Rise-times of Core-Collapse Supernovae

Abstract

A supernova is the explosive end of a star. If the star is a white dwarf in a binary system, the supernova will be a thermonuclear or type Ia supernova. On the other hand, if the dying star is a massive star, the supernova will be a core-collapse supernova. In this kind of supernova, the star's core collapses under its own gravity after the fusion chain in its core reaches iron because its fusion consumes rather than generates energy. This collapse releases large amounts of energy. The collapse and the radioactive isotopes produced in the explosion power the supernova to emit radiation that we can observe. Core-collapse supernovae and their photometry are the main focus of this thesis. When the luminosity of a supernova is observed over time, the observations can be used to plot the supernova's light curve. By studying the light curve, the time from the explosion to the peak luminosity, i.e., the rise-time, can be determined. In this thesis, a sample of supernovae was studied and their rise-times investigated. Different supernova types evolve differently, so their rise-times also vary. Supernova rise-times can help in the investigation of progenitor characteristics, which are still not fully understood. Similarly, the understanding of the explosion mechanisms is still incomplete. This thesis aims to give some insight into the rise-times of core-collapse supernovae of different subtypes. Both stripped-envelope (Ib, Ibn, Ic, Ic-BL) and hydrogen rich (II, IIn) as well as the intermediate type (IIb) are studied. In addition to the rise-times, peak magnitudes and a subsample of more peculiar supernovae are identified. The peak magnitudes are plotted against rise-times to find possible correlations. The peculiar subsample offers a peek at the diversity of supernova light curve shapes, which could motivate further research.