http://arxiv.org/abs/1810.04445
Flat rotation curves in disk galaxies represent the main evidence for large amounts of surrounding “dark” matter. Despite of the difficulty in identifying the dark matter contribution to the total mass density in our Galaxy, stellar kinematics, as tracer of gravitational potential, is the most reliable observable for gauging different matter components. Very recently, the Gaia mission has provided such data with unprecedented accuracy and consistency over a range of 11 kpc in Galactocentric distances. By fitting both a “classical” (which includes a DM halo) and a relativistic (as derived form a specialized solution of Einstein’s field equation) rotational curves to the Gaia-derived circular velocities of a homogenous sample of disk stars (the largest sample ever), we put forth the Ansatz that a stationary and axisymmetric galaxy-scale metric could “fill the gap” in a baryons-only Milky Way, suggestive of dragged star orbits along the background geometry generated by a rotating inner bulge. Therefore, in the context of Local Cosmology, our findings point to a Galaxy phase-space as the exterior gravitational field of a Kerr-like source without the need of extra-matter.
M. Crosta, M. Giammaria, M. Lattanzi, et. al.
Thu, 11 Oct 18
56/72
Comments: 16 pages, 1 figure, submitted version