Athena+: The first Deep Universe X-ray Observatory
  The Advanced Telescope for High-energy Astrophysics (Athena+) is being
proposed to ESA as the L2 mission (for a launch in 2028) and is specifically
designed to answer two of the most pressing questions for astrophysics in the
forthcoming decade: How did ordinary matter assemble into the large scale
structures we see today? and how do black holes grow and shape the Universe?
For addressing these two issues, Athena+ will provide transformational
capabilities in terms of angular resolution, effective area, spectral
resolution, grasp, that will make it the most powerful X-ray observatory ever
flown. Such an observatory, when opened to the astronomical community, will be
used for virtually all classes of astrophysical objects, from high-z gamma-ray
bursts to the closest planets in our solar neighborhood. In this paper, we
briefly review the core science objectives of Athena+, present the science
requirements and the foreseen implementation of the mission, and illustrate its
transformational capabilities compared to existing facilities.
