Professor James O’Brien Published in PRL

A recent work of Professor James O’Brien has been selected for publication in Physical Review Letters, the most prestigious of physics journals.


Impact of a Global Quadratic Potential on Galactic Rotation Curves

by Philip D. Mannheim and James G. O'Brien

 

Abstract: Dispensing with Dark Matter

We have made a fit to the rotation curves of a sample of 111 spiral galaxies, to find that we can account for them without the need for any galactic dark matter whatsoever. We solve a particular candidate alternative theory to standard gravity, namely conformal gravity, to find that the entire departure from the Newtonian gravity contribution produced by the luminous material in the galaxies can be described in a universal way. Unlike standard Newtonian gravity where one only needs to consider the local material within the galaxies themselves (to hence require galactic dark matter), in conformal gravity there is also a Machian-like contribution to local galactic motions provided by the rest of the material in the Universe. This global physics contribution is found to consist of two components, an effective linear potential due to the background cosmology and an effective quadratic potential due to the inhomogeneities in it.  Both contributions are universal and act on all galaxies in the same way. Despite the complete lack of free parameters, when taken in conjunction with the conformal gravity contribution of the luminous material within the galaxies, the two global contributions are found to provide for an accounting of the rotation curve data of the entire sample. Our work thus suggests that invoking galactic dark matter is nothing more than an attempt to describe global physics effects in purely local galactic terms.

                                                                                                                                                                                                                                                                                                                  PRL Information

Dr. James G. O'Brien
Assistant Professor of Physics
Department of Applied Math and Sciences
Wentworth Institute of Technology
617-989-4426
obrienj10@wit.edu

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