Detecting the sky-averaged 21-cm line from atomic Hydrogen




Eloy de Lera Acedo


Dongwon Han


31-01-2022 at 1:00 pm - 2:00 pm



In this talk I will present our current efforts to detect the elusive 21-cm line from atomic Hydrogen. With the promise of opening a new window to studies of the early Universe: Dark Ages, Cosmic Dawn, Epoch of Reionization, the so-called 21-cm signal (originating at 21-cm wavelength and redshifted to a few m) is still to be detected. Here in Cambridge we lead the Radio Experiment for the Analysis of Cosmic Hydrogen (REACH), a sky-averaged radiometer experiment aiming at a confident detection of the 21-cm line by tackling some of the main challenges faced bye today’s instruments. These are the calibration of the foregrounds (5 orders of magnitude brighter than the expected cosmological signal) and the calibration of instrumental effects (the cause of much of the bottlenecks found by current telescopes). I will discuss how REACH aims at either confirming or disproving the observations published by EDGES in 2018 and to improve on the current best upper limits from the SARAS monopole experiment. At the end of the talk I will discuss our plans to move to space in the future, to the quietest observation location in the Solar system: in orbit at the far-side of the Moon, and why that could be a game changer for this type of experiments.