The DECam MAGIC Survey: A Wide-field Photometric Metallicity Study of the Sculptor Dwarf Spheroidal Galaxy

2025/04/04 by Barbosa, Fabrícia O., Chiti, Anirudh, Limberg, Guilherme +26 · 6 citations
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR)

paper · doi:10.48550/arxiv.2504.03593

Abstract

The metallicity distribution function and internal chemical variations of a galaxy are fundamental to understand its formation and assembly history. In this work, we analyze photometric metallicities for 3883 stars over seven half-light radii (\rm r_h) in the Sculptor dwarf spheroidal (Scl dSph) galaxy, using new narrow-band imaging data from the Mapping the Ancient Galaxy in CaHK (MAGIC) survey conducted with the Dark Energy Camera (DECam) at the 4-m Blanco Telescope. This work demonstrates the scientific potential of MAGIC using the Scl dSph galaxy, one of the most well-studied satellites of the Milky Way. Our sample ranges from \rm [Fe/H] ≈ - 4.0 to \rm [Fe/H] ≈ - 0.6, includes six new extremely metal-poor candidates (\rm [Fe/H] ≤ -3.0), and is almost three times larger than the largest spectroscopic metallicity dataset in the Scl dSph. Our spatially unbiased sample of metallicities provides a more accurate representation of the metallicity distribution function, revealing a more metal-rich peak than observed in the most recent spectroscopic sample. It also reveals a break in the metallicity gradient, with a strong change in the slope: from -3.26 ± 0.18 \rm dex/deg for stars inside ∼ 1 \rm r_h to -0.55 ± 0.26 \rm dex/deg for the outer part of the Scl dSph. Our study demonstrates that combining photometric metallicity analysis with the wide field of view of DECam offers an efficient and unbiased approach for studying the stellar populations of dwarf galaxies in the Local Group.

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Cited by

• Ultra-Faint Milky Way Satellites Discovered in Carina, Phoenix, and Telescopium with DELVE Data Release 3
• HSTPROMO Internal Proper Motion Kinematics of Dwarf Spheroidal Galaxies: II. Velocity Anisotropy and Dark Matter Cusp Slope of Sculptor
• A second-generation star in a relic dwarf galaxy
• Recent Advances in Understanding R-Process Nucleosynthesis in Metal-Poor Stars and Stellar Systems

Related

• The DECam MAGIC Survey: Spectroscopic Follow-up of the Most Metal-Poor Stars in the Distant Milky Way Halo
• Stellar Metallicities from DECam u-band Photometry: A Study of Milky Way Ultra-Faint Dwarf Galaxies
• The Southern Photometrical Local Universe Survey (S-PLUS): searching for metal-poor dwarf galaxies
• Metallicity Distribution Functions of 13 Ultra-Faint Dwarf Galaxy Candidates from Hubble Space Telescope Narrowband Imaging
• The Extreme Ends of the Metallicity Distribution in dSph Galaxies