Testing modified gravity theories with numerical solutions of the external field effect in rotationally supported galaxies

Kyu Hyun Chae, Federico Lelli, Harry Desmond, Stacy S. McGaugh, James M. Schombert

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The strong equivalence principle is violated by gravity theories of Milgromian dynamics [modified Newtonian dynamics (MOND)] through the action of the external field effect. We test two different Lagrangian theories Aquadratic-Lagrangian (AQUAL) and quasilinear MOND (QUMOND) based on their numerical solutions of the external field effect, by comparing two independent estimates of the mean external field strength of the nearby universe: a theory-deduced value from fitting the outer rotation curves of 114 galaxies and an empirical value from the large-scale distribution of cosmic baryons. The AQUAL-deduced external field strength from rotation curves agrees with that from the large-scale cosmic environment, while QUMOND-deduced value is somewhat higher. This suggests that AQUAL is likely to be preferred over QUMOND as an effective nonrelativistic limit of a potential relativistic modified gravity theory.

Original languageEnglish
Article number103025
Number of pages7
JournalPhysical Review D
Issue number10
Early online date15 Nov 2022
Publication statusPublished - 21 Nov 2022

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