Reconciling MOND and dark matter?

Observations of galaxies suggest a one-to-one analytic relation between the inferred gravity of dark matter at any radius and the enclosed baryonic mass, a relation summarized by Milgrom's law of modified Newtonian dynamics (MOND). However, present-day covariant versions of MOND usually require...

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Bibliographic Details
Published in:Journal of cosmology and astroparticle physics 2009-03, Vol.2009 (3), p.021-21
Main Authors: Bruneton, Jean-Philippe, Liberati, Stefano, Sindoni, Lorenzo, Famaey, Benoit
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
BARYONS
CLASSICAL MECHANICS
COSMOLOGY
DENSITY
FIELD EQUATIONS
GALAXIES
GRAVITATION
INTERACTIONS
NONLUMINOUS MATTER
ORDER PARAMETERS
SCALARS
TENSORS
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Summary:Observations of galaxies suggest a one-to-one analytic relation between the inferred gravity of dark matter at any radius and the enclosed baryonic mass, 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 and cosmology. Here, we envisage a slightly more mundane explanation, suggesting that dark matter does exist but is the source of MOND-like phenomenology in galaxies. We assume a canonical action for dark matter, but also add an interaction term between baryonic matter, gravity, and dark matter, such that standard matter effectively obeys the MOND field equation in galaxies. We show that even the simplest realization of the framework leads to a model which reproduces some phenomenological predictions of cold dark matter (CDM) and MOND at those scales where these are most successful. We also devise a more general form of the interaction term, introducing the medium density as a new order parameter. This allows for new physical effects which should be amenable to observational tests in the near future. Hence, this very general framework, which can be furthermore related to a generalized scalar-tensor theory, opens the way to a possible unification of the successes of CDM and MOND at different scales.
ISSN:1475-7516
1475-7516
DOI:10.1088/1475-7516/2009/03/021