PhD Part A Exam by Jonatan Selsing – University of Copenhagen

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PhD Part A Exam by Jonatan Selsing

Title: "High energy space phenomena: A window to the dark universe"

Supervisor: Lise Christensen

Censor: Maximillan Stritzinger (Aarhus University)

Because of the vast expanse of the universe we live in, very little starlight reaches us from the environments furthest from us. To explore the region of space unavailable to us via direct detection, extremely energetic phenomena can be used to investigate the space between us and them, by illuminating the universe otherwise obscured. Gaining a thorough understanding of the physical processes at play in the high-energy events populating our universe is of prime importance because any signatures deviating from the intrinsic appearance of the object can be attributed to the intervening material and thus an indirect inference can be made about the dark universe. In this thesis I present some of the work I am involved with related to high-energy phenomena, specifically: Quasars (QSOs), Gamma-Ray Bursts (GRBs) and Supernovae (SNe). The work I present here consists of four projects I am involved with and the majority is still a work in progress. The work I have been doing is specifically on the average properties of the UV to near-infrared spectra of a selection of QSOs, the explosion environments of high-velocity ejecta core-collapse supernovae, the average optical afterglow of long-duration GRBs and the search for high-redshift, lensed SNe, including the quadruply lensed supernova, "SN Refsdal".