Dark-Matter Content of Early-Type Galaxies with Planetary Nebulae

N.R. Napolitano, A.J. Romanowsky, L Coccato, M. Capaccioli, N.G. Douglas, E. Noordermeer, M.R. Merrifield, K. Kuijken, M. Arnaboldi, O. Gerhard, K.C. Freeman, F. De Lorenzi, P. Das

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Abstract. We examine the dark matter properties of nearby early-type galaxies using plane- tary nebulae (PNe) as mass probes. We have designed a specialised instrument, the Planetary Nebula Spectrograph (PN.S) operating at the William Herschel telescope, with the purpose of measuring PN velocities with best efficiency. The primary scientific objective of this custom- built instrument is the study of the PN kinematics in 12 ordinary round galaxies. Preliminary results showing a dearth of dark matter in ordinary galaxies (Romanowsky et al. 2003) are now confirmed by the first complete PN.S datasets. On the other hand early-type galaxies with a “regular” dark matter content are starting to be observed among the brighter PN.S target sample, thus confirming a correlation between the global dark-to-luminous mass virial ratio (fDM = MDM/M⋆) and the galaxy luminosity and mass.
Original languageEnglish
Number of pages5
JournalProceedings of the International Astronomical Union
Publication statusPublished - 2007


  • dark matter
  • kinematics and dynamics
  • evolution
  • haloes
  • galaxies

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