http://arxiv.org/abs/1912.08592
We derive the dynamics at galaxy scales (Virial theorem) for modified gravity models in the general Hordensky class. Our aim is to develop tests that can distinguish whether dark matter is part of the theory of gravity or a particle. The recent discovery that a small number of dwarf galaxies lack any dark matter provides us with a stringent test for models of modified gravity. If there are only a few galaxies without dark matter, it is interesting to envision how to explain this if dark matter is a modification of gravity without adding epicycles to the model. We quantify this, and 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 dark matter, as has been reported recently [1-3]. Thus, if these and more galaxies are confirmed as devoid (or negligible) of dark matter, while other similar galaxies have abundant dark matter, it seems interesting to find modifications of gravity to describe dark matter. Our result can be used by future astronomical surveys to put constraints on the parameters of modified gravity models at astrophysical scales where dark matter is described as such.
A. Khalifeh and R. Jimenez
Fri, 20 Dec 19
47/63
Comments: N/A
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