Current signatures and search for Pop. III stars in the Local Universe

Abstract

Recent numerical studies argue that low-mass stars can be formed even at zero-metallicity environment. These low-mass Population III(Pop.~III) stars are thought to be still shining and able to be observed in the Local Universe. Most low-mass Pop.~III stars are thought to be formed as secondary companions in binary systems. They can be escaped from their host mini-halos when their primary companions explode as supernovae. In this paper, we estimate the escape probability of the low-mass Pop.~III stars from their host mini-halos. We find that $\sim 100$ Pop.~III stars are expected. We also compute spatial distribution of these escaped Pop.~III survivors by means of the semi-analytic hierarchical chemical evolution model. Typically, they are distributed around $\sim 2$Mpc away from the Milky Way but 5 -- $35\%$ of the escaped stars fall into the Milky Way halo. These escaped Pop.~III stars are possibly detected by very large scaled surveys being planned.