SEAMLESS Survey: Four Faint Dwarf Galaxies Tracing Low-Mass Galaxy Evolution Across Environments

TL;DR

This paper presents the discovery and analysis of four faint dwarf galaxies across diverse environments, demonstrating the effectiveness of the SEAMLESS machine learning survey in studying low-mass galaxy evolution.

Contribution

It introduces four new dwarf galaxies identified through SEAMLESS, highlighting their varied evolutionary states and environmental contexts, and showcases the survey's capability to census faint galaxies beyond the Local Group.

Findings

Hydrus A is consistent with quenching by cosmic reionization or feedback.

LEDA 486718 is an isolated, star-forming dwarf galaxy.

Cetus B appears quenched and disturbed, possibly a satellite or backsplash galaxy.

Abstract

We report on four Local Volume dwarf galaxies identified through our ongoing SEmi-Automated Machine LEarning Search for Semi-resolved galaxies (SEAMLESS): Hydrus A, LEDA 486718, Cetus B, and Sculptor 26, with the discovery of Hydrus A reported here for the first time. These four galaxies span a wide range of environments and evolutionary states. Hydrus A (MV = -9.39+/-0.20, D = 3.38-0.30+0.32 Mpc) and LEDA 486718 (MV = -11.62+/-0.08, D = 4.80+/-0.17 Mpc) are among the most isolated dwarfs known within 5 Mpc, while Cetus B (MV = -8.26+/-0.17, D = 3.32-0.23+0.25 Mpc) and Sculptor 26 (MV = -11.25+/-0.10, D =3.21+/-0.13 Mpc) lie < 2 Rvir of NGC 253. Hydrus A shows properties consistent with quenching driven by cosmic reionization, cosmic-web interactions, or internal feedback. LEDA 486718 is an isolated star forming dwarf. Cetus B appears quenched and morphologically disturbed, making it a low-mass satellite or backsplash candidate, while Sculptor 26 is red and seemingly gas-poor but displays signs of recent activity, consistent with a transitional evolutionary state. Together, these systems demonstrate the power of SEAMLESS for building a census of faint galaxies beyond the Local Group.