What controls the ionized gas turbulent motions in dwarf galaxies?

TL;DR

This study investigates the factors influencing ionized gas turbulence in dwarf galaxies, revealing a strong correlation between star formation rate and gas velocity dispersion, primarily driven by star formation energy rather than gravitational virial motions.

Contribution

It establishes a global SFR-sigma relation across diverse galaxy types, highlighting star formation as the main driver of gas turbulence in dwarf galaxies.

Findings

SFR-sigma relation fitted as sigma~ SFR^(5.3)

Velocity dispersion mainly driven by star formation energy

Relation holds across various galaxy luminosities and types

Abstract

Using 3D spectroscopy with a scanning Fabry-Perot interferometer, we study the ionized gas kinematics in 59 nearby dwarf galaxies. Combining our results with data from literature, we provide a global relation between the gas velocity dispersion (sigma) and the star formation rate (SFR) and H\alpha luminosity for galaxies in a very broad range of star formation rates SFR=0.001-300 Msun/yr. We find that the SFR-sigma relation for the combined sample of dwarf galaxies, star forming, local luminous, and ultra-luminous infrared galaxies can be fitted as sigma~ SFR^(5.3+-0.2). This implies that the slope of the L-sigma relation inferred from the sample of rotation supported disc galaxies (including mergers) is similar to the L-sigma relation of individual giant HII regions. We present arguments that the velocity dispersion of the ionized gas does not reflect the virial motions in the gravitational potential of dwarf galaxies, and instead is mainly determined by the energy injected into the interstellar medium by the ongoing star formation.