A new analysis of data from the Planck satellite gives constraints on the state of the Universe in the very first moments after its creation. There is no indication in sky observations of any particular patterns indicative of the existence of primordial gravitational waves, the ripples of space-time generated during cosmic inflation.
The analysis was carried out by a team led by M. Tristram (CMB Team, A2C Pole) and which includes other scientists from France, as well as the United States, Canada, Norway and Spain. Their result, based on data from the Planck satellite, shows that gravitational waves cannot contribute more than 6% of the detected CMB signals. When combined with data from the BICEP experiment, the joint limit is reduced to 4%. This puts a direct limit on the energy scale of physics that may have generated cosmic inflation. Further research is underway to try to detect this bias signal at even lower levels. These new results underscore just how demanding the task facing scientists is.