Velocity dispersion measurements of dwarf galaxies in the Coma cluster – implications for the structure of the fundamental plane |
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| Authors: | A M Cody D Carter T J Bridges B Mobasher † B M Poggianti |
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| Institution: | Anglo-Australian Observatory, PO Box 296, Epping, NSW 1710, Australia;Astronomy Department, Caltech, MC 105-24, 1201 East California Blvd, Pasadena, CA 91125, USA;Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD;Engineering Physics and Astronomy, Department of Physics, Queen's University, Kingston, Ontario, K7L 3N6, Canada;University of California, Riverside, 900 University Ave., Riverside, CA 92521, USA;Osservatorio Astronomico di INAF, Universitàdi Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy |
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| Abstract: | We present intermediate-resolution spectroscopic data for a set of dwarf and giant galaxies in the Coma cluster, with ?20.6 < MR < ?15.7. The photometric and kinematic properties of the brighter galaxies can be cast in terms of parameters which present little scatter with respect to a set of scaling relations known as the fundamental plane. To determine the form of these fundamental scaling relations at lower luminosities, we have measured velocity dispersions for a sample comprising 69 galaxies on the border of the dwarf and giant regime. Combining these data with our photometric survey, we find a tight correlation of luminosity and velocity dispersion, L ∝σ2.0 , substantially flatter than the Faber–Jackson relation characterizing giant elliptical galaxies. In addition, the variation of mass-to-light ( M / L ) ratio with velocity dispersion is quite weak in our dwarf sample: M / L ∝σ0.2. Our overall results are consistent with theoretical models invoking large-scale mass removal and subsequent structural readjustment, e.g. as a result of galactic winds. |
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| Keywords: | galaxies: clusters: individual: Coma galaxies: dwarf galaxies: elliptical and lenticular cD galaxies: evolution galaxies: fundamental parameters galaxies: kinematics and dynamics |
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