Supernovae and their host galaxies -- VII. The diversity of Type Ia
  supernova progenitors
  We present an analysis of the light curve (LC) decline rates $(\Delta
m_{15})$ of 407 normal and peculiar supernovae (SNe) Ia and global parameters
of their host galaxies. As previously known, there is a significant correlation
between the $\Delta m_{15}$ of normal SNe Ia and global ages (morphologies,
colours, masses) of their hosts. On average, those normal SNe Ia that are in
galaxies from the Red Sequence (early-type, massive, old hosts) have faster
declining LCs in comparison with those from the Blue Cloud (late-type, less
massive, younger hosts) of the colour-mass diagram. The observed correlations
between the $\Delta m_{15}$ of normal SNe Ia and hosts' parameters appear to be
due to the superposition of at least two distinct populations of faster and
slower declining normal SNe Ia from older and younger stellar components. We
show, for the first time, that the $\Delta m_{15}$ of 91bg- and 91T-like SNe is
independent of host morphology and colour. The distribution of hosts on the
colour-mass diagram confirms the known tendency for 91bg-like SNe to occur in
globally red/old galaxies while 91T-like events prefer blue/younger hosts. On
average, the youngest global ages of 02cx-like SNe hosts and their positions in
the colour-mass diagram hint that these events likely originate from young
population, but they differ from 91T-like events in the LC decline rate.
Finally, we discuss the possible explosion channels and present our favoured SN
Ia models that have the potential to explain the observed SN-host relations.
