Galaxy Size Reveals Connection Between Gas Inflow History and Metallicity
A new study analyzing 1,500 star-forming galaxies finds that galaxy size encodes information about long-term gas inflow histories, which directly influences metallicity levels. Researchers used optical spectroscopy and gas mass measurements to show that inner gas mass is the second-most important factor (after stellar mass) in predicting metallicity, challenging previous models. This discovery helps explain why galaxies with different sizes have different chemical compositions despite having similar stellar masses.
Using data from the MaNGA integral field spectroscopy survey, researchers analyzed approximately 1,500 star-forming galaxies to understand how galaxy properties relate to chemical abundances. They found that inner gas mass is the strongest predictor of metallicity after stellar mass, and that galaxy size correlates strongly with both inner gas mass and long-term inflow histories. The study challenges the idea that deeper gravitational potentials in more massive galaxies lead to higher metallicities; instead, more compact galaxies actually have lower dynamical masses. Chemical evolution models suggest that compact galaxies experienced earlier inflow histories, leading to lower current gas masses and more rapidly depleted gas reservoirs, which paradoxically results in higher metallicities. The research indicates that galaxy size encodes information about halo assembly histories and gas inflow patterns that shape chemical evolution over billions of years.
What different sources said
- arXiv astro-phCenter
Beyond the Fundamental Metallicity Relation: galaxy sizes encode the link between inflow and metallicity
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