On the radial acceleration relation of $\Lambda$CDM satellite galaxies

Abstract

The radial acceleration measured in bright galaxies tightly correlates with that generated by the observed distribution of baryons, a phenomenon known as the radial acceleration relation (RAR). Dwarf spheroidal satellite galaxies have been recently found to depart from the extrapolation of the RAR measured for more massive objects but with a substantially larger scatter. If confirmed by new data, this result provides a powerful test of the theory of gravity at low accelerations that requires robust theoretical predictions. By using high-resolution hydrodynamical simulations, we show that, within the standard model of cosmology ($\Lambda$CDM), satellite galaxies are expected to follow the same RAR as brighter systems but with a much larger scatter which does not correlate with the physical properties of the galaxies. In the simulations, the RAR evolves mildly with redshift. Moreover, the acceleration due to the gravitational field of the host has no effect on the RAR. This is in contrast with the External Field Effect in Modified Newtonian Dynamics (MOND) which causes galaxies in strong external fields to deviate from the RAR. This difference between $\Lambda$CDM and MOND offers a possible way to discriminate between them.

5 pages, 4 figures, accepted for publication in PRL

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• NIHAO XVIII: Origin of the MOND phenomenology of galactic rotation curves in a LCDM universe
• The radial acceleration relation in a $\Lambda$CDM universe
• Yet another test of Radial Acceleration Relation for galaxy clusters
• The Effect of Adiabatic Compression on Dark Matter Halos and the Radial Acceleration Relation
• The number of dwarf satellites of disk galaxies versus their bulge mass in the standard model of cosmology
• Time evolution of the local gravitational parameters and gravitational wave polarizations in a relativistic MOND theory
• Evidence for Modified Newtonian Dynamics from Cavendish-type gravitational constant experiments
• MIGHTEE-HI: The radial acceleration relation with resolved stellar mass measurements
• Testing the Collisionless Nature of Dark Matter with the Radial Acceleration Relation in Galaxy Clusters
• The radial acceleration relation at the EDGE of galaxy formation: testing its universality in low-mass dwarf galaxies
• MUSE-DARK III: The evolution of the radial acceleration relation at intermediate redshifts