title: The Baryonic Tully-Fisher Relation.
abstract: We explore the Tully-Fisher relation over five decades in stellar mass in galaxies with circular velocities ranging over 30 less, similarVc less, similar300 km s-1. We find a clear break in the optical Tully-Fisher relation: field galaxies with Vc less, similar90 km s-1 fall below the relation defined by brighter galaxies. These faint galaxies, however, are very rich in gas; adding in the gas mass and plotting the baryonic disk mass Md=M*+Mgas in place of luminosity restores the single linear relation. The Tully-Fisher relation thus appears fundamentally to be a relation between rotation velocity and total baryonic mass of the form Md~V4c.
authors.initials: SS
authors.lastname: McGaugh
authors.initials: JM
authors.lastname: Schombert
authors.initials: GD
authors.lastname: Bothun
authors.lastname: de Blok WJ