Merger rate of double carbon/oxygen white dwarfs with a total mass above the Chandrasekhar mass as a function of delay time. Rates are in yr^-1 per 10¹⁰ M_⊙ formed stellar mass of the parent galaxy. Solar metallicity (Z = 0.02) is assumed. Delay times are shown for two different prescriptions of the CE phase. In black we plot model γα and in grey model αα, see Sect. 3. Overplotted with black circles are the observed values of the SNIa rate of Totani et al. (2008), Maoz et al. (2010), Maoz & Badenes (2010) and Maoz et al. (2011; for a review Maoz & Mannucci 2012). For comparison the grey circles show the observations scaled down by a factor 10.