Abstract

Extremely metal-poor galaxies (XMPOs) are objects with a metallicity lower than 1/10 of the solar value (12+log(O/H) < 7.69). Quiescent XMPs are difficult to analyse because of their very low metallicity, but XMP starbursts in the local Universe are ideal sites to study scenarios of star-formation and galaxy evolution thought to be similar to the conditions of the primaval building blocks from which larger systems were formed in the primitive Universe.

The chemical analysis of these SF objects is crucial to identify them and to explore if their nature is that of truly young, unevolved objects or dwarf systems rejuvenated by the fall of pristine gas. In this talk, I will review some of the results of our group in this line of research by means of the exploration of large deep surveys (e.g. SDSS , zCOSMOS, VUDS ) and detailed optical spatially resolved observations of a well-known local sample (e.g. IFU observations of IZw18).