Creation and Destruction of Dwarf Galaxies in Interactions: Evaluating the Environmental Influences and the Global Importance

AST-0071223

Jane Charlton

The aim of this proposal is to conduct a detailed investigation of 838 dwarf galaxy candidates in 34 Hickson Compact groups. The plan is to obtain spectroscopy (to derive metalicities), multiband imaging (to investigate stellar populations and ages) and HI observations (to identify tidal tails). These observations will be used to try and distinguish between dwarf galaxies which have been formed in the debris left behind when larger galaxies were tidally disrupted and those which were formed primordially.

Tidal dwarf galaxies have long been recognized as occasional interlopers in the debris of galaxy interactions. The proposers have recently conducted a census of the dwarf galaxy population in Hickson compact groups, and the results strongly suggest that tidal dwarf galaxy formation is quite common. Depending on the survivability of the population, this process may be

quite significant, even as compared to primordial formation of dwarfs. The proposed project incorporates spectra obtained with the 8-m Hobby-Eberly Telescope, Hubble Space Telescope images, and Very Large array radio maps of the neutral Hydrogen from which the dwarfs form. With these data, we will compare properties of tidal dwarf galaxies to the galaxies at large in the groups, look for HI bridges connecting departing dwarfs to their parents, and assess the survivability of the dwarfs in the compact group environment. If the results of this study are extrapolated to consider other environments, it will be possible to evaluate if tidal dwarf formation is merely one of the occasional curiosities of the universe, or if it is important to our overall understanding of galaxy formation. Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC).

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