SN Ia Enrichment in Virgo Early-type Galaxies from ROSAT and ASCA Observations

摘要: We analyzed nine X-ray-bright Virgo early-type galaxies observed by both ASCA and ROSAT. Through spatially resolved spectroscopy, we determined the radial temperature profiles abundances of Mg, Si, Fe for six galaxies. The are consistent with isothermal temperatures outside cooler regions at galaxies' centers. present new evidence iron abundance gradients in NGC 4472 4649 confirm previous results on 4636. Mg Si average flatter than those correspond to an underabundance α-process elements high values, while low element ratios favor enrichment Type II supernovae (SNe). explain trend using metallicity dependence SN Ia metal production constraints available theoretical modeling low-metallicity inhibition SNe Ia. Our imply a cutoff range 0.07-0.3 solar require lower limit 0.3 contribution estimate rate centers brightest our sample ~0.08 h SNU (supernova units). rates inferred from optical searches should be corrected presence "faint" events, since these release limited metals therefore do not contribute significantly measured X-ray gas. With this correction present-epoch is 0.10 ± 0.06 comparable estimates. A simple comparison shows that derive still discrepant optically values. attribute difference spatial resolution measurements, abundances, importance hydrodynamical effects, particularly inflow cooling gas, abundances.