Super Star Clusters in Luminous Infrared Galaxies: the SUNBIRD Survey

TL;DR

This study investigates super star clusters in luminous infrared galaxies using adaptive optics imaging, revealing their luminosity functions, correlations with star formation rates, and implications for galaxy evolution.

Contribution

It provides the first statistically significant near-IR luminosity functions of SSCs in LIRGs and explores their relation to galaxy star formation activity.

Findings

LIRGs have shallower SSC luminosity function slopes than quiescent galaxies.

The brightest cluster luminosities correlate with host galaxy star formation rates.

Evidence suggests a physical cutoff in cluster luminosity/mass functions.

Abstract

We present recent results from an adaptive optics imaging survey of 40 Luminous IR Galaxies (LIRGs) searching for obscured core collapse supernovae and studying the galaxies themselves. Here, in particular, we discuss the Super Star Clusters (SSC) populations in the LIRGs. We have constructed the first statistically significant samples of Luminosity Functions (LF) of SSCs in the near-IR, and find evidence that the LF slopes in LIRGs are shallower than in more quiescent spiral galaxies. Distance and blending effects were investigated in detail paving the way for SSC studies further out than done previously. We have also correlated the luminosities of the brightest clusters with the star formation rates (SFR) of the hosts. The relation is similar, though somewhat steeper than that found in the optical and at lower SFR levels, suggesting systematic extinction and/or age effects. We find that the characteristics of the relation suggest an underlying physical driver rather than solely a size-of-sample effect. In particular, a truncated luminosity/mass function would naturally explain the small scatter we find. Finally, we are modelling the ages and masses of our near-IR detected clusters in conjunction with HST optical data and present early results of using SSC properties to trace the histories of the target LIRG systems.