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C. Mihos (CWRU)
Kiloparsec-scale offsets are sometimes observed between the gaseous and stellar components in tidal debris. These observations have led to models in which offsets are explained by hydrodynamic interactions between the tidal gas and a hot gas component, either an X-ray halo or outflowing starburst wind. In fact, these gas/star offsets can be simply explained by differences between the initial distribution of gas and stars in the progenitor disks, coupled with dissipation in the gasous component. Because HI disks are more extended than their stellar counterparts, they contain more angular momenta; once the tidal tails are launched, the high angular momenta gas tends to lead the low angular momenta stellar component. This kinematic evolution explains the observed gas/star offsets in interacting galaxies without invoking any additional (unseen) gaseous component.
This work has been sponsored through a National Science Foundation Early Career Award.