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7. LARGE-SCALE MASS DISTRIBUTION OF BULGES

There is little to say about the (very) large-scale mass distribution of bulges, i.e. their dark matter content, as little is known. When there is neutral hydrogen and/or ionized gas, the usual kinematic tracers in disk galaxies, it often has a complicated geometry or is disturbed. As shown by Capaccioli et al. (1993), it is extremely hard to push traditional long-slit spectroscopy with integrated light to significant radii (2Re). They report for NGC3115 an increase in M / L from 6 to more than 10 as r goes from 1 to 2Re. Contrary to elliptical galaxies (e.g. Hui et al. 1995 for Cen A), there has been little use of globular clusters (GCs) and planetary nebulae (PN) as (stellar) tracers in bulges. Using GCs in NGC3115, Kavelaars (1998) shows that M / L ≈ 19 at 5Re, suggesting the presence of dark matter in the halo. This is assumed to be generic but should be verified. The GC system also shows a red rapidly rotating metal rich thick disk system and a blue slowly rotating metal poor halo system, which is not unusual. Results from polar-rings and other objects probing the potential perpendicular to the equatorial plane are discussed in detail by Sparke (these proceedings).

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