Modified Einstein versus Modified Euler for Dark Matter
| Autor: | Bonvin, Camille, Pogosian, Levon |
|---|---|
| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Nature Astronomy 7, 1127-1134 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1038/s41550-023-02003-y |
| Popis: | Modifications of General Relativity generically contain additional degrees of freedom that can mediate forces between matter particles. One of the common manifestations of a fifth force in alternative gravity theories is a difference between the gravitational potentials felt by relativistic and non-relativistic particles, also known as "the gravitational slip". In contrast, a fifth force between dark matter particles, due to dark sector interaction, does not cause a gravitational slip, making the latter a possible smoking gun of modified gravity. In this article, we point out that a force acting on dark matter particles, as in models of coupled quintessence, would also manifest itself as a measurement of an effective gravitational slip by cosmological surveys of large-scale structure. This is linked to the fact that redshift-space distortions due to peculiar motion of galaxies do not provide a measurement of the true gravitational potential if dark matter is affected by a fifth force. Hence, it is extremely challenging to distinguish a dark sector interaction from a modification of gravity with cosmological data alone. Future observations of gravitational redshift from galaxy surveys can help to break the degeneracy between these possibilities, by providing a direct measurement of the distortion of time. We discuss this and other possible ways to resolve this important question. Comment: 13 pages, 2 figures |
| Databáze: | arXiv |
| Externí odkaz: |
|