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MOND and the presence of the external field effect in galaxies
April 23 @ 2:30 pm - 3:30 pm
Abstract: Modified Newtonian Dynamics (MOND) is an alternate theory of gravity first proposed in 1983 to contend with the hidden mass hypothesis to explain the motion of mass within galaxies. The MOND theory relies on an acceleration constant, a_0, such that systems where the acceleration is large (a≫ a_0), the usual Newtonian dynamics holds but systems with a small acceleration (a≪ a_0), are governed by this modified form of Newtonian dynamics. An important result of MOND is that the internal dynamics of a system in an external gravitational field is expected to depend on that external field; the strong equivalence principle of general relativity requires that this external field effect (EFE) is not present. A recent study of galaxies from the Spitzer Photometry and Accurate Rotation Curves (SPARC) sample has produced a detection of the EFE in galaxies under an external field from neighbouring galaxies, suggesting that alternate theories of gravity, like MOND, are needed to fully explain the dynamics within galaxies.
If you would like to participate in this seminar please contact Nancy Robichaud at firstname.lastname@example.org to obtain the zoom link BEFORE Thursday, April 22.