The Abundance Pattern of O, Ne, Mg, and Fe in the Interstellar Medium of S0 Galaxy NGC 4382 Observed with Suzaku

TL;DR

This study measures the elemental abundances in the interstellar medium of NGC 4382, revealing a higher contribution of Type Ia supernovae compared to elliptical galaxies, which impacts our understanding of galaxy evolution.

Contribution

First detailed measurement of O, Ne, Mg, and Fe abundances in the ISM of an S0 galaxy, comparing to elliptical galaxies to understand supernova contributions.

Findings

O/Fe ratio is lower than in elliptical galaxies.

Higher SN Ia contribution inferred in NGC 4382.

ISM temperature is about 0.3 keV with Fe abundance 0.6--2.9 solar.

Abstract

We derived O, Ne, and Mg abundances in the interstellar medium (ISM) of a relatively isolated S0 galaxy, NGC 4382, observed with the Suzaku XIS instruments and compared the O/Ne/Mg/Fe abundance pattern to those of the ISM in elliptical galaxies. The derived temperature and Fe abundance in the ISM are about 0.3 keV and 0.6--2.9 solar, respectively. The abundance ratios are derived with a better accuracy than the abundances themselves: O/Fe, Ne/Fe, and Mg/Fe ratios are 0.3, 0.7, and 0.6, respectively, in solar units. The O/Fe ratio is smaller than that 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 Ia products is higher in the S0 galaxy than in the elliptical galaxies Since the hot ISM in early-type galaxies is an accumulation of stellar mass and SN Ia products, the low O/Fe ratio in the ISM of NGC 4382 reflects a higher rate of present SNe Ia, or stars containing more SN Ia products than those in elliptical galaxies.