Internal dark matter structure of the most massive galaxy clusters since
  redshift 1
  We investigate the evolution of the dark matter density profiles of the most
massive galaxy clusters in the Universe. Using a `zoom-in' procedure on a large
suite of cosmological simulations of total comoving volume of $3\,(h^{-1}\,\rm
Gpc)^3$, we study the 25 most massive clusters in four redshift slices from
$z\sim 1$ to the present. The minimum mass is $M_{500} > 5.5 \times 10^{14}$
M$_{\odot}$ at $z=1$. Each system has more than two million particles within
$r_{500}$. Once scaled to the critical density at each redshift, the dark
matter profiles within $r_{500}$ are strikingly similar from $z\sim1$ to the
present day, exhibiting a low dispersion of 0.15 dex, and showing little
evolution with redshift in the radial logarithmic slope and scatter. They have
the running power law shape typical of the NFW-type profiles, and their inner
structure, resolved to $3.8\,h^{-1}$ comoving kpc at $z=1$, shows no signs of
converging to an asymptotic slope. Our results suggest that this type of
profile is already in place at $z>1$ in the highest-mass haloes in the
Universe, and that it remains exceptionally robust to merging activity.
