Ionized Gas with Broad Emission Lines in the Nuclei of Ellipticals
Abstract
Ionized gas disks in the central regions of elliptical galaxies have proven to be a powerful tool for the determination of the true spatial shape and the central mass- to-light ratio of their host galaxies. We have obtained ground-based spectroscopic data which show that some of these ellipticals with ionized gas exhibit broad forbidden emission lines in their central regions. These might hint for the presence of either highly turbulent gas motions or a central dark mass. However, we are currently unable to distinguish between these two possibilities since we do not know the central distribution of the gas. We therefore propose to use WFPC2 to obtain V and I broad band images as well as narrow band images centered on the H-alpha+[N II] emission lines for 3 ellipticals in our sample: NGC 2325, NGC 2974, and NGC 3136. These galaxies are low radio emitters and show broad [N II] and [S II] emission lines. Detailed {photometric and dynamical} models will be constructed in an attempt to reproduce the observed surface brightness, flux distribution of the gas, and optical depth of the dust. Subsequently, we will derive theoretical line profiles of the ionized gas. These will be compared with our ground-based spectroscopy in order to constrain the mass of a possible central dark mass, and the amount of turbulence.
- Publication:
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HST Proposal
- Pub Date:
- July 1996
- Bibcode:
- 1996hst..prop.6822G