2013MNRAS.432.2463M

SN 2010ah, a very broad-lined Type Ic supernova (SN) discovered by the Palomar Transient Factory, was interesting because of its relatively high luminosity and the high velocity of the absorption lines, which was comparable to that of gamma-ray burst (GRB)/SNe, suggesting a high explosion kinetic energy. However, no GRB was detected in association with the SN. Here, the properties of SN 2010ah are determined with higher accuracy than previous studies through modelling. New Subaru telescope photometry is presented. A bolometric light curve is constructed taking advantage of the spectral similarity with SN 1998bw. Radiation transport tools are used to reproduce the spectra and the light curve. The results thus obtained regarding ejecta mass, composition and kinetic energy are then used to compute a synthetic light curve. This is in reasonable agreement with the early bolometric light curve of SN 2010ah, but a high abundance of 56Ni at high velocity is required to reproduce the early rise, while a dense inner core must be used to reproduce the slow decline at late phases. The high-velocity 56Ni cannot have been located on our line of sight, which may be indirect evidence for an off-axis, aspherical explosion. The main properties of SN 2010ah are: ejected mass Mej ~ 3M☉; kinetic energy Ekin ~ 1052 erg, M(56Ni) ~ 0.25M☉. The mass located at v ≳ 0.1 c is ∼ 0.2M☉. Although these values, in particular the Ekin, are quite large for a Type Ic SN, they are all smaller (especially Mej) than those typical of GRB/SNe. This confirms the tendency for these quantities to correlate, and suggests that there are minimum requirements for a GRB/SN, which SN 2010ah may not meet although it comes quite close. Depending on whether a neutron star or a black hole was formed following core collapse, SN 2010ah was the explosion of a CO core of ∼ 5 to 6M☉, pointing to a progenitor mass of ∼ 24-28M☉.