Physical origin of extremely metal poor galaxies through statistical analysis
Speaker: Nishigaki Moka
Abstract:
Even in metal-emriched nearby universe, there exist extremely metal poor galaxies (EMPGs; Z < 0.1 Zsun). The physical origin of these galaxies is not yet known, so we conduct several statistical analyses to get closer to their physical origin. First, since EMPGs are faint and poorly observed, we have developed a new searching method using machine learning to enlarge the sample size enough for statistical analysis. We have so far succeeded in adding one additional EMPG. Then by using ~100 EMPGs identified in previous studies, we investigate the positions of these galaxies in the large-scale structure in relation to the sources that trigger star formation. Next, we calculate the cross-correlation functions to further quantify the clustering of EMPGs. Furthermore, by drawing the mass-metallicity relation and fundamental metallicity relation of EMPGs, we discuss whether they are close to equilibrium between inflows and outflows, comparing them with a simple chemical evolution model. Our analyses suggests that EMPGs are just beginning to experience metal enrichment by a burst of star formation.