-Scalar (TeVeS) theory, either.

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