Carucci, Isabella Paola
Italy – INAF – Trieste
Hydrogen Intensity Mapping: The ultimate signal is the weakest of all
Probing the Universe’s cold gas content and large-scale structure (LSS) leads to a wealth of astrophysical and cosmological information. With the advent of unprecedentedly giant radio telescopes, we can start using the neutral hydrogen (HI) 21-cm emission to trace the LSS. In particular, a novel observational strategy is catching on: Intensity Mapping (IM). With IM, we relax the requirement of source detection and go after all the integrated 21-cm emissions: we can produce detailed three-dimensional maps of a good fraction of the observable Universe, probing at the same time the distribution and cosmic amount of HI, the principal fuel of stars, at redshifts usually inaccessible by standard surveys. On the one hand, this strategy carries a potentially revolutionary science output. But, on the other, these observations have been extremely challenging to perform. In particular, disentangling the HI IM signal from orders-of-magnitude more intense and intricate contaminants is the thorniest problem. In this talk, I will discuss how we address this challenge with first-of-their-kind observational data from the MeerKAT radio telescope, a precursor to the SKA Observatory (SKAO). Our ongoing work demonstrates that a radio array operating as a collection of independent telescopes can probe the IM signal, marking a milestone for the science case with the entire SKAO.