UV excess and AGB evolution in elliptical-galaxy stellar populations

TL;DR

This paper investigates the connection between UV excess and AGB star properties in elliptical galaxies, using infrared surface brightness fluctuations to analyze unresolved stellar populations and shed light on the UV-upturn phenomenon.

Contribution

It introduces a method to link UV excess in elliptical galaxies with AGB evolution by analyzing infrared surface brightness fluctuations.

Findings

Hot HB stars are main contributors to UV luminosity excess.

Infrared surface brightness fluctuations effectively trace AGB properties.

Potential link between UV excess and AGB star characteristics in early-type galaxies.

Abstract

The puzzling origin of the ``UV-upturn'' phenomenon, observed in some elliptical galaxies, has recently been settled by identifying hot HB stars as main contributors to galaxy ultraviolet luminosity excess. While a blue HB morphology seems a natural characteristic of metal-poor stellar populations, its appearence in metal-rich systems, often coupled with a poorer rate of planetary nebulae per unit galaxy luminosity, might be calling for an intimate connection between UV excess and AGB properties in early-type galaxies. In this work, we want to briefly assess this issue, relying on infrared surface brightness fluctuations as a powerful tool to trace AGB properties in external galaxies with unresolved stellar populations.