An [ITAL]XMM-Newton[/ITAL] Observation of NGC 1399 Reveals Two Phases of Hot Gas and Supersolar Abundances in the Central Regions

We present an initial analysis of a new XMM-Newton observation of NGC 1399, the central elliptical galaxy of the Fornax group. Spectral fitting of the spatially resolved spectral data of the European Photon Imaging Camera MOS and pn CCDs reveals that a two-temperature (2T) model of the hot gas is favored over single-phase and cooling flow models within the central ~20 kpc. The preference for the 2T model applies whether or not the data are deprojected. The cooler component has a temperature (~0.9 keV) similar to the kinetic temperature of the stars, while the hotter component has a temperature (~1.5 keV) characteristic of the virial temperature of a ~10 13 M ☉ halo. The two-phase model (and other multitemperature models) removes the "Fe bias" within r ≲ 20 kpc and gives Z Fe / Z ☉ ≈ 1.5-2. At larger radii, the iron abundance decreases until Z Fe / Z ☉ ~ 0.5 for r ~ 50 kpc. The Si abundance is supersolar (1.2-1.7 solar) within the central regions, while Z Si / Z Fe ≈ 0.8 over the entire region studied. These Fe and Si abundances imply that ≈80% of the Fe mass within r ~ 50 kpc originates from Type Ia supernovae (SNe Ia). This SNe Ia fraction is similar to that inferred for the Sun and therefore suggests a stellar initial mass function similar to the Milky Way.