Suzaku Observation of the Metallicity in the Interstellar Medium of NGC 4258

TL;DR

This study uses Suzaku X-ray data to analyze the interstellar medium of NGC 4258, revealing its temperature structure and metal abundances, which are similar to solar values, indicating comparable enrichment processes.

Contribution

First measurement of ISM metal abundances in NGC 4258 using Suzaku, confirming a two-temperature model and solar-like abundance patterns.

Findings

ISM temperatures are 0.23 and 0.59 keV.

Metal abundances of O, Ne, Mg, Si, Fe measured for the first time.

Abundance pattern aligns with solar values, suggesting similar enrichment processes.

Abstract

The Suzaku X-ray satellite observed the nearby spiral galaxy NGC 4258 for a total good exposure time of 100 ks. We present an analysis of the Suzaku XIS data, in which we confirm that the 0.5--2 keV spectra of the interstellar medium (ISM) are well-represented by a two-temperature model. The cool and hot ISM temperatures are 0.23+-0.02 and 0.59 +-0.01 keV, respectively. Suzaku's excellent spectral sensitivity enables us to measure the metal abundances of O, Ne, Mg, Si and Fe of the ISM for the first time. The resultant abundance pattern of O, Mg, Si, and Fe is consistent with that of the new solar abundance table of Lodders (2003), rather than Anders & Grevesse (1989). This suggests that the metal enrichment processes of NGC 4258 and of our Galaxy are similar.