The optical/X-ray connection: ICM iron content and galaxy optical luminosity in 20 galaxy clusters

TL;DR

This study investigates the relationship between iron content in the intra-cluster medium and galaxy luminosities in 20 galaxy clusters, highlighting the role of brightest cluster galaxies and supernovae in iron enrichment.

Contribution

It provides a systematic analysis linking ICM iron mass to BCG luminosity and estimates the contribution of SN Ia to the iron content, emphasizing the role of ram-pressure stripping.

Findings

ICM iron mass correlates better with BCG luminosity than with other galaxy populations.

SN Ia contribute over 50% of the iron in the ICM.

Ram-pressure plus tidal stripping enhance BCG luminosity and ICM iron mass.

Abstract

X-ray observations of galaxy clusters have shown that the intra-cluster gas has iron abundances of about one third of the solar value. These observations also show that part (if not all) of the intra-cluster gas metals were produced within the member galaxies. We present a systematic analysis of 20 galaxy clusters to explore the connection between the iron mass and the total luminosity of early-type and late-type galaxies, and of the brightest cluster galaxies (BCGs). From our results, the intra-cluster medium (ICM) iron mass seems to correlate better with the luminosity of the BCGs than with that of the red and blue galaxy populations. As the BCGs cannot produce alone the observed amount of iron, we suggest that ram-pressure plus tidal stripping act together to enhance, at the same time, the BCG luminosities and the iron mass in the ICM. Through the analysis of the iron yield, we have also estimated that SN Ia are responsible for more than 50% of the total iron in the ICM. This result corroborates the fact that ram-pressure contributes to the gas removal from galaxies to the inta-cluster medium, being very efficient for clusters in the temperature range 2 < kT (keV)< 10