Planetary nebulae as tracers of accreted stellar populations in massive galaxies in groups and clusters

TL;DR

This paper reviews how planetary nebulae serve as tools to trace the assembly of stellar populations in galaxy groups and clusters, highlighting recent observational and theoretical advances.

Contribution

It synthesizes current knowledge on planetary nebulae as tracers of stellar populations and discusses future prospects with upcoming instrumentation.

Findings

PN metrics reveal differences between in-situ and ex-situ stellar populations.

Integral-field spectroscopy enhances understanding of PN and stellar properties.

Revised stellar evolution models improve agreement with extragalactic PN observations.

Abstract

Planetary nebulae (PNe) are valuable spatial and kinematic tracers of nearby galaxies. In this mini-review, I focus on their role in tracing the halo and intra-cluster/intra-group light assembly in groups and clusters of galaxies within 100~Mpc and, in particular, the link between characteristic PN metrics such as the $\alpha$-parameter and the PN luminosity function and changes from the underlying in-situ to ex-situ stellar populations. These results from nearby groups and clusters are placed into context with integral-field spectroscopic surveys of galaxies, which allow the co-spatial measurement of PN and stellar population properties. I provide an outlook on upcoming instrumentation that will provide new opportunities for the study of extragalactic PN populations. I address the challenges of reconciling observations of extragalactic PN populations with predictions from stellar evolution models and how revised late-stellar-evolution models have alleviated some of the tensions between observations and theory.