Modified Newtonian Dynamics: where does it work, and where does it not? -- Benoit Famaey -- Université Libre de Bruxelles
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Europe/Paris
Description
I will review the evidence for a one-to-one analytic relation between the inferred gravity of
dark matter at any radius and the enclosed baryonic mass in galaxies, a relation summarized by
Milgrom's law of modified Newtonian dynamics (MOND). However, present-day covariant versions of
MOND usually require some additional fields contributing to the geometry, as well as an
additional hot dark matter component to explain cluster dynamics. I will notably show how the
gravitational lensing map of the bullet cluster constrains this hot dark matter component. I will
finally suggest that dark matter could at the same time exist and be the source of MOND-like
phenomenology in galaxies, by assuming a canonical action for dark matter, but also adding an
interaction term between baryonic matter, gravity, and dark matter, such that standard matter
effectively obeys the MOND field equation in galaxies.