Grand Challenges in Milky Way and Galaxies

This paper describes the framing of three challenges in Galactic and extra-galactic astronomy that can be legitimately called “grand:” the expansion of the redshift frontier, the census of galaxies and of their constituents with a full understanding of galactic evolution, and the study of accretion onto supermassive black holes in galactic nuclei, whose event horizon is literally a physical frontier of the Universe and where there is a potential for the development of new physics