VST-SMASH: VST Survey of Mass Assembly and Structural Hierarchy I. Survey presentation and deep photometry of IC 5332: tracing the mass assembly in the challenging faintest-end regime

TL;DR

The VST-SMASH survey provides deep optical imaging to explore faint stellar features in late type galaxies, exemplified by detailed analysis of IC 5332 revealing accretion and assembly processes.

Contribution

This paper introduces the VST-SMASH survey and demonstrates its effectiveness in detecting and analyzing faint low surface brightness features in galaxy outskirts.

Findings

Detection of faint stellar streams around IC 5332.

Color gradients indicating accreted stellar populations.

Evidence of ongoing stellar mass assembly through accretion.

Abstract

Understanding the formation and evolution of late type galaxies (LTG) requires deep imaging for tracing the faintest stellar components in their outskirts. Despite their crucial role in the buildup of stellar mass, these low surface brightness (LSB) features remain largely unexplored due to observational limitations. The VST-SMASH is designed to fill this gap, providing deep, wide field optical imaging for a volume limited sample of nearby LTG, overlapping with the Euclid Wide Survey in the South. This paper aims to introduce the VST-SMASH survey and showcase its scientific potential through the analysis of IC 5332, a LTG observed in the g, r, and i bands. The main goal is to demonstrate the depth, quality, and diagnostic power of the dataset in tracing LSB features and structural components in galactic outskirts. We carried out detailed surface photometry of IC 5332 to extract radial surface brightness and color profiles down to LSB regime. We performed multicomponent Sersic decompositions and constructed stellar mass surface density profiles. We identified and characterized faint stellar streams, estimating their colors and comparing them with adjacent galactic regions. While the internal (1Reff) negative colour gradients can be explained by dissipative collapses and SN outflows, the color profiles at larger radii reveal a significant gradient toward redder colors, consistent with the presence of accreted populations in the outskirts. We also find bluer r - i, which could be explained by strong Ha emission. These findings support a scenario of ongoing stellar mass assembly through accretion and highlight the capability of VST-SMASH to uncover faint structures in nearby galaxies.(abridged)