부산대학교 도서관

The role of type Ia supernovae, mainly the Delay Time Distributions (DTDs) determined by the binary systems, and the yields of elements created by different explosion mechanisms, are studied by using the {\sc MulChem} chemical evolution model, applied to our Galaxy. We explored 15 DTDs, and 12 tables of elemental yields produced by different SN Ia explosion mechanisms, doing a total of 180 models. Chemical abundances for $\alpha$-elements (O, Mg, Si, S, Ca) and Fe derived from these models, are compared with recent observational data of $\alpha$-elements over Iron relative abundances, [X/Fe]. These data have been compiled and binned in 13 datasets. By using a $\chi^2$-technique, no model is able to fit simultaneously these datasets. A model computed with the 13 individual best models is good enough to reproduce them. Thus, a power law with a logarithmic slope $\sim -1.1$ and a delay in the range $\Delta \tau=40 --350$ Myr is a possible DTD, but a combination of several channels is more probable. Results of this average model for other disc regions show a high dispersion, as observed, which might be explained by the stellar migration. The dispersion might also come from a combination of DTDs or of explosion channels. The stellar migration joined to a combination of scenarios for SNIa is the probable cause of the observed dispersion.
Comment: submitted to MNRAS as main tex and appendix, here we send the whole text in 31 pages, by including Appendix that will be as Supporting Information in the publication