  Fast radio bursts (FRBs) with unknown origin emit a huge luminosity (about 1
Jy at 1 GHz) with a duration of milliseconds or less at extragalactic distances
estimated from their large dispersion measure (DM). We propose herein a
scenario for a collision between a neutron star (NS) and a white dwarf (WD) as
the progenitor of the FRBs by considering the burst duration scaling to the
collision time and the radio luminosity proportional to the kinetic energy of
the collision. The relations among the observed flux density, pulse width, and
the DM are derived from the model and compared with the statistical results
from the observed FRBs. Although the sample is quite small, we tentatively
report a nearly inverse-square correlation between the observed peak flux
density and the DM excess, which is an consequence of the assumption that the
DM excess (i.e. that not due to our Galaxy) is dominated by the intergalactic
medium. We also tentatively note a correlation among the duration of the FRB
and the DM excess (possibly interpreted as due to the broadening of the signal
in the intergalactic medium) and a correlation among the duration of the FRB
and the flux density (shorter burst should be brighter), both roughly in
agreement with the proposed model.
