Exploring the Cosmic Dawn with NenuFAR
  The exploration of the Cosmic Dawn, the period of the Universe during which
the first stars and galaxies were formed, is one of the last frontiers of
modern astronomy and cosmology. The redshifted 21-cm line emission from neutral
hydrogen is a unique probe and can open this era for astrophysical and
cosmological studies. The tentative detection of the 21-cm global signal by the
EDGES team at $z \sim 17$ underlines the need for an interferometric detection
of this signal to discriminate between the numerous models trying to explain
this unexpected discovery. The NenuFAR Cosmic-Dawn Key-Science Program aims to
perform this detection in the redshift range $z \sim 15 - 31$ with a novel SKA
precursor, the NenuFAR radio telescope located at the Station de
Radioastronomie de Nan\c{c}ay and that started operating in 2019. Due to its
compactness it is particularly sensitive to the large scale of the 21-cm
signal. Only 100 hours of observation are needed to reach the level of the most
extreme models, while 1000 hours are needed for the more standard models.
Observations have already started, accumulating to almost 500 hours on the
North Celestial Pole field. In this contribution, we introduce the project, our
first results and the developments in calibration and RFI mitigation specific
to this new instrument.
