Neutral Hydrogen Tully Fisher Relation : The case for Newtonian Gravity

Abstract

Intrinsic luminosities are related to rotation velocities of disk galaxies by Tully Fisher (TF) relations. The Baryonic TF (BTF) relation has recently been explained with Dark Matter and Newtonian Gravity as well as Modified Newtonian Dynamics (MOND). However, recent work has pointed out that the currently used BTF relation ignores the contribution from hot gas and oversimplifies complex galaxy-scale physics. In this Letter, we advocate the use of the Neutral Hydrogen TF (HITF) relationship, which is free from dust obscuration and stellar evolution effects, as a clean probe of gravity and dynamics in the weak field regime. We incorporate the physics of hot gas from supernova feedback which drives the porosity of the Interstellar Medium (ISM). A simple model that includes supernovae feedback, is generalized to include a parametrized effective gravitational force law. We test our model against a catalogue of galaxies, spanning the full range of disks from dwarf galaxies to giant spirals, to demonstrate that a Kennicutt-Schmidt (KS) law for star formation and simple Newtonian gravity is adequate for explaining the observed HI scaling relations. The data rules out MOND-like theories, within the scope of this model.