Metallicity distribution of halo stars and minor merger processes of the Galaxy

A possible relation between the high dispersion in metallicity of metal-poor halo stars and the minor merger processes in the history of the Galaxy is presented. The foreign populations of stars in the satellites through minor merger processes, make considerable contributions to the Galactic halo, therefore alter the intrinsic distribution of metallicities of the halo stars. Our model reproduces the observed trends in the metallicity distribution of the extremely metal-poor halo field stars in the Galaxy. Taken all the parameters for our model, a density of $1.9\times 10^{-3}kpc^{-3}$ of extremely metal-poor halo stars in $-5<[Fe/H]<-4$ is predicted, which explains why no such stars have been observed so far.