Author ORCID Identifier
Document Type
Article
Publication Date
12-17-2014
Abstract
I review the connection between dynamics and the baryonic mass distribution in rotationally-supported galaxies. The enclosed dynamical mass-to-light ratio increases with decreasing galaxy luminosity and surface brightness. The correlation with surface brightness appears to be the more fundamental, with the dependence on luminosity following simply from the weaker correlation between luminosity and surface brightness. In addition to this global relation, there is also a local relation between the amplitude of the mass discrepancy and the acceleration predicted by the observed distribution of baryons. I provide an empirical calibration of this mass discrepancy-acceleration relation. The data are consistent with the operation of a singe effective force law in disk galaxies, making this relation tantamount to a natural law. I further provide formulae by which the radial dark matter distribution can be estimated from surface photometry. The form of the dark matter halo depends uniquely on the distribution of baryons in each galaxy and, in general, is neither a cusp nor a core. It remains difficult to see how galaxy formation models can reproduce the observed behavior, which is uniquely predicted by MOND.
Keywords
dark matter, galaxies: formation, galaxies: kinematics and dynamics, galaxies: structure
Language
622
Publication Title
Galaxies
Grant
NNX13AH32G
Rights
© 2014 by the author. Licensee MDPI, Basel, Switzerland. This is an Open Access work distributed under the terms of the Creative Commons Attribution Licence (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
McGaugh, S. S. (2014). The Third Law of Galactic Rotation. Galaxies, 2(4), 601-622. https://doi.org/10.3390/galaxies2040601
Manuscript Version
Final Publisher Version