Type Ia Supernova Explosion Models

Abstract

Because calibrated light curves of Type Ia supernovae have become a major tool to determine the local expansion rate of the Universe and also its geometrical structure, considerable attention has been given to models of these events over the past couple of years. There are good reasons to believe that perhaps most Type Ia supernovae are the explosions of white dwarfs that have approached the Chandrasekhar mass, M_ch ~ 1.39 M_sun, and are disrupted by thermonuclear fusion of carbon and oxygen. However, the mechanism whereby such accreting carbon-oxygen white dwarfs explode continues to be uncertain. Recent progress in modeling Type Ia supernovae as well as several of the still open questions are addressed in this review. Although the main emphasis will be on studies of the explosion mechanism itself and on the related physical processes, including the physics of turbulent nuclear combustion in degenerate stars, we also discuss observational constraints.Comment: 38 pages, 4 figures, Annual Review of Astronomy and Astrophysics, in pres

The Advanced Compton Telescope mission

“…Thermonuclear supernovae are also grand experiments in reactive hydrodynamical flows. We do not understand how the nuclear flame propagates, how it proceeds as fast as it does, or how and when it turns into a shock (or even whether, though there is some evidence that it does) and propagates supersonically [42]. We do not know to what extent instabilities break spherical symmetry, or whether their effects are wiped out by subsequent burning if they do.…”

Optical Light Curves of Supernovae

“…The incineration of a white dwarf, which is the most favored model today (see, e.g., [47,123]), does not predict an observable shock breaking out at the surface. The rise in brightness is due to the increase in size of the ejecta and lasts for almost three weeks [1,23,42,93] with the color and temperature rather constant.…”

Hot Stars: Old-Fashioned or Trendy?

“…Unfortunately, at present, we do not have a clear picture of the exact physical processes which take place in a SN Ia explosion and how the radiation released from it should be treated (for a recent review see Hillebrandt and Niemeyer 2000). In order to get an impression of the basic physics involved that affect the atmospheric structure of a SN Ia, a quick glance at an observed spectrum will help to point out the necessary steps for their further analysis.…”