15 March 2018


Carlos Gomez Guijarro

A thesis for the degree of Doctor of Philosophy defended May 2019.

The PhD School of Science, Faculty of Science,  Cosmic Dawn Center (DAWN), Niels Bohr Institute, University of Copenhagen

Prof. Sune Toft

Connecting the Extremes High-redshift Starbursts as Progenitors of Massive Galaxies

From our planet Earth, we have always been fascinated by the vastness of the cosmos. For centuries we have tried to unveil its nature, the physical laws, the origin of everything, and how we came to exist. The universe appears dark to our eyes with glimpses of light from distant stars like our Sun. Stellar di use conglomerations were revealed to be even more distant Worlds, galaxies like our Milky Way. As the timescales of galaxy formation and evolution are much longer than our lifespan, we cannot witness the evolution of galaxies directly. Fortunately, the nite speed of light allows us to observe how the universe looked like at di erent epochs just by observing at larger distances. Like the photograms of a movie we can reconstruct the evolution of galaxies. In our galactic neighborhood there is one type of galaxies that encodes the richest information of the evolution of galaxies in the universe, the giant elliptical galaxies. They are the most massive and largest galaxies known, void of star formation, so-called quiescent. Besides, they are the oldest. Their formation traces back to the earliest epochs of the universe. Understanding their origins and evolutionary sequence lead to the comprehension of the history of structures in the universe over 13 billion years. In my thesis, I studied distant galaxies characterized for their vigorous star formation, so-called starbursts, aiming at unveiling their roles as progenitors of massive galaxies and providing insight in the physical processes shaping galaxy formation and evolution. First, I discovered that these starbursts are capable of assembling large amounts of stars very rapidly in compact, dust-enshrouded regions. This matches with the physical characteristics of distant massive quiescent galaxies, establishing an evolutionary connection between them.

Second, I peered into the origin of the galaxy clusters where elliptical galaxies live in our nearby universe, tracing them back to their plausible progenitors as conglomerations of gas-rich, dusty star-forming galaxies. Third, I explored the transition between star-forming to quiescent galaxies, classifying galaxies based on fundamental star-forming and structural relations and applying physical diagnostics to assess their burstiness. I discovered that compact star-forming galaxies are consistent with being old starbursts on its way to quiescence. The work presented in this dissertation contributes to widening our understanding of the evolution of massive galaxies.

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