Expanding on the fundamental metallicity relation in dwarf galaxies with MUSE

Bulichi, Teodora-Elena; Fahrion, Katja; Mernier, François; Hilker, Michael; Leaman, Ryan; Lyubenova, Mariya; Müller, Oliver; Neumayer, Nadine; Martin-Navarro, Ignacio; Pinna, Francesca; Rejkuba, Marina; Scholz-Diaz, Laura; van de Ven, Glenn
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Astronomy and Astrophysics

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The mass-metallicity relation (MZR) represents one of the most important scaling relations in the context of galaxy evolution, comprising a positive correlation between stellar mass and metallicity (Z). The fundamental metallicity relation (FMR) introduces a new parameter into the dependence, namely, the star formation rate (SFR). While several studies have found that Z is anti-correlated with the SFR at a fixed mass, the validity of this statement has been questioned extensively and no widely accepted consensus has been reached thus far. With this work, we investigate the FMR in nine nearby, spatially resolved, dwarf galaxies, using gas diagnostics on integral-field spectroscopic data of the Multi Unit Spectroscopic Explorer (MUSE), pushing such investigations to lower galaxy masses and higher resolutions. We find that both the MZR and FMR exhibit different behaviours within different star-forming regions of the galaxies. We find that the SFR surface-density-and-metallicity anti-correlation is tighter in the low-mass galaxies of our sample. For all the galaxies considered, we find a SFR surface-density-and-stellar-mass surface-density correlation. We propose that the main reason behind these findings is connected to the accretion mechanisms of the gas fuelling star formation, namely: low-mass, metal-poor galaxies accrete pristine gas from the intergalactic medium, while in more massive and metal-enriched systems, the gas responsible for star formation is recycled from previous star-forming episodes.

Based on observation collected at the ESO Paranal La Silla Observatory, Chile, Prog. ID 0108.B-0904, 0104.D-0503, 0100.B-0116, and 095.B-0.532.

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Traces of Galaxy Formation: Stellar populations, Dynamics and Morphology
We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.
Martín Navarro