  Here we present the cloud population extracted from M51, following the
application of our new high-resolution dust extinction technique to the galaxy
(Faustino Vieira et al. 2023). With this technique, we are able to image the
gas content of the entire disc of M51 down to 5 pc (0.14"), which allows us to
perform a statistical characterisation of well-resolved molecular cloud
properties across different large-scale dynamical environments and with
galactocentric distance. We find that cloud growth is promoted in regions in
the galaxy where shear is minimised; i.e. clouds can grow into higher masses
(and surface densities) inside the spiral arms and molecular ring. We do not
detect any enhancement of high-mass star formation towards regions favourable
to cloud growth, indicating that massive and/or dense clouds are not the sole
ingredient for high-mass star formation. We find that in the spiral arms there
is a significant decline of cloud surface densities with increasing
galactocentric radius, whilst in the inter-arm regions they remain relatively
constant. We also find that the surface density distribution for spiral arm
clouds has two distinct behaviours in the inner and outer galaxy, with average
cloud surface densities at larger galactocentric radii becoming similar to
inter-arm clouds. We propose that the tidal interaction between M51 and its
companion (NGC 5195) - which heavily affects the nature of the spiral structure
- might be the main factor behind this.
