Three dimensional simulations of rotating core collapse supernovae

• Main Author: Telford, Rosie
• Published: University of Leicester 2005
• Subjects: 523.844650113
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426047

A core collapse supernova is the dramatic death of a massive star by core implosion and subsequent explosion. Massive stars are known to rotate appreciably, yet the vast majority of supernova simulations over the years have not included rotation or its effects.;It is thought that moderate stellar rotation could assist the supernova explosion by lowering the effective gravitational potential in the core. More rapid rotation could give rise to jets and/or bipolar explosions. At the most extreme rotation rates it is thought that gamma ray bursts (GRB) are produced. These bursts may be delayed or revived at late times as a result of the collapsing core becoming rotationally unstable and fragmenting.;In this thesis the effects of rotation on core collapse are studied. Sophisticated progenitor models with rotation rates of up to a significant fraction of Keplerian are used as the starting points for three dimensional simulations. The computational method of Smoothed Particle Hydrodynamics is used to follow the collapse until core "bounce", the point at which the collapse is halted.;It is shown that, before bounce, no instabilities occur even for the most rapid rotators. The maximum value obtained for the ratio of rotational to gravitational binding energy is around 0.13, just below the limit of 0.14 required for instability on a secular timescale. However, the more rapidly rotating models obtain interesting structures as they collapse. In these models the density distribution remains centrally peaked but is surrounded by a torus of centrifugally supported material, consistent with the collapsar model of GRB.;The gravitational wave signals emitted in collapse are also calculated. It is found that these are strongest for the slowly rotating models, in which the collapse is not slowed significantly. A supernova of this type in the Virgo galaxy cluster would be beyond the range of the current generation of gravitational wave detectors.