Experimental Astrophysics

We will present some of the techniques used nowadays to observe the Universe on different scales and epochs. The thermal history of the Universe will be introduced, together with several investigation methods related to the study of the cosmic microwave background, signature of the "Recombination era" that drives the Universe in the so-called "Dark ages". We will discuss the end of this epoch, as set by the "Cosmic reionization" process. In particular, (i) we will study constraints on the end of this process by means of absorption spectra towards luminous and distant sources; (ii) we will present the formation of chemical elements from primordial to stellar nucleosynthesis and how the observational study of their distribution and abundance in the diffuse gas can constrain galaxy formation and evolution processes; (iii) we will discuss the main sources responsible for the reionization and metal enrichment of the Universe (namely galaxies and accreting black holes); (iv) we will review the main observational techniques used to identify and characterize the first galaxies and quasars formed after the Big Bang, with special emphasis to multi-wavelength observational data (including gravitational waves) obtained with current state-of-the-art observatories (HST, ALMA, Chandra, LISA); (v) we will compare observational data of the intergalactic medium, galaxies, accreting super massive black holes with dedicated zoom-in cosmological hydrodynamical simulations.