%0 Generic %1 gargiulo2014chemoarcheological %A Gargiulo, I. D. %A Cora, S. A. %A Padilla, N. D. %A Arancibia, A. M. Muñoz %A Ruiz, A. N. %A Orsi, A. A. %A Tecce, T. E. %A Weidner, C. %A Bruzual, G. %D 2014 %K chemical evolution igimf %T Chemo-Archeological Downsizing in a Hierarchical Universe: Impact of a Top Heavy IGIMF %U http://arxiv.org/abs/1402.3296 %X We make use of a semi-analytical model of galaxy formation to investigate the origin of the observed correlation between a/Fe abundance ratios and stellar mass in elliptical galaxies.We implement a new galaxy-wide stellar initial mass function (Top Heavy Integrated Galaxy Initial Mass Function, TH-IGIMF) in the semi-analytic model SAG and evaluate its impact on the chemical evolution of galaxies. The SFR-dependence of the slope of the TH-IGIMF is found to be key to reproducing the correct a/Fe-stellar mass relation. Massive galaxies reach higher a/Fe abundance ratios because they are characterized by more top heavy IMFs as a result of their higher SFR. As a consequence of our analysis, the value of the minimum embedded star cluster mass, which is a free parameter involved in the TH-IGIMF theory, is found to be as low as 5 solar masses. A mild downsizing trend is present for galaxies generated assuming either a universal IMF or a variable TH-IGIMF.We find that, regardless of galaxy mass, older galaxies (with formation redshifts > 2) are formed in shorter time-scales (< 2Gyr), thus achieving larger a/Fe values. Hence, the time-scale of galaxy formation alone cannot explain the slope of the a/Fe-galaxy mass relation, but is responsible for the big dispersion of a/Fe abundance ratios at fixed stellar mass.

@misc{gargiulo2014chemoarcheological, abstract = {We make use of a semi-analytical model of galaxy formation to investigate the origin of the observed correlation between [a/Fe] abundance ratios and stellar mass in elliptical galaxies.We implement a new galaxy-wide stellar initial mass function (Top Heavy Integrated Galaxy Initial Mass Function, TH-IGIMF) in the semi-analytic model SAG and evaluate its impact on the chemical evolution of galaxies. The SFR-dependence of the slope of the TH-IGIMF is found to be key to reproducing the correct [a/Fe]-stellar mass relation. Massive galaxies reach higher [a/Fe] abundance ratios because they are characterized by more top heavy IMFs as a result of their higher SFR. As a consequence of our analysis, the value of the minimum embedded star cluster mass, which is a free parameter involved in the TH-IGIMF theory, is found to be as low as 5 solar masses. A mild downsizing trend is present for galaxies generated assuming either a universal IMF or a variable TH-IGIMF.We find that, regardless of galaxy mass, older galaxies (with formation redshifts > 2) are formed in shorter time-scales (< 2Gyr), thus achieving larger [a/Fe] values. Hence, the time-scale of galaxy formation alone cannot explain the slope of the [a/Fe]-galaxy mass relation, but is responsible for the big dispersion of [a/Fe] abundance ratios at fixed stellar mass.}, added-at = {2014-02-17T10:27:43.000+0100}, author = {Gargiulo, I. D. and Cora, S. A. and Padilla, N. D. and Arancibia, A. M. Muñoz and Ruiz, A. N. and Orsi, A. A. and Tecce, T. E. and Weidner, C. and Bruzual, G.}, biburl = {https://www.bibsonomy.org/bibtex/2922855c608164cc06d435b622a4b161a/miki}, description = {[1402.3296] Chemo-Archeological Downsizing in a Hierarchical Universe: Impact of a Top Heavy IGIMF}, interhash = {a81e15afad354b54f5421fee78b9c175}, intrahash = {922855c608164cc06d435b622a4b161a}, keywords = {chemical evolution igimf}, note = {cite arxiv:1402.3296Comment: 28 pages, 19 figures, 2 tables. (Comments most welcome). Summited to MNRAS}, timestamp = {2014-02-17T10:27:43.000+0100}, title = {Chemo-Archeological Downsizing in a Hierarchical Universe: Impact of a Top Heavy IGIMF}, url = {http://arxiv.org/abs/1402.3296}, year = 2014 }