HI-Optical Tidal Morphologies

The Neutral Hydrogen Distribution in Merging Galaxies:
Differences between Optical and Gaseous Tidal Morphologies

J. E. Hibbard, W. D. Vacca & M. S. Yun

The Astronomical Journal, 119, 1130 (2000) (pdf) (ADS)

As part of several HI synthesis mapping studies of merging galaxies, we have mapped the tidal gas in three disk-disk merger systems: Arp 157 (NGC 520), Arp 220, and Arp 299 (NGC 3690). These systems differ from the majority of the mergers mapped in HI, in that their optical and gaseous tidal morphologies are very different. In particular, they exhibit large optical tidal features with little if any accompanying neutral gas and large gas-rich tidal features with little if any accompanying starlight. On a smaller scale, there are striking anti-correlations where the gaseous and optical tidal features appear to cross. We explore several possible explanations for these differences, including dust obscuration, ram pressure stripping, and ionization effects. No single explanation can account for all of the observed differences. The fact that each of these systems shows evidence for a starburst driven superwind expanding in the direction of the most dramatic tidal displacements leads us to suggest that the wind plays a role in shaping the morphology of the tidal gas.

Index: Bonus Figures:
Maintained by jhibbard @ nrao.edu

Last modified: Tue Apr 30 16:00:06 EDT 2002