Abstract: Sub-Chandrasekhar mass carbon-oxygen white dwarfs (CO WDs) with a surfacehelium (He) shell have been proposed as progenitors of Type Ia supernovae (SNeIa). If true, the resulting thermonuclear explosions should be able to accountfor at least some of the range of SNe Ia observables. To study this, we conducta parameter study based on 3D simulations of double detonations in CO WDs witha He shell, assuming different core and shell masses. An admixture of C to theshell and solar metallicity are included in the models. The hydrodynamicsimulations are carried out using the AREPO code. This allows us to follow theHe shell detonation with high numerical resolution, and improves thereliability of predicted nucleosynthetic shell detonation yields. The additionof C to the shell leads to a lower production of 56Ni while including solarmetallicity increases the production of IMEs. The production of higher masselements is further shifted to stable isotopes at solar metallicity. Moreover,we find different core detonation ignition mechanisms depending on the core andshell mass configuration. This has an influence on the ejecta structure. Wepresent the bolometric light curves predicted from our explosion simulationsusing the radiative transfer code ARTIS, and make comparisons with SNe Ia data.The bolometric light curves of our models show a range of brightnesses, able toaccount for sub-luminous to normal SNe Ia. We show the model bolometricwidth-luminosity relation compared to data for a range of viewing angles. Wefind that, on average, our brighter models lie within the observed data. Theejecta asymmetries produce a wide distribution of observables, which mightaccount for outliers in the data. However, the models overestimate the extentof this compared to data. We also find the bolometric decline rate over 40 daysappears systematically faster than data. (abridged)

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