http://arxiv.org/abs/1812.08169
Galactic rotation curves are often considered the first robust evidence for the existence of dark matter. However, even in the presence of a dark matter halo, other galactic-scale observations, such as the Baryonic Tully-Fisher Relation and the Radial Acceleration Relation, remain challenging to explain. This has motivated long-distance, infrared (IR) modifications to gravity as an alternative to the dark matter hypothesis. We present a framework to test a general class of IR gravity modifications using local Milky Way observables, including the vertical acceleration field, the rotation curve, the baryonic surface density, and the stellar disk profile. We focus on models that predict scalar amplifications of gravity, i.e., models that increase the magnitude but do not change the direction of the gravitational acceleration. MOdified Newtonian Dynamics (MOND) is one such example. We find that an IR modification to gravity of this type is in tension with observations of the Milky Way scale radius and bulge mass and that dark matter provides a better fit to the data. We conclude that models like MOND struggle to simultaneously explain both the rotational velocity and vertical motion of nearby stars in the Milky Way.
M. Lisanti, M. Moschella, N. Outmezguine, et. al.
Fri, 21 Dec 18
40/72
Comments: 19 pages, 9 figures
You must be logged in to post a comment.