The orbital structure of the massive elliptical galaxy NGC 5846

We use density and temperature profiles obtained from XMM-Newton observations to derive a potential of NGC 5846 out to 11 R(e), thus probing the mass distribution deep into the halo. The inferred circular velocity is significantly higher than the extrapolation of dynamical models implying a halo, more massive than previously thought. Using an I-band surface-brightness profile and a projected velocity dispersion profile consisting of long-slit kinematic measurements and planetary nebulae (PNe) velocity dispersions, we solve the Jeans equations, assuming a non-rotating spherical system. The solutions suggest a highly radially anisotropic galaxy outside 0.7R(e) with beta similar to 0.75. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim