Determine the origin of the extended velocity structure and AGN contribution

Determine whether the rising velocity gradient in the extended nebula of AEON-z5 is produced by gravitationally supported or corotating gas, an AGN-driven outflow accelerating into a lower-density environment, recycled inflow, or a starburst-driven wind, and establish whether an active galactic nucleus is present in the central region.

Background

The F444W grism data show distinct kinematic behavior in the compact core and extended nebula: the core has a broad, multi-peaked emission-line profile, while the extended nebula exhibits a predominantly one-sided velocity gradient whose centroid shifts redward with projected radius. The paper discusses four possible interpretations: gravitationally supported or corotating outer gas, an accelerating AGN-driven outflow, recycled inflow in a galactic-fountain cycle, and an extreme starburst-driven wind.

The available imaging, slitless-grism spectroscopy, and SED modeling do not uniquely determine the gas geometry or excitation source. The authors identify spatially resolved integral-field spectroscopy, an independent systemic-redshift measurement from cold gas, and a direct continuum-size measurement as necessary to distinguish among these scenarios and clarify the role of an AGN.