The abundance pattern of o, ne, mg, and fe in the interstellar medium of s0 galaxy ngc 4382 observed with suzaku

Abstract

We derived the O, Ne, Mg, and Fe abundances in the interstellar medium (ISM) of a relatively isolated SO galaxy, NGC 4382, observed with the Suzaku XIS instruments, and compared the O/Ne/Mg/Fe abundance pattern with that of the ISM in elliptical galaxies. The derived temperature and Fe abundance in the ISM are ∼ 0.3 keV and 0.6-2.9 solar, respectively. The abundance ratios are derived with considerable accuracy than the abundances, themselves; that is, the O/Fe, Ne/Fe, and Mg/Fe ratios are 0.3, 0.7, and 0.6 in solar units, respectively. The O/Fe ratio is smaller than those of the ISM in elliptical galaxies (NGC 720, NGC 1399, NGC 1404, and NGC 4636) observed with Suzaku. Since O, Ne, and Mg are predominantly synthesized by supernovae (SNe) of type II, the observed abundance pattern indicates that the contribution of SN la products is higher in the S0 galaxy than in the elliptical galaxy. Since the hot ISM in early-type galaxies is an accumulation of stellar mass and SN la products, the low O/Fe ratio in the ISM of NGC 4382 reflects a higher rate of present SNe la, or stars containing more SN la products than those in elliptical galaxies. © 2010. Astronomical Society of Japan.