The high‐mass end of the Tully–Fisher relation

We study the location of massive disc galaxies on the Tully–Fisher (TF) relation. Using a combination of K‐band photometry and high‐quality rotation curves, we show that in traditional formulations of the TF relation (using the width of the global H i profile or the maximum rotation velocity), galaxies with rotation velocities larger than 200 km s−1 lie systematically to the right of the relation defined by less massive systems, causing a characteristic ‘kink’ in the relations. Massive, early‐type disc galaxies in particular have a large offset, up to 1.5 mag, from the main relation defined by less massive and later‐type spirals. The presence of a change in slope at the high‐mass end of the TF relation has important consequences for the use of the TF relation as a tool for estimating distances to galaxies or for probing galaxy evolution. In particular, the luminosity evolution of massive galaxies since z≈ 1 may have been significantly larger than estimated in several recent studies. We also show that many of the galaxies with the largest offsets have declining rotation curves and that the change in slope largely disappears when we use the asymptotic rotation velocity as kinematic parameter. The remaining deviations from linearity can be removed when we simultaneously use the total baryonic mass (stars + gas) instead of the optical or near‐infrared luminosity. Our results strengthen the view that the TF relation fundamentally links the mass of dark matter haloes with the total baryonic mass embedded in them.