Unfolding the early Universe with JWST

How did galaxies form and evolve into the structures we see in the Local Universe? Answering this question is one of the key goals in modern astronomy. Understanding the Universe as we observe it today requires investigating its origins and evolution across cosmic time. 

In his PhD thesis, Pierluigi Rinaldi made use of space-based telescopes to study how galaxies evolved across cosmic time. Rinaldi shows that starburst galaxies played an important role in assembling stellar mass in the early Universe. He demonstrates how low-stellar-mass galaxies preferentially grow through bursty episodes of star formation, while massive galaxies build their stellar mass through secular processes as early as one billion years after the Big Bang. 

Furthermore, Rinaldi highlights how the advent of James Webb Space Telescope (JWST) has radically transformed our view of the early Universe, enabling an unprecedented study of the Epoch of Reionization. He shows that young, low-stellar-mass galaxies undergoing violent episodes of star formation were likely primary agents of Cosmic Reionization. Building on this, Rinaldi concludes that galaxies with bursty star formation contributed more significantly to this process. 

Finally, Rinaldi presents the discovery of the first NIRCam-dark source and explores the possible nature of this exotic object. Rinaldi also presents a unique MIRI extremely red object, and discusses potential explanations for its nature. 

Dissertation: https://hdl.handle.net/11370/5a6b3d2e-d0ff-4352-b952-a011dbbadc4b