High star formation rates as the origin of turbulence in early and modern disk galaxies

TL;DR

This paper proposes that star formation activity, rather than cosmic accretion, is the primary driver of turbulence in galaxy disks across cosmic time, based on observations of nearby high-dispersion galaxies.

Contribution

It introduces a new sample of nearby high-dispersion galaxies showing star formation as the main turbulence driver, challenging previous accretion-based models.

Findings

Velocity dispersion correlates with star formation rates.

Cold accretion unlikely to explain high turbulence in nearby galaxies.

Star formation energizes galaxy disk turbulence across epochs.

Abstract

High spatial and spectral resolution observations of star formation and kinematics in early galaxies have shown that two-thirds are massive rotating disk galaxies with the remainder being less massive non-rotating objects. The line of sight averaged velocity dispersions are typically five times higher than in today's disk galaxies. This has suggested that gravitationally-unstable, gas-rich disks in the early Universe are fuelled by cold, dense accreting gas flowing along cosmic filaments and penetrating hot galactic gas halos. However these accreting flows have not been observed, and cosmic accretion cannot power the observed level of turbulence. Here we report on a new sample of rare high-velocity-dispersion disk galaxies we have discovered in the nearby Universe where cold accretion is unlikely to drive their high star-formation rates. We find that the velocity dispersion is most fundamentally correlated with their star-formation rates, and not their mass nor gas fraction, which leads to a new picture where star formation itself is the energetic driver of galaxy disk turbulence at all cosmic epochs.