Type Ia and II supernovae contributions to the metal enrichment in intra-cluster medium observed with Suzaku

TL;DR

This study uses Suzaku X-ray observations to measure metal masses in galaxy clusters and groups, estimating supernova contributions to ICM enrichment and comparing results with star formation rates.

Contribution

First precise measurement of ICM metal masses within specific radii, and estimation of supernova ratios contributing to metal enrichment in galaxy clusters and groups.

Findings

Supernova ratio (SNe II to SNe Ia) is approximately 3.5.

ICM metal mass measurements are consistent with supernova nucleosynthesis models.

The number of past SNe II is comparable to or exceeds star formation rates from Hubble Deep Field data.

Abstract

We studied the properties of the intra-cluster medium (ICM) in two clusters of galaxies (AWM 7 and Abell 1060) and two groups (HCG 62 and NGC 507) with the X-ray Observatory Suzaku. Based on spatially resolved energy spectra, we measured for the first time precise cumulative ICM metal masses within 0.1 and ~0.3 r_{180}. Comparing our results with supernova nucleosynthesis models, the number ratio of type II (SNe II) to type Ia (SNe Ia) is estimated to be ~3.5, assuming the metal mass in the ICM is represented by the sum of products synthesized in SNe Ia and SNe II. Normalized by the K-band luminosities of present galaxies, and including the metals in stars, the integrated number of past SNe II explosions is estimated to be close to or somewhat higher than the star formation rate determined from Hubble Deep Field observations.