Testing Dark Matter and Modifications to Gravity using Local Milky Way Observables. (arXiv:1812.08169v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Lisanti_M/0/1/0/all/0/1">Mariangela Lisanti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moschella_M/0/1/0/all/0/1">Matthew Moschella</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Outmezguine_N/0/1/0/all/0/1">Nadav Joseph Outmezguine</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Slone_O/0/1/0/all/0/1">Oren Slone</a>
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.
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.
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