First stars, galaxies, and black holes: now and then

Understanding the nature of the first cosmic sources is one of the key questions of Cosmology and Galaxy Formation. During the last years Cosmic Archaeology has opened the possibility to indirectly study these distant sources by catching their living fossils in the Local Universe.

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The physics of first star and galaxy formation

The formation of the first stars, black holes and galaxies is at the frontier of modern astrophysical research. Precision cosmology has revealed that we live in a flat Universe dominated by Dark Energy and Cold Dark Matter. Within this standard paradigm, structure formation proceeds hierarchically forming low mass objects first and subsequently building up larger galaxies all the way up to clusters of galaxies. While the growth of dark matter haloes is driven by gravity and well understood, the baryonic physics governing the formation and growth of stars, black holes and galaxies is more complex and requires the combination of different areas of physics covering such small scales as nuclei all the way up to parsec scale hydrodynamic instabilities. 

How initial stars and galaxies formed

A simulation of a galaxy formation. Credit: Jason Tumlinson

Un gruppo di astronomi che si dedicano allo studio delle condizioni fisiche dell’Universo primordiale hanno ottenuto nuovi indizi sui processi di formazione delle prime strutture cosmiche, cioè stelle e galassie, andando ad analizzare la composizione chimica di alcune ‘stelle fossili’ che sono distribuite nelle regioni più esterne ed interne dell’alone galattico.