期刊
NEW ASTRONOMY
卷 9, 期 5, 页码 329-342出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.newast.2003.12.004
关键词
Galaxies: elliptical and lenticular; cD; Galaxies: halos; Dark matter
资金
- Packard and Sloan foundations
- NSF [CAREER-0132953, AST-0071091]
- Alfred P. Sloan Foundation
- Participating Institutions
- National Aeronautics and Space Administration
- National Science Foundation
- US Department of Energy
- Japanese Monbukagakusho
- Max Planck Society
We study the variation of the dark matter mass fraction of elliptical galaxies as a function of their luminosity, stellar mass, and size using a sample of 29,469 elliptical galaxies culled from the Sloan Digital Sky Survey. We model ellipticals as a stellar Hernquist profile embedded in an adiabatically compressed dark matter halo. This model allows us to estimate a dynamical mass (M-dynm) at the half-light radius from the velocity dispersion of the spectra, and to compare these to the stellar mass estimates (M-dynm) from Kauffmann et al. [MNRAS 341 (2003) 33]. We find that M-*/L is independent of luminosity, while M-dynm/L, increases with luminosity, implying that the dark matter fraction increases with luminosity. We also observe that at a fixed luminosity or stellar mass, the dark matter fraction increases with increasing galaxy size or, equivalently, increases with decreasing surface brightness: high surface brightness galaxies show almost no evidence for dark matter, while in low surface brightness galaxies, the dark matter exceeds the stellar mass at the half-light radius. We relate this to the fundamental plane of elliptical galaxies, suggesting that the tilt of this plane from simple virial predictions is due to the dark matter in galaxies. We find that a simple model where galaxies are embedded in dark matter halos and have a star formation efficiency independent of their surface brightness explains these trends. We estimate the virial mass of ellipticals as being approximately 7-30 times their stellar mass, with the lower limit suggesting almost all of the gas within the virial radius is converted into stars. (C) 2003 Elsevier B.V. All rights reserved.
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