scholarly journals SOLAR SYSTEM TESTS OF f(R) GRAVITY

2014 ◽  
Vol 23 (04) ◽  
pp. 1450036 ◽  
Author(s):  
JUN-QI GUO
Keyword(s):  
Solar System ◽  
Functional Form ◽  
Equations Of Motion ◽  
Jordan Frame ◽  
The Sun ◽  
False Vacuum ◽  
Vacuum Decay ◽  
Effective Potentials ◽  
Chameleon Mechanism ◽  
Numerical Approaches

In this paper, we revisit the solar system tests of f(R) gravity. When the sun sits in a vacuum, the field f′ is light, which leads to a metric different from the observations. We reobtain this result in a simpler way by directly focusing on the equations of motion for f(R) gravity in the Jordan frame (JF). The discrepancy between the metric in the f(R) gravity and the observations can be alleviated by the chameleon mechanism. The implications from the chameleon mechanism on the functional form f(R) are discussed. Considering the analogy of the solar system tests to the false vacuum decay problem, the effective potentials in different cases are also explored. The combination of analytic and numerical approaches enables us to ascertain whether an f(R) model can pass the solar system tests or not.

scholarly journals Fab Four: When John and George Play Gravitation and Cosmology

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
J.-P. Bruneton ◽  
M. Rinaldi ◽  
A. Kanfon ◽  
A. Hees ◽  
S. Schlögel ◽  
...  
Keyword(s):  
Scalar Field ◽  
Solar System ◽  
Parameter Space ◽  
Ad Hoc ◽  
Initial Conditions ◽  
Equations Of Motion ◽  
Inflationary Model ◽  
Einstein Tensor ◽  
Chameleon Mechanism ◽  
Derivatives Of

Scalar-tensor theories of gravitation attract again a great interest since the discovery of the Chameleon mechanism and of the Galileon models. The former allows reconciling the presence of a scalar field with the constraints from Solar System experiments. The latter leads to inflationary models that do not need ad hoc potentials. Further generalizations lead to a tensor-scalar theory, dubbed the “Fab Four,” with only first and second order derivatives of the fields in the equations of motion that self-tune to a vanishing cosmological constant. This model needs to be confronted with experimental data in order to constrain its large parameter space. We present some results regarding a subset of this theory named “John,” which corresponds to a nonminimal derivative coupling between the scalar field and the Einstein tensor in the action. We show that this coupling gives rise to an inflationary model with very unnatural initial conditions. Thus, we include the term named “George,” namely, a nonminimal, but nonderivative, coupling between the scalar field and Ricci scalar. We find a more natural inflationary model, and, by performing a post-Newtonian analysis, we derive the set of equations that constrain the parameter space with data from experiments in the Solar System.

scholarly journals New Approach to the Planetary Theory

1979 ◽  
Vol 81 ◽  
pp. 69-72 ◽  
Author(s):  
Manabu Yuasa ◽  
Gen'ichiro Hori
Keyword(s):  
Perturbation Method ◽  
Canonical Form ◽  
Equations Of Motion ◽  
Disturbing Function ◽  
Averaging Principle ◽  
The Sun ◽  
Planetary Theory ◽  
New Approach ◽  
Canonical Perturbation ◽  
Relative Coordinates

A new approach to the planetary theory is examined under the following procedure: 1) we use a canonical perturbation method based on the averaging principle; 2) we adopt Charlier's canonical relative coordinates fixed to the Sun, and the equations of motion of planets can be written in the canonical form; 3) we adopt some devices concerning the development of the disturbing function. Our development can be applied formally in the case of nearly intersecting orbits as the Neptune-Pluto system. Procedure 1) has been adopted by Message (1976).

O(3)-invariant tunnelling at false vacuum decay in general relativity

1991 ◽  
Vol T36 ◽  
pp. 269-275 ◽  
Author(s):  
V A Berezin ◽  
V A Kuzmin ◽  
I I Tkachev
Keyword(s):  
General Relativity ◽  
False Vacuum ◽  
Vacuum Decay

scholarly journals The Principle of Least Interaction Action

1974 ◽  
Vol 3 ◽  
pp. 489-489
Author(s):  
M. W. Ovenden
Keyword(s):  
Solar System ◽  
Planetary System ◽  
Satellite System ◽  
Asteroid Belt ◽  
Correct Prediction ◽  
The Sun ◽  
Approximate Methods ◽  
Satellites Of Jupiter ◽  
History Of ◽  
Minimum Interaction

AbstractThe intuitive notion that a satellite system will change its configuration rapidly when the satellites come close together, and slowly when they are far apart, is generalized to ‘The Principle of Least Interaction Action’, viz. that such a system will most often be found in a configuration for which the time-mean of the action associated with the mutual interaction of the satellites is a minimum. The principle has been confirmed by numerical integration of simulated systems with large relative masses. The principle lead to the correct prediction of the preference, in the solar system, for nearly-commensurable periods. Approximate methods for calculating the evolution of an actual satellite system over periods ˜ 109 yr show that the satellite system of Uranus, the five major satellites of Jupiter, and the five planets of Barnard’s star recently discovered, are all found very close to their respective minimum interaction distributions. Applied to the planetary system of the Sun, the principle requires that there was once a planet of mass ˜ 90 Mθ in the asteroid belt, which ‘disappeared’ relatively recently in the history of the solar system.

scholarly journals The frequency of stellar X-ray flares from a large-scale XMM-Newton sample

2015 ◽  
Vol 11 (S320) ◽  
pp. 134-137
Author(s):  
John P. Pye ◽  
Simon R. Rosen
Keyword(s):  
Solar System ◽  
Solar Flare ◽  
Space Weather ◽  
White Light ◽  
Large Scale ◽  
The Sun ◽  
X Ray ◽  
Cool Star ◽  
Exoplanetary Systems ◽  
Solar Type

AbstractWe present estimates of cool-star X-ray flare rates determined from the XMM-Tycho survey (Pyeet al. 2015, A&A, 581, A28), and compare them with previously published values for the Sun and for other stellar EUV and white-light samples. We demonstrate the importance of applying appropriate corrections, especially in regard to the total, effective size of the stellar sample. Our results are broadly consistent with rates reported in the literature for Kepler white-light flares from solar-type stars, and with extrapolations of solar flare rates, indicating the potential of stellar X-ray flare observations to address issues such as ‘space weather’ in exoplanetary systems and our own solar system.

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