  The results of a search for new heavy $W^\prime$ bosons decaying to an
electron or muon and a neutrino using proton-proton collision data at a
centre-of-mass energy of $\sqrt{s} = 13$ TeV are presented. The dataset was
collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider
and corresponds to an integrated luminosity of 36.1 fb$^{-1}$. As no excess of
events above the Standard Model prediction is observed, the results are used to
set upper limits on the $W^\prime$ boson cross-section times branching ratio to
an electron or muon and a neutrino as a function of the $W^\prime$ mass.
Assuming a $W^\prime$ boson with the same couplings as the Standard Model $W$
boson, $W^\prime$ masses below 5.1 TeV are excluded at the 95% confidence
level.
