Kinematics, abundances and origin of brightest cluster galaxies |
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| Authors: | D Carter T J Bridges G K T Hau |
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| Institution: | Liverpool John Moores University, Astrophysics Research Institute, Twelve Quays House, Egerton Wharf, Birkenhead, Wirral L41 1LD; Royal Greenwich Observatory;, Madingley Road, Cambridge CB3 0EZ Institute of Astronomy, Madingley Road, Cambridge CB3 0HA; Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 104, Santiago 22, Chile |
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| Abstract: | We present kinematic parameters and absorption line strengths for three brightest cluster galaxies, NGC 6166, 6173 and 6086. We find that NGC 6166 has a velocity dispersion profile which rises beyond 20 arcsec from the nucleus, with a halo velocity dispersion in excess of 400 km s?1. All three galaxies show a positive and constant h 4 Hermite moment. The rising velocity dispersion profile in NGC 6166 thus indicates an increasing mass-to-light ratio. Rotation is low in all three galaxies, and NGC 6173 and 6086 show possible kinematically decoupled cores. All three galaxies have Mg2 gradients similar to those found in normal bright ellipticals, which are not steep enough to support simple dissipative collapse models, but these could be accompanied by dissipationless mergers which would tend to dilute the abundance gradients. The Mg/Fe] ratios in NGC 6166 and 6086 are higher than that found in NGC 6173, and if NGC 6173 is typical of normal bright ellipticals, this suggests that cDs cannot form from late mergers of normal galaxies. |
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| Keywords: | galaxies: abundancies galaxies: elliptical and lenticular cD galaxies: general galaxies: kinematics and dynamics |
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