Seminari
Monday 16/11/2020 @ 14:00, On-line - meet.google.com/sue-bwvk-axf
Marta Spinelli (INAF OATS), "Measurements of the global 21 cm signal at z > 6: current status"
The challenging measurement of a signal from the Cosmic Dawn of the Universe finds its most promising observable in the 21cm line of the neutral Hydrogen, whose sky averaged (global) 21cm signal can in principle be measured with single dipole antennas. The Experiment to Detect the Global Epoch-of-Reionization Signatures (EDGES) team has claimed detection of a broad absorption profile peaking at -520mK and centered at 78 MHz. This is more than a factor two deeper than predicted from theory based on standard physics. Subsequent analysis by other authors have suggested the existence of a residual unmodeled systematics in EDGES data that could modify their best fit parameters. In the first part of this talk, we discuss the EDGES result and some of its criticisms. The importance and the implications of the EDGES result need confirmation from another independent experiment to be fully convincing. In the second part of the talk, we review the current observational status of the global signal, particularly focusing on the Large aperture Experiment to detect the Dark Ages (LEDA). We discuss our latest season of data-taking and its contribution to the study of the low-frequency radio sky.