Evidence for the Fifth Element Astrophysical status of Dark Energy

Understand

Evidence for an accelerated expansion of the universe as it has been revealed ten years ago by the Hubble diagram of distant type Ia supernovae represents one of the major modern revolutions for fundamental physics and cosmology.

• It is yet unclear whether the explanation of the fact that gravity becomes repulsive on large scales should be found within general relativity or within a new theory of gravitation.
• However, existing evidences for this acceleration all come from astrophysical observations.
• Before accepting a drastic revision of fundamental physics, it is interesting to critically examine the present situation of the astrophysical observations and the possible limitation in their interpretation.