The multi-wavelength Tully-Fisher relation: hunting for the intrinsic scatter

The statistical properties of the Tully-Fisher relation provide important constraints for semi-analytical models and numerical simulations of galaxy formation and evolution. Over the past decades, the scatter in the Tully-Fisher relation has been decreased significantly by accurate photometric measures in the NIR bands. However, the small measurement errors on total luminosity can no longer explain the observed scatter. Therefore, we abandon the classical concept of the Tully-Fisher relation as a correlation using the width of global HI profile and consider instead the internal kinematics of gas in galaxies.As it is still not clear at which wavelengths the smallest scatter in the relation can be achieved, we assemble the Tully-Fisher relation for a calibrator sample of galaxies with measured TRGB/Cepheid distances over the broad wavelength range from FUV to 22 mm. We implement an improved kinematic measure by deriving high quality rotation curves, taking into account warps and streaming motions in the disk due to spiral arms or a bar.As a result, our studies show that besides the wavelength dependence, statistical properties of the Tully-Fisher relation are highly sensitive to the internal kinematics of gas