scholarly journals Equivalence principle implications of modified gravity models

2009 ◽  
Vol 80 (10) ◽  
Author(s):  
Lam Hui ◽  
Alberto Nicolis ◽  
Christopher W. Stubbs
Keyword(s):  
Modified Gravity ◽  
Equivalence Principle ◽  
Gravity Models ◽  
Modified Gravity Models

scholarly journals Dwarf galaxies without dark matter: constraints on modified gravity

2020 ◽  
Vol 501 (1) ◽  
pp. 254-260
Author(s):  
Ali Rida Khalifeh ◽  
Raul Jimenez
Keyword(s):  
Dark Matter ◽  
Modified Gravity ◽  
Virial Theorem ◽  
Dwarf Galaxies ◽  
Strong Support ◽  
Gravity Models ◽  
Birkhoff Theorem ◽  
Astronomical Surveys ◽  
Stringent Test ◽  
Modified Gravity Models

ABSTRACT The discovery of 19 dwarf galaxies without dark matter (DM) provides, counterintuitively, strong support for the ΛCDM standard model of cosmology. Their presence is well accommodated in a scenario where the DM is in the form of cold dark particles. However, it is interesting to explore quantitatively what is needed from modified gravity models to accommodate the presence of these galaxies and what extra degree of freedom is needed in these models. To this end, we derive the dynamics at galaxy scales (Virial theorem) for a general class of modified gravity models. We distinguish between theories that satisfy the Jebsen–Birkhoff theorem, and those that do not. Our aim is to develop tests that can distinguish whether DM is part of the theory of gravity or a particle. The 19 dwarf galaxies discovered provide us with a stringent test for models of modified gravity. Our main finding is that there will always be an extra contribution to the Virial theorem coming from the modification of gravity, even if a certain galaxy shows very small, if not negligible, trace of DM, as has been reported recently. Thus, if these and more galaxies are confirmed as devoid (or negligible) of DM, while other similar galaxies have abundant DM, it seems interesting to find modifications of gravity to describe DM. Our result can be used by future astronomical surveys to put constraints on the parameters of modified gravity models at astrophysical scales where DM is described as such.

scholarly journals Modified Gravity Models Admitting Second Order Equations of Motion

Entropy ◽  
2015 ◽  
Vol 17 (12) ◽  
pp. 6643-6662 ◽  
Author(s):  
Aimeric Colléaux ◽  
Sergio Zerbini
Keyword(s):  
Modified Gravity ◽  
Equations Of Motion ◽  
Second Order ◽  
Gravity Models ◽  
Second Order Equations ◽  
Modified Gravity Models

scholarly journals Testing modified gravity models with recent cosmological observations

2012 ◽  
Vol 55 (12) ◽  
pp. 2244-2258 ◽  
Author(s):  
WenShuai Zhang ◽  
Cheng Cheng ◽  
QingGuo Huang ◽  
Miao Li ◽  
Song Li ◽  
...  
Keyword(s):  
Modified Gravity ◽  
Gravity Models ◽  
Cosmological Observations ◽  
Modified Gravity Models

scholarly journals Cosmology of generalized modified gravity models

2005 ◽  
Vol 71 (6) ◽  
Author(s):  
Sean M. Carroll ◽  
Antonio De Felice ◽  
Vikram Duvvuri ◽  
Damien A. Easson ◽  
Mark Trodden ◽  
...  
Keyword(s):  
Modified Gravity ◽  
Gravity Models ◽  
Modified Gravity Models

scholarly journals Exact Solutions in Modified Gravity Models

Entropy ◽  
2012 ◽  
Vol 14 (7) ◽  
pp. 1140-1153 ◽  
Author(s):  
Andrey N. Makarenko ◽  
Valery V. Obukhov
Keyword(s):  
Exact Solutions ◽  
Modified Gravity ◽  
Gravity Models ◽  
Modified Gravity Models
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