Speaker
Description
Direct observation of the Cosmic Dawn and Epoch of Reionization via the redshifted 21-cm line will have unprecedented implications on the study of structure formation in the early Universe. This exciting goal is challenged by the difficulty of extracting the feeble 21-cm signal buried under bright astrophysical foregrounds and contaminated by numerous systematics. The LOFAR-EoR and NenuFAR Cosmic Dawn projects aim to statistically detect the 21-cm signal fluctuations from the EoR and Cosmic Dawn, and to pave the way for the SKA EoR/CD experiment, which will be capable of directly imaging the large-scale neutral hydrogen structures from these distant epochs.
In this talk, I will present the latest results from the LOFAR-EoR and NenuFAR Cosmic Dawn collaborations. The LOFAR-EoR team recently published a new and deeper upper limit on the 21-cm signal power spectrum, now extending across a broader redshift range, further tightening constraints on the thermal and ionisation history of the intergalactic medium during the EoR. On the Cosmic Dawn front, the NenuFAR team is preparing the release of a new upper limit around z∼20, which for the first time allows constraints on non-standard models predicting an excess in the diffuse radio background.
These new results will be discussed, along with the advances in calibration and foreground mitigation that enabled them. I will also address their broader implications for the upcoming SKA-Low CD/EoR observations.
