THE HEAVY ELEMENT ABUNDANCE IN THE HOT CORONA OF THE BRIGHT ELLIPTIC GALAXY NGC 4472

From a 25 ks ROSAT PSPC observation of the elliptical galaxy NGC 4472, we measured the iron abundance with arcminute spatial resolution to a radial distance of 16' (74 kpc) in the hot corona. The heavy element abundance is roughly constant at approximately 1-2 [Fe/H]. from 4' to 16'. A comparison of these measurements to models of the heavy element enrichment of hot galactic coronae around elliptical galaxies provides new insights and constraints for the evolution with time of the Type la supernova rate and for its present epoch value. In particular, the near-solar value of the iron abundance and its constancy throughout the corona suggest a relatively constant supernova rate over time with a present epoch value at the low end of the range derived by van den Bergh & Tammann.