Flat spiral galaxy rotation curves naturally follow from dark matter filaments

In this theory poster contribution I discuss how the known flattening of spiral-galaxy rotation curves is natural if, outside the galaxy's center, the gravitational potential corresponds to that of a filament, string or otherwise cylindrical structure perpendicular to the galactic plane. While observational evidence and simulations for filamentary structure at larger scales seem solid, it is less clear at scales commensurable with galactic sizes. If nevertheless the hypothesis of an at least partially filamentary source of gravity is temptatively adopted for spiral galaxies, the exponent of the baryonic Tully-Fisher relation due to accretion of visible matter by the filament comes out to reasonably be 4. At a minimum, given this exact analytic limit linking cylindrical sources to constant rotation speed, the relation between galactic haloes and rotation curves should become more natural in simulations if instead of spherical, the dark haloes are allowed to be very prolate