Corrugations in the Disk of the Edge-On Spiral Galaxy IC2233

TL;DR

This study investigates the vertical corrugation patterns in the HI disk of the edge-on galaxy IC2233 across multiple wavelengths, linking these patterns to star formation regulation and galactic gravitational instabilities.

Contribution

It provides multi-wavelength measurements of vertical structures in IC2233 and explores their origins, emphasizing the role of global gravitational instabilities over other mechanisms.

Findings

Corrugation amplitude ~250 pc observed in young stars and gas

Vertical displacements correlate with velocity undulations in HI rotation curve

Global gravitational instabilities likely cause the observed corrugations

Abstract

We recently reported the discovery of a regular corrugation pattern in the HI disk of the isolated, edge-on spiral galaxy IC2233. Here we present measurements of the vertical structure of this galaxy at several additional wavelengths, ranging from the far ultraviolet to the far infrared. We find that undular patterns with amplitude ~5''(~250 pc) are visible in a variety of Population I tracers in IC2233, including the young-to-intermediate age stars, the HII regions, and the dust. However, the vertical excursions become less pronounced in the older stellar populations traced by the mid-infrared light. This suggests that the process leading to the vertical displacements may be linked with the regulation of star formation in the galaxy. We have also identified a relationship between the locations of the density corrugations and small-amplitude (~5 km/s) velocity undulations in the HI rotation curve. We are able to exclude several possible mechanisms for the origin of the observed corrugations, including tidal interaction from a companion, Parker instabilities, or a galactic bore. Global gravitational instabilities appear to be the most likely explanation, although local perturbations may also be important.