Cosmological Backgrounds of Gravitational Waves and eLISA/NGO: Phase   Transitions, Cosmic Strings and Other Sources
  We review several cosmological backgrounds of gravitational waves accessible to direct-detection experiments, with a special emphasis on those backgrounds due to first-order phase transitions and networks of cosmic (super-)strings. For these two particular sources, we revisit in detail the computation of the gravitational wave background and improve the results of previous works in the literature. We apply our results to identify the scientific potential of the NGO/eLISA mission of ESA regarding the detectability of cosmological backgrounds. 
Pierre Bin\'etruy, Alejandro Boh\'e, Chiara Caprini, Jean-Fran\c{c}ois   Dufaux
gr-qc astro-ph.CO hep-ph hep-th