The baryonic halos of isolated elliptical galaxies

TL;DR

This study investigates the globular cluster systems and stellar halos of isolated elliptical galaxies to understand their formation history, revealing common GC bimodality, constant GC frequency, and merger-related halo structures.

Contribution

It provides new insights into the properties of isolated elliptical galaxies, highlighting similarities and differences with cluster ellipticals, especially in their globular cluster systems and stellar halos.

Findings

GC color bimodality is common in isolated ellipticals

GC specific frequency remains fairly constant across galaxy masses

Red fraction of GCs follows an inverted V trend with mass

Abstract

Without the interference of a number of events, galaxies may suffer in crowded environments (e.g., stripping, harassment, strangulation); isolated elliptical galaxies provide a control sample for the study of galaxy formation. We present the study of a sample of isolated ellipticals using imaging from a variety of telescopes, focusing on their globular cluster systems as tracers of their stellar halos. Our main findings are: (a) GC color bimodality is common even in the most isolated systems; (b) the specific frequency of GCs is fairly constant with galaxy mass, without showing an increase towards high-mass systems like in the case of cluster ellipticals; (c) on the other hand, the red fraction of GCs follows the same inverted V shape trend with mass as seen in cluster ellipticals; and (d) the stellar halos show low S\'ersic indices which are consistent with a major merger origin.