Duality in spatially resolved star-formation relations in local LIRGs
  We analyse the star formation (SF) relations in a sample of 16 nearby
luminous infrared galaxies (LIRGs) with more than 2800 regions defined on
scales of 90 to 500 pc. We used ALMA to map the distribution of the cold
molecular gas traced by the J = 2-1 line of CO and archival Pa\alpha HST/NICMOS
imaging to trace the recent SF. In four objects, we find two different branches
in the Kennicutt-Schmidt relation at 90 pc scales, suggesting the existence of
a duality in this relation. The two branches correspond to two different
dynamical environments within each galaxy. One branch, which corresponds to the
central region of these galaxies 90% of the regions are located at radii < 0.85
kpc), shows higher gas and star formation rate surface densities with higher
velocity dispersion. The other branch, which shows lower molecular gas and SF
rate surface densities, corresponds to the more external disk regions (r $\sim$
1 kpc). Despite the scatter, the SF efficiency of the galaxies with a dual
behaviour increases with increasing boundedness as measured by the b parameter
(b $\equiv$ $\Sigma_{H_{2}}$/$\sigma^{2}$ $\propto$ $\alpha_{vir}^{-1}$). At
larger spatial scales (250 and 500 pc), the duality disappears. The rest of the
sample does not show evidence of this dual behaviour at any scale.
