The baryonic Tully-Fisher relation and its implication for dark matter halos

TL;DR

This study investigates whether low-mass dwarf galaxies follow the same baryonic Tully-Fisher relation as high-mass galaxies, and uses this to constrain dark matter halo shapes, finding the relation is fundamental across galaxy types.

Contribution

It demonstrates that dwarf galaxies adhere to the BTF relation and constrains dark matter halo ellipticities, extending the relation's applicability to low-mass galaxies.

Findings

Dwarf galaxies follow the same BTF relation as high-mass galaxies.

The scatter in the BTF constrains dark matter halo ellipticities to 0-0.06.

The BTF relation appears to be fundamental for rotationally dominated galaxies.

Abstract

The baryonic Tully-Fisher relation (BTF) is a fundamental relation between baryonic mass and maximum rotation velocity. It can be used to estimate distances, as well as to constrain the properties of dark matter and its relation with the visible matter. In this paper, we explore if extremely low-mass dwarf galaxies follow the same BTF relation as high-mass galaxies. We quantify the scatter in the BTF relation and use this to constrain the allowed elongations of dark matter halo potentials. We obtained HI synthesis data of 11 dwarf galaxies and derive several independent estimates for the maximum rotation velocity. Constructing a BTF relation using data from the literature for the high-mass end, and galaxies with detected rotation from our sample for the low-mass end results in a BTF with a scatter of 0.33 mag. This scatter constrains the ellipticities of the potentials in the plane of the disks of the galaxies to an upper limit of 0-0.06 indicating that dwarf galaxies are at most only mildly tri-axial. Our results indicate that the BTF relation is a fundamental relation which all rotationally dominated galaxies seem to follow.