Inhomogeneous Hot Gas in NGC 507
Session 49 -- Elliptical Galaxies
Display presentation, Wednesday, 1, 1994, 9:20-6:30

## [49.08] Inhomogeneous Hot Gas in NGC 507

D.-W. Kim and G. Fabbiano (SAO)

We present the X-ray properties of NGC 507 observed by the ROSAT PSPC and provide observational data of radial changes in X-ray emission and its emitting temperature which are critical to understand the nature of the X-ray emitting gas and to build theoretical cooling flow models. The X-ray emission is extended at least out to 1000 arcsec (480 kpc at a distance of 99.3 Mpc). The radial profile of X-ray surface brightness is $\Sigma_X \sim r^{-1.8}$ outside the core region. The radial profile is a function of energy such that the soft X-rays have a smaller core radius and a flatter slope. The spectral analysis reveals that the emission temperature peaks at the intermediate radius at 2-3 arcmin and falls both inward and outward. The absorption column density is consistent with the galactic line of sight value. The observed radial profile of X-ray surface brightness and emission temperature is qualitatively best matched to a model with the full Tammann's supernova rate, a large amount of heavy halo and mass sinks over a wide range of radii. Assuming hydrostatic equilibrium the estimated mass to light ratio is 76 $\pm$ 13, indicating large amount of heavy halo. Near the edge of the X-ray emitting region there are many faint sources and we discuss various possibilities of their nature.