Research highlights

Chemical evolution model of the Milky Way, M31 disks, nearby spirals and the local spiral population

Based on our pioneer chemical evolution model of the Milk Way(Chang et al. 1999, Hou et al. 2000), we further studied and compared the chemical evolution of the disks of the Milky Way (MW) and of Andromeda (M31), in order to reveal common points and differences between the two major galaxies of the Local group. We use a large set of observational data for M31, including recent observations of the Star Formation Rate (SFR) and gas profiles, as well as stellar metallicity distributions along its disk. We show that, when expressed in terms of the corresponding disk scale lengths, the observed radial profiles of MW and M31 exhibit interesting similarities, suggesting the possibility of a description within a common framework. We find that the profiles of stars, gas fraction and metallicity of the two galaxies, as well as most of their global properties, are well described by our model, provided the star formation efficiency in M31 disk is twice as large as in the MW(Fig D1, Yin et al. 2009). Our chemical model has been successfully applied to the other individual local spirals, e.g. M33(Kang et al. 2012), UGC8802(Chang et al. 2012). Moreover, we further developed and applied this model to the whole local spiral populations (Chang et al.) and also embedded it in the semi-analytic models (SAMs) of galaxy formation and evolution(e.g, Fu et al. 2012, 2013).

CE

Figure 1. Current profiles of gas, stars, SFR, gas fraction, and oxygen abundance for MW and M31. Observations are presented as shaded areas and model results by solid (for the MW) and dashed (for M31) curves, respectively.