Small scale turbulence alongside with large scale turbulence in a z~sim 2 star Forming Galaxy with outflowing wind, revealed by Multi-point structure functions

TL;DR

This study investigates the coexistence of small and large scale turbulence in a z~2 star-forming galaxy with outflows, revealing that stellar clusters may drive small scale turbulence alongside large scale mechanisms.

Contribution

It provides evidence for small scale turbulence in a high-redshift galaxy and links it to stellar subclumps and giant star clusters as potential drivers.

Findings

Detected small scale turbulence at ~240-290 pc scales.

Large scale turbulence driven by mechanisms lasting ~500 Myr.

Star clusters likely responsible for small scale turbulence and outflows.

Abstract

Recently, Goldman (2024) obtained evidence for a large scale compressible, Burgers turbulence in the ism of a gravitationally lensed, star-forming galaxy at $z = 1.87$, with an outflowing wind. The turbulent timescale on the largest spatial scale has been found to be ~500 Myr . This together with the large spatial scale of~ 6.4 kpc suggest a large scale generating mechanism (such as tidal interaction or merger) that lasted for ~500 Myr. On the other hand, the outflowing wind is much younger and is probably the result of the intense star formation. Therefore, could it be that the star formation drives also turbulence on small scales? In the present work we utilize multi-point second order structure functions to find whether there exists also a small scale turbulence in this galaxy, and if so, try to identify its drivers. We obtained evidence for small scale turbulence whose largest spatial scale ~240 pc for the nebular gas velocity field and ~ 290 pc$ for the outflowing wind velocity field. These values suggest that stellar sub clumps or giant star clusters with an high concentration of young massive stars could be responsible for both the outflow and for the small scale turbulence.