Resolving the extended stellar halos of nearby galaxies: the wide-field PISCeS survey

TL;DR

This study uses wide-field imaging to explore the stellar halos of two nearby galaxies, revealing numerous faint satellites and substructures, which shed light on galaxy formation and accretion processes.

Contribution

First comprehensive survey of stellar halos around Centaurus A and Sculptor, discovering faint satellites and substructures, and providing data to test galaxy formation models.

Findings

Discovered ~20 faint satellites to date.

Identified streams and substructures in galaxy halos.

Provided detailed stellar content and halo shape analysis.

Abstract

In the wide-field Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), we investigate the resolved stellar halos of two nearby galaxies (the elliptical Centaurus A and the spiral Sculptor, D $\sim3.7$ Mpc) out to a projected galactocentric radius of 150 kpc with Magellan/Megacam. The survey has led to the discovery of $\sim$20 faint satellites to date, plus prominent streams and substructures in two environments that are substantially different from the Local Group, i.e. the Centaurus A group dominated by an elliptical and the loose Sculptor group of galaxies. These discoveries clearly attest to the importance of past and ongoing accretion processes in shaping the halos of these nearby galaxies, and provide the first census of their satellite systems down to an unprecedented $M_V<-8$. The detailed characterization of the stellar content, shape and gradients in the extended halos of Sculptor, Centaurus A, and their dwarf satellites provides key constraints on theoretical models of galaxy formation and evolution.