POWRE: The Evolution of Elliptical Galaxies: New Clues from Neutral Gas

New Mexico Institute Of Mining And Technology, Socorro NM

Investigators

Abstract

AST-007409 Young In recent years it has become clear that elliptical galaxies are not dead, gas-free galaxies as they were once thought to be. Many of them contain neutral gas, which raises the interesting possibility that they may be forming stars. A complete understanding of elliptical galaxy evolution depends on knowing the origin and the fate of this neutral gas and the star formation rate in elliptical galaxies. High resolution images made from observations of the carbon monoxide (CO) and hydrogen (HI) emission lines from nine elliptical galaxies will be made with the Berkeley, Illinois, and Maryland (BIMA) and Owens Valley Radio Observatory (OVRO) millimeter wavelength radio telescope interferometers and with the Very Large Array (VLA) radio telescope. The analysis of the data on the neutral gas distribution and kinematics will give vital clues to its origin and its fate. For example, the analysis of the data will show whether the gas was acquired in a violent merger, whether the gas is forming stars, is feeding an active galactic nucleus, or is being destroyed by some other process. The knowledge about the gas distribution and kinematics will also help explain the origin of the radio-FIR correlation in elliptical galaxies and will reveal the effects of a galaxy's environment on its neutral gas. The answers to these questions are not known because there are very few elliptical galaxies with good data on the distribution of their molecular and atomic gas. The results from this project will more than double the number of elliptical galaxies with good CO and HI emission line maps. The sample galaxies have a wide range of properties (including environment, morphology, luminosity. and strength of nuclear continuum source), that will help to disentangle the many processes affecting elliptical galaxies. The result from the project will be a unique synthesis of information that will help to give a better global picture of elliptical galaxies and their interstellar media. The project's results on the star formation rates in individual elliptical galaxies will be combined with the statistical work of Cotton & London (1998) to give the first quantitative picture of star formation in elliptical galaxies. The results of this project will also he used to refine the theoretical models of elliptical galaxy evolution. Finally, by showing how elliptical galaxies are evolving today, the project will help to draw the connections between high redshift and low redshift galaxies. This project is funded by the Division of Astronomical Sciences and the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate. ***