Gravitational Waves ground based experiments, after a decade of detector installation and commissioning, have reached or surpassed their design sensitivities, opening a new window into the Universe. Not only one expects to discover a set of new exotic sources, but also to travel back in time, toward the very early stages of the evolution of the Universe.
The first generation of LIGO and Virgo interferometers has already put interesting astrophysical constraints on the ellipticity of known fast pulsars or the gravitational wave stochastic background. Second generation detectors such as Advanced LIGO/Virgo expected to start collecting data in 2014 with a sensitivity of about 10 times better, should make gravitational wave detections a routine occurrence, detecting a few tens of compact binary coalescences a year, while third generation detectors such as the planned Einstein Telescope (ET) (~2025), or the space antenna LISA, will bring GW astronomy to the next level, when it will be possible to detect a wide variety of sources, and address a large range of problems in astrophysics but also fundamental physics and cosmology. In particular, coalescing compact binaries that could be detected up to very large distances with advanced GW detectors and whose waveform is well modeled up to the last stable orbit are ideal standard candles (or standard sirens) that can be used to put constraints on the cosmological parameters and to shed light on the nature of dark energy (DE), one of the most compelling problem in physics.
In this talk, I''ll present the science potential of Einstein Telescope, and introduce the first results of the EInstein Telescope Mock Data Challenge.