Revaz, Y. and Jablonka, P. and Sawala, T. and Hill, V. and Letarte, B. and Irwin, M. and Battaglia, G. and Helmi, A. and Shetrone, M. D. and Tolstoy, E. and Venn, K. A. (2009) The dynamical and chemical evolution of dwarf spheroidal galaxies. Astronomy and Astrophysics, 501 (1). pp. 189-206. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20090914-095147649
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We present a large sample of fully self-consistent hydrodynamical Nbody/Tree-SPH simulations of isolated dwarf spheroidal galaxies (dSphs). It has enabled us to identify the key physical parameters and mechanisms at the origin of the observed variety in the Local Group dSph properties. The initial total mass (gas + dark matter) of these galaxies is the main driver of their evolution. Star formation (SF) occurs in series of short bursts. In massive systems, the very short intervals between the SF peaks mimic a continuous star formation rate, while less massive systems exhibit well separated SF bursts, as identified observationally. The delay between the SF events is controlled by the gas cooling time dependence on galaxy mass. The observed global scaling relations, luminosity-mass and luminosity-metallicity, are reproduced with low scatter. We take advantage of the unprecedentedly large sample size and data homogeneity of the ESO Large Programme DART, and add to it a few independent studies, to constrain the star formation history of five Milky Way dSphs, Sextans, LeoII, Carina, Sculptor and Fornax. For the first time, [Mg/Fe] vs. [Fe/H] diagrams derived from high-resolution spectroscopy of hundreds of individual stars are confronted with model predictions. We find that the diversity in dSph properties may well result from intrinsic evolution. We note, however, that the presence of gas in the final state of our simulations, of the order of what is observed in dwarf irregulars, calls for removal by external processes.
|Additional Information:||© ESO 2009. Received 27 January 2009 / Accepted 17 April 2009. We thank the anonymous referee for his constructive comments. As to the simulations, the data reduction and galaxy maps have been performed using the parallelized Python pNbody package (http://obswww. unige.ch/~revaz/pNbody/). This work was supported by the Swiss National Science Foundation.|
|Subject Keywords:||galaxies: dwarf; galaxies: evolution; galaxies: formation|
|Official Citation:||The dynamical and chemical evolution of dwarf spheroidal galaxies Y. Revaz, P. Jablonka, T. Sawala, V. Hill, B. Letarte, M. Irwin, G. Battaglia, A. Helmi, M. D. Shetrone, E. Tolstoy and K. A. Venn A&A 501 (1) 189-206 (2009) DOI: 10.1051/0004-6361/200911734.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||15 Sep 2009 15:42|
|Last Modified:||26 Dec 2012 11:22|
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