  High performance computing numerical simulations are today one of the more
effective instruments to implement and study new theoretical models, and they
are mandatory during the preparatory phase and operational phase of any
scientific experiment. New challenges in Cosmology and Astrophysics will
require a large number of new extremely computationally intensive simulations
to investigate physical processes at different scales. Moreover, the size and
complexity of the new generation of observational facilities also implies a new
generation of high performance data reduction and analysis tools pushing toward
the use of Exascale computing capabilities. Exascale supercomputers cannot be
produced today. We discuss the major technological challenges in the design,
development and use of such computing capabilities and we will report on the
progresses that has been made in the last years in Europe, in particular in the
framework of the ExaNeSt European funded project. We also discuss the impact of
this new computing resources on the numerical codes in Astronomy and
Astrophysics.
