Milli-Hertz Gravitational Waves: LISA and PathFinder

Alberto Lobo

Ground based GW detectors are limited at their lower frequency band (1-10 Hz) by settlement gravity and seismic noise, while their sensitivity peaks at around 100 Hz. Sources in this band are mostly short duration signals, and their rates uncertain. Going down to milli-Hertz frequencies increases the number of sources, their intensities and their rates, which is why LISA has been planned. In this talk I will present the main concepts on which GW detection with LISA is based, and briefly report on its development status. In particular, emphasis will be placed on LISA PAthFinder, the ESA technology precursor of LISA, in which a Barcelona research group is heavily involved. I will also discuss the PathFinder concept as well as its implications for LISA.