A linear near-IR Tully-Fisher relation for giant and dwarf late-type galaxies

We present the near-IR (K′-band, i.e.: λ = 2.1 μm) Tully-Fisher (TF) relation for a sample of 50 giant and dwarf late-type galaxies, selected from the Virgo Cluster Catalogue. We find that L ∝ V 4 Max along a range of 8 K′-mag for galaxies with different Hubble types (from Sa to Im-BCD), phenomenologies, structures, star-formation histories, masses, dark-to-luminous mass ratios, metallicities and, perhaps, ages. The linearity of the near-IR TF relation is in contrast with recent determinations of the optical TF relations for samples of extreme late-type and dwarf galaxies. The near-IR TF law is in agreement both with the expectation from the Fundamental Plane for disk systems and with the scenario of self-regulating star-formation in disks. The previous results suggest that the TF relation reflects the connection between the structural/dynamical properties and the star-formation process of both giant and dwarf late-type galaxies, through a gas supply for star-formation regulated by the gravitational potential of the galaxy.