Brightness distribution of violent WD mergers. Black solid histogram shows all CO WD mergers from population synthesis, while coloured histogram lines show the brightness distributions when more stringent mass ratio constraints are assumed. Grey scale shows the observational peak brightness distribution of 74 SNe Ia from the volume-limited sample of Li et al.; observations are scaled up to enable comparison with the distribution shapes from our models.

In a recent paper (Monthly Notices of the Royal Astronomical Society, Volume 429, Issue 2, p.1425-1436, 2013), we investigate the brightness distribution expected for violent mergers of white dwarf (WD) binaries. Determining the brightness distribution is critical for evaluating whether such an explosion model could be responsible for a significant fraction of the observed population of SNe Ia. We argue that the brightness of an explosion realized via the violent merger model is determined by the mass of nickel 56 produced in the detonation of the primary WD. We use a set of sub-Chandrasekhar mass WD detonation models to derive a relationship between primary WD mass and expected peak bolometric brightness. We use this relationship to convert the masses of merging primary WDs from binary population models to a predicted distribution of explosion brightness and find a striking similarity between the shape of our theoretical peak-magnitude distribution and that observed for SNe Ia: our model produces a brightness distribution that roughly covers the range and matches the shape of the one observed for SNe Ia.

Full text available at http://de.arxiv.org/abs/1209.0645.