Morphology and stellar populations of a candidate ultra-diffuse galaxy in early Euclid and Rubin imaging

TL;DR

This study analyzes a candidate ultra-diffuse galaxy using multi-wavelength data from Euclid and Rubin, revealing its morphology, stellar populations, and potential formation history, and demonstrating the future potential of these surveys for studying LSB galaxies.

Contribution

It presents the first detailed analysis of a UDG candidate using early Euclid and Rubin data, highlighting their capability to identify and characterize numerous LSB galaxies.

Findings

Galaxy is likely an ultra-diffuse galaxy at 50-60 Mpc.

Spectral energy distribution indicates recent star formation.

Euclid and Rubin will enable large-scale UDG studies.

Abstract

We present multi-wavelength imaging and analysis of a low surface brightness (LSB) dwarf galaxy in the Extended Chandra Deep Field South (ECDFS), SMDG0333094-280938, with particular emphasis on data from the Euclid space telescope and from the Vera C. Rubin Observatory. The galaxy is clumpy and blue, and appears to host globular clusters (GCs), suggesting a distance of ~50-60 Mpc which would make the dwarf an ultra-diffuse galaxy (UDG). We carry out spectral energy distribution (SED) fitting from the far-ultraviolet to the near-infrared, in order to estimate the galaxy age and metallicity. We infer a recent peak of star formation that may have led to the formation of the UDG through feedback-driven expansion. This early analysis illustrates how Euclid and Rubin are poised to identify and characterize many thousands of UDGs and other LSB galaxies in the near future, including their GCs and stellar populations.