## Abstract

It is a well-known fact that the Newtonian description of dynamics within Galaxies for its known matter content is in disagreement with the observations as the acceleration approaches a_{0} ≈ 1.2 × 10^{−10} m/s^{2} (slighter larger for clusters). Both the Dark Matter scenario and Modified Gravity Theories (MGT) fail to explain the existence of such an acceleration scale. Motivated by the closeness of the acceleration scale and the Hubble constant cH_{0} ≈ 10^{−9} h m/s^{2}, we are led to analyze whether this coincidence might have a Cosmological origin for scalar-tensor and spinor-tensor theories by performing detailed calculations for perturbations that represent the local matter distribution on the top of the cosmological background. Then, we solve the field equations for these perturbations in a power series in the present value of the Hubble constant. As we shall see, for both theories, the power expansion contains only even powers in the Hubble constant, a fact that renders the cosmological expansion irrelevant for the local dynamics.

Original language | English |
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Article number | 1417 |

Journal | Symmetry |

Volume | 13 |

Issue number | 8 |

DOIs | |

State | Published - Aug 2021 |

Externally published | Yes |

### Bibliographical note

Publisher Copyright:© 2021 by the author. Licensee MDPI, Basel, Switzerland.

## Keywords

- Alternatives to dark matter
- Cosmological expansion
- Galactic dynamics