  Broad-lined type Ic supernovae (SNe Ic-BL) are a subclass of rare core
collapse SNe whose energy source is debated in the literature. Recently a
series of investigations on SNe Ic-BL with the magnetar (plus 56Ni) model were
carried out. Evidence for magnetar formation was found for the well-observed
SNe Ic-BL 1998bw and 2002ap. In this paper we systematically study a large
sample of SNe Ic-BL not associated with gamma-ray bursts. We use photospheric
velocity data determined in a homogeneous way. We find that the magnetar+56Ni
model provides a good description of the light curves and velocity evolution of
our sample of SNe Ic-BL, although some SNe (not all) can also be described by
the pure-magnetar model or by the two-component pure-56Ni model (3 out of 12
are unlikely explained by two-component model). In the magnetar+56Ni model, the
amount of 56Ni required to explain their luminosity is significantly reduced,
and the derived initial explosion energy is, in general, in accordance with
neutrino heating. Some correlations between different physical parameters are
evaluated and their implications regarding magnetic field amplification and the
total energy reservoir are discussed.
