The chemical evolution of dwarf spheroidal galaxies: dissecting the inner regions and their stellar populations |
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| Authors: | A Marcolini A D'Ercole G Battaglia B K Gibson |
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| Institution: | Centre for Astrophysics, University of Central Lancashire, Preston, Lancashire PR1 2HE;Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy;Kapteyn Institute, University of Groningen, Postbus 800, 9700AV Groningen, the Netherlands;European Organization for Astronomical Research in the Southern Hemisphere, K.-Schwarzschild-Str. 2, 85748, Garching, Germany;School of Physics, University of Sydney, NSW 2006, Australia |
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| Abstract: | Using three-dimensional hydrodynamical simulations of isolated dwarf spheroidal galaxies (dSphs), we undertake an analysis of the chemical properties of their inner regions, identifying the respective roles played by Type Ia supernovae (SNe Ia) and Type II supernovae (SNe II). The effect of inhomogeneous pollution from SNe Ia is shown to be prominent within two core radii, with the stars forming therein amounting to ～20 per cent of the total. These stars are relatively iron-rich and α-element depleted compared to the stars forming in the rest of the galaxy. At odds with the projected stellar velocity dispersion radial profile, the actual three-dimensional one shows a depression in the central region, where the most metal-rich (i.e. Fe/H]-rich) stars are partly segregated. This naturally results in two different stellar populations, with an anticorrelation between Fe/H] and velocity dispersion, in the same sense as that observed in the Sculptor and Fornax dSphs. Because the most iron-rich stars in our model are also the most α depleted, a natural prediction and test of our model is that the same radial segregation effects should exist between α/Fe] and velocity dispersion. |
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| Keywords: | hydrodynamics stars: abundances galaxies: abundances galaxies: dwarf galaxies: evolution Local Group |
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