The Origin of Intergalactic Light in Compact Groups of Galaxies

TL;DR

This study explores the origin of intergalactic light in compact galaxy groups, linking it to galaxy interactions and mergers that influence X-ray source populations and star formation activity.

Contribution

It provides evidence that intergalactic light formation is associated with galaxy interactions, mergers, and subsequent star formation quenching in compact groups.

Findings

Groups with IGL show marginally more ULXs.

Lower luminosity HMXRBs indicate reduced star formation.

IGL presence correlates with later evolutionary stage.

Abstract

We investigate the origin of intergalactic light (IGL) in close groups of galaxies. IGL is hypothesized to be the byproduct of interaction and merger within compact groups. Comparing the X-ray point source population in our sample of compact groups that have intergalactic light with compact groups without IGL, we find marginal evidence for a small increase in ultra-luminous X-ray sources (ULXs). There is also a significant bias towards lower luminosity high mass X-ray binaries (HMXRBs). We interpret this as an indication that groups with visible IGL represent a later evolutionary phase than other compact groups. They have galaxies characterized by quenching of star formation (lower star formation rate (SFR) inferred from lower HMXRB luminosity) after stellar material has been removed from the galaxies into the intergalactic medium, which is the source of the IGL. We conclude that the presence of an increased fraction of ULXs is due to past interaction and mergers within groups that have IGL.