The impact of the halo spin-concentration relation on disc scaling laws
  Galaxy scaling laws, such as the Tully-Fisher, mass-size and Fall relations,
can provide extremely useful clues on our understanding of galaxy formation in
a cosmological context. Some of these relations are extremely tight and well
described by one single parameter (mass), despite the theoretical existence of
secondary parameters such as spin and concentration, which are believed to
impact these relations. In fact, the residuals of these scaling laws appear to
be almost uncorrelated with each other, posing significant constraints on
models where secondary parameters play an important role. Here, we show that a
possible solution is that such secondary parameters are correlated amongst
themselves, in a way that removes correlations in observable space. In
particular, we focus on how the existence of an anti-correlation between the
dark matter halo spin and its concentration -- which is still debated in
simulations -- can weaken the correlation of the residuals of the Tully-Fisher
and mass-size relations. Interestingly, using simple analytic galaxy formation
models, we find that this happens only for a relatively small portion of the
parameter space that we explored, which suggests that this idea could be used
to derive constraints to galaxy formation models that are still unexplored.
