The morphological dependent Tully-Fisher relation of spiral galaxies

TL;DR

This paper investigates how the Tully-Fisher relation varies with galaxy morphology, revealing that stellar population differences, rather than rotation velocity, primarily drive the observed luminosity variations across types.

Contribution

It demonstrates that the morphological dependence of the Tully-Fisher relation is mainly due to stellar population differences, not changes in maximum rotation velocity.

Findings

Earlier type spirals are less luminous at fixed Vmax.

Luminosity differences are more pronounced in shorter wavelengths.

Stellar population effects explain the morphological dependence.

Abstract

The Tully-Fisher relation of spiral galaxies shows notable dependence on morphological types, with earlier type spirals having systematically lower luminosity at fixed maximum rotation velocity $V_{max}$. This decrement of luminosity is more significant in shorter wavelengths. By modeling the rotation curve and stellar population of different morphological type spiral galaxies in combination, we find the $V_{max}$ of spiral galaxies is weakly dependent on the morphological type, whereas the difference of the stellar population originating from the bulge disk composition effect mainly account for the morphological type dependence of the Tully-Fisher relation.