Observational study of Core Collapse Supernovae

Abstract

The advent of dedicated surveys for studying transient events has invoked a great interest in the study of supernovae (SNe). The rate of discovery of SNe has hence gone up ten-fold relinquishing their diversity. SNe not only helps in probing the end stages of stellar evolution but also help in understanding the cosmic enrichment. SNe plays a significant role in driving the chemical and dynamical evolution of galaxies and have been proposed to be major contributors of dust when the Universe was young. SNe were initially classified into just two types: Type Ia and Type II. However, several decades of research have highlighted that their peculiarities can be depicted accurately only with the help of subclasses, namely Ia, Ib, Ic, Ic-BL, IIP, IIL, IIb, IIn and Ibn. The diversity is primarily driven by differences in the spectroscopic signatures of these objects and in some cases, the photometric features. Based on the explosion mechanisms, SNe are broadly classified into Thermo-nuclear supernovae and Core-collapse supernovae (CCSNe). CCSNe result from the gravitational collapse of the core in stars more massive than 8 Mand#8857;. All subclasses of SNe except Type Ia events are a result of core-collapse. The observational differences in the properties of various subclasses of CCSNe (even within a single subclass) is attributed to the mass, metallicity and environment of its progenitor. The temporal (i.e., light curve) and spectral evolution of a SN allow the inference of critical parameters related to the progenitor. This highlights the importance of studying individual SNe events. The aim of the work performed during the course of the thesis is to study the individual SNe in detail, infer explosion parameters and progenitor properties (such as 56Ni-mass, ejecta mass, explosion energy, and progenitor mass, radius, and metallicity) and understand their inherent peculiarities. This thesis consists of 7 chapters. Chapter 1 gives a generic introduction to supernovae, its classification scheme, and the explosion mechanism. Mass...