Speaker
Description
Galaxy surveys can be photometric (big volumes but also big redshift errors) or spectroscopic (accurate redshifts but small volumes). The technique that goes beyond this compromise is hydrogen intensity mapping (HI IM). Indeed, radio telescopes tomographically characterise the Universe, detecting the redshifted 21 cm radiation emitted by cosmic neutral hydrogen: both large areas and spectroscopic information are ensured. In this talk, I will present the HI IM technique and discuss its challenges and opportunities. In particular, I will show how we address the (in)famous contaminant separation problem with first-of-their-kind data from the MeerKAT telescope single-dish observations. Within the MeerKLASS collaboration, we started an effort to test and optimise the available contaminant cleaning methods directly on data. We assess their effectiveness by measuring the expected cross-correlation signal with an overlapping galaxy dataset. I'll present our results, which are encouraging and relevant for the forthcoming direct detection of the IM signal with MeerKAT. Our ongoing work demonstrates that a radio array operating as a collection of independent telescopes can probe the IM cosmological signal, marking a milestone for the cosmology science case with the entire SKA Observatory (which the MeerKAT dishes will be part of).
