The Southern Photometrical Local Universe Survey (S-PLUS): Searching for Metal-poor Dwarf Galaxies

Abstract The metal content of a galaxy’s interstellar medium (ISM) reflects the interplay between different evolutionary processes, such as feedback from massive stars and the accretion of gas from the intergalactic medium. Despite the expected abundance of low-luminosity galaxies, the low-mass and low-metallicity regime remains relatively understudied. Since the properties of their ISM resemble those of early galaxies, identifying such objects in the Local Universe is crucial to understanding the early stages of galaxy evolution. We used the DR3 catalog of the Southern Photometric Local Universe Survey (S-PLUS) to select low-metallicity dwarf galaxy candidates based on color selection criteria typical of metal-poor, star-forming, low-mass systems. The final sample contains approximately 50 candidates. Spectral energy distribution fitting of the 12 S-PLUS bands reveals that ∼60% of the candidates are best fit by models with low stellar metallicities. We obtained long-slit observations with the Gemini Multi-Object Spectrograph to follow up on a pilot sample and confirm whether these galaxies have low metallicities. We find oxygen abundances in the range 7.28 < 12 + log(O/H) < 7.82 (4%–13% of the solar value), confirming their metal-poor nature. Most targets are outliers in the mass–metallicity relation, i.e., they display a low metal content relative to their observed stellar masses. In some cases, perturbed optical morphologies might give evidence of dwarf-dwarf interactions or mergers. These results suggest that the low oxygen abundances may be associated with an external event causing the accretion of metal-poor gas, which dilutes the oxygen abundance in these systems.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-11-27
DOI
https://doi.org/10.3847/1538-4357/ae1116
Primary Topic
Galaxies: Formation, Evolution, Phenomena
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article
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article

The Southern Photometrical Local Universe Survey (S-PLUS): Searching for Metal-poor Dwarf Galaxies

Círia Lima-Dias, Ana L. Chies-Santos, W. Schoenell, Guilherme Limberg et al.
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
article

The Southern Photometrical Local Universe Survey (S-PLUS): Searching for Metal-poor Dwarf Galaxies

Círia Lima-Dias, Ana L. Chies-Santos, W. Schoenell, Guilherme Limberg, A. C. Krabbe, Thiago S. Gonçalves, A. R. Lopes, C. E. Ferreira Lopes, M. E. De Rossi, T. Ribeiro, S. Torres-Flores, P. K. Humire, J. A. Hernández-Jiménez, L. A. Gutiérrez-Soto, Luis Lomelí-Núñez, Eduardo Telles, C. Mendes de Oliveira, G. B. Oliveira Schwarz, F. R. Herpich, A. Kanaan, M. Grossi, Leandro Sampaio Oliveira Ribeiro, Denise R. Gonçalves, Amanda E. Araujo-Carvalho, A. V. Smith Castelli
article en

Abstract

Abstract The metal content of a galaxy’s interstellar medium (ISM) reflects the interplay between different evolutionary processes, such as feedback from massive stars and the accretion of gas from the intergalactic medium. Despite the expected abundance of low-luminosity galaxies, the low-mass and low-metallicity regime remains relatively understudied. Since the properties of their ISM resemble those of early galaxies, identifying such objects in the Local Universe is crucial to understanding the early stages of galaxy evolution. We used the DR3 catalog of the Southern Photometric Local Universe Survey (S-PLUS) to select low-metallicity dwarf galaxy candidates based on color selection criteria typical of metal-poor, star-forming, low-mass systems. The final sample contains approximately 50 candidates. Spectral energy distribution fitting of the 12 S-PLUS bands reveals that ∼60% of the candidates are best fit by models with low stellar metallicities. We obtained long-slit observations with the Gemini Multi-Object Spectrograph to follow up on a pilot sample and confirm whether these galaxies have low metallicities. We find oxygen abundances in the range 7.28 < 12 + log(O/H) < 7.82 (4%–13% of the solar value), confirming their metal-poor nature. Most targets are outliers in the mass–metallicity relation, i.e., they display a low metal content relative to their observed stellar masses. In some cases, perturbed optical morphologies might give evidence of dwarf-dwarf interactions or mergers. These results suggest that the low oxygen abundances may be associated with an external event causing the accretion of metal-poor gas, which dilutes the oxygen abundance in these systems.

The Astrophysical JournalVol. 994(2)
Universidade Federal do Rio Grande do Sul (BR), Consejo Nacional de Investigaciones Científicas y Técnicas (AR), Universidade Presbiteriana Mackenzie (BR), University of Atacama (CL), Universidad de Buenos Aires (AR), University of Chicago (US), Universidade Federal de Santa Catarina (BR), TMT Observatory (US), Valongo Observatory (BR), Millennium Institute of Astrophysics (CL), Universitaria de Investigación y Desarrollo (CO), National Observatory (BR), Institute of Astronomy and Space Physics (AR), Instituto de Geofísica y Astronomía (CU), Laboratório Nacional de Astrofísica (BR), Fundación Ciencias Exactas y Naturales (AR), University of La Serena (CL), Universidad Nacional de La Plata (AR)
Openalex Percentile: Top 75%
Galaxies: Formation, Evolution, Phenomena
DOIOpen Access PDFOpenAlex
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