Physical origin of non-circular motions in REBELS-25

Determine whether the non-circular motions observed in the [C ii] and [O iii]88 μm emission of REBELS-25 are driven by outflows, inflows, minor mergers, other interactions, or observational noise.

Background

The [C ii] and [O iii]88 μm velocity fields are broadly consistent with a common rotating disc, but residuals in the fitted velocity and dispersion maps, warped isovelocity contours, and possible additional spectral components indicate departures from a simple circular-disc model.

The available data have limited signal-to-noise and spatial resolution, so the authors cannot distinguish among several possible physical explanations for these departures. Resolving this issue is important for determining whether REBELS-25 is undergoing assembly through accretion, feedback, or interactions while retaining ordered rotation.