The G-dwarf distribution in star-forming galaxies: a tug-of-war between infall and outflow

E. Spitoni, F. Calura, V. Silva Aguirre, R. Gilli

The G-dwarf distribution in star-forming galaxies: a tug-of-war between infall and outflow
See arXiv version
Accepted for publication in Astronomy and Astrophysics Letters (A&A Letters), 6 pages, 4 figures

 

Abstract

In the past, the cumulative metallicity distribution function (CMDF) turned out as a useful tool to constrain the accretion history of various components of the Milky Way. In this Letter, by means of analytical, leaky-box chemical evolution models (i.e. including both infall and galactic outflows) we study the CMDF of local star-forming galaxies that follow two fundamental empirical scaling relations, namely the mass-metallicity and main sequence relations. Our analysis shows that galactic winds, which are dominant mostly in low-mass systems, play a fundamental role in shaping this function and, in particular, in determining its steepness and curvature. We show that the CMDF of low-mass (M\(_{\star}\)/M\(_{\odot} \le 10^{9.5}\)) and high-mass (M\(_{\star}\)/M\(_{\odot}\)>10\(^{10.5}\)) galaxies deviate substantially from the results of a ‘closed-box’ model, as the evolution of the former (latter) systems is mostly dominated by outflows (infall). In the context of galactic downsizing, we show that downward-concave CMDFs (associated with systems with extremely small infall timescales and with very strong winds) are more frequent in low-mass galaxies, which include larger fractions of young systems and present more substantial deviations from equilibrium between gas accretion and reprocessing (either via star formation or winds).

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