A new joint analysis of data has found no conclusive evidence of primordial gravitational waves, despite earlier reports of a possible detection.
The data from two South Pole-based experiments, the BICEP2 telescope and the Keck Array, both supported by the National Science Foundation and the European Space Agency's Planck satellite, confirms the Planck observation: even following a more accurate analysis (and the adoption of new instruments) there is still evidence of contaminants that are difficult to control and preclude the possibility of making any definite statement on cosmological gravitational waves.
Carlo Baccigalupi, SISSA cosmologist explained that no investigation of this kind could escape a systematic study of contaminating sources and it could only be systematic if several instruments are used at the same time.
Planck can act as an "alarm bell," but owing to its very nature and the instrumental noise contained in its observations, it requires additional, "sharper" eyes to better distinguish the signal.
The study will be published in Physical Review Letters.