[31.04] Some Dynamical Constraints on the Halo of NGC 3379 from Wide-Field Spectroscopy of Its Globular Cluster System

AAS 205th Meeting, 9-13 January 2005
Session 31 Evolution of Ellipticals and Dark Matter Halos
Oral, Monday, January 10, 2005, 10:00-11:30am, California

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[31.04] Some Dynamical Constraints on the Halo of NGC 3379 from Wide-Field Spectroscopy of Its Globular Cluster System

S.E. Zepf, G. Bergond (Michigan State University), A.J. Romanowsky (University of Nottingham), K.L. Rhode (Wesleyan Univ./Yale Univ.), R.M. Sharples (University of Durham)

We present initial results from a study of the dynamics of the outer halo of the nearby elliptical galaxy NGC 3379 based on wide-field spectroscopy of its globular cluster system. Our study uses the FLAMES multi-object spectrograph at the VLT to determine the radial velocities of candidate gloublar clusters previously identified in CCD Mosaic images of nearby elliptical galaxies. Over the large radial range of 0.7 to 15 arcminutes (2 to 45 kpc) covered by our study, the velocity dispersion of the globular cluster system suggests the presence of a dark matter halo around NGC 3379, consistent with the observed rotation of an HI ring at larger distances. A less significant dark matter halo has been suggested by studies of the planetary nebulae, and we discuss possible reasons for this difference. SEZ and KLR acknowledge support from NSF grants AST-0406891 and AST-0302095 respectively.

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