The central kinematics of NGC 1399 measured with 14pc resolution

Abstract

We present near infra-red (NIR) adaptive optics assisted spectroscopic observations of the CO ($\hat{I}”\hat{I}¼=2$) absorption bands towards the centre of the giant elliptical galaxy NGC 1399. The observations were made with NAOS-CONICA (ESO VLT) and have a FWHM resolution of 0\farcs15 (14pc). Kinematic analysis of the observations reveals a decoupled core and strongly non-Gaussian line-of-sight velocity profiles (VPs) in the central 0.2 arcsec (19pc). NIR imaging also indicates an asymmetric elongation of the central isophotes in the same region. We use spherical orbit-superposition models to interpret the kinematics, using a set of orthogonal ``eigenVPs'' that allow us to fit models directly to spectra. The models require a central black hole of mass $1.2_{-0.6}^{+0.5}\times 10^9{M}_{\odot }$, with a strongly tangentially biased orbit distribution in the inner 40pc.

19 pages, 9 figures. Accepted for publication in MNRAS. High resolution version available at http://www-astro.physics.ox.ac.uk/~rcwh/ngc1399.ps.gz