The NenuFAR Cosmic Dawn project has recently made progress in exploring the Cosmic Dawn using the 21cm transition line from neutral hydrogen. A recent study [1], analyzing one night of observation of the North Celestial Pole deep field with the NenuFAR radio telescope, provided new limits on the fluctuations of the transition line at 21 cm from neutral hydrogen. These observations will help to study the conditions of formation of the first stars, approximately 180 million years after the Big Bang, a key epoch in the evolution of the universe.
NenuFAR, a low-frequency radio interferometer located at the Nançay Radioastronomy Observatory in France, is distinguished by its large collecting surface, making it exceptionally sensitive for observing the 21 cm signal from the Cosmic Dawn. Observing this signal is complex due to signal interferences from our galaxy and other celestial sources, which overshadow the weak signal from the Cosmic Dawn. The team implemented advanced techniques to try to isolate this signal.
These advances mark significant progress towards understanding the Cosmic Dawn. However, this is only a first step and many challenges remain to directly observe this signal. The team continues to improve its analysis and observation methods, with the ultimate goal of directly observing the Cosmic Dawn.
[1] First upper limits on the 21-cm signal power spectrum from the Cosmic Dawn from one night of observations with NenuFAR. Munshi, S., Mertens, F., Koopmans, L.V.E. et al. 2023. A&A