  SN2010ah, a very broad-lined type Ic 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 GRB/SNe,
suggesting a high explosion kinetic energy. However, no GRB was detected in
association with the SN. Here, the properties of SN2010ah 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 SN1998bw. 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 SN2010ah, 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 SN2010ah are:
ejected mass ~ 3 Mo; kinetic energy ~10^52 erg, M(56Ni) ~ 0.25 Mo. The mass
located at v >~ 0.1c is ~0.2 Mo. Although these values, in particular the
kinetic energy, are quite large for a SN Ic, they are all smaller (especially
the ejecta mass) 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 SN2010ah may not meet although it comes quite close.
Depending on whether a neutron star or a black hole was formed following core
collapse, SN2010ah was the explosion of a CO core of ~ 5-6 Mo, pointing to a
progenitor mass of ~24 - 28 Mo.
