From local chemical evolution to cosmic chemical evolution

Abstract

My scientific life with Keith began about twenty five years ago with the study of the chemical evolution of light elements :cosmological elements D, He3, He4 and Li7 and spallative elements, LiBeB. Recently, major CMB results coming from WMAP and Planck, and observations of the total luminosity density leading to significant progress in establishing the star formation rate (SFR) at high redshift, led us to study in detail primordial stars say, Pop III stars, and their different properties (mass and associated nucleosynthesis, related ionizing power..), all that in a cosmological context. Presently, I will present the global cosmic chemical evolution within the framework of hierarchical formation of structures, in a merger tree context, to have a look at the early universe: reionization of the Universe, gamma ray burst and correlation with high z SFR, metal dispersion in DLAs... Finally, the discovery of gravitational waves coming from binary black holes mergers opens a new astrophysical window and we can, thanks to our nucleosynthetic approach, give some constraints on the cosmic binary compact object merger rates and associated stochastic gravitational background