Description
Intensity mapping is a technique which maps the unresolved flux of redshifted line emission in 3D. 21cm emission from neutral hydrogen (HI) is particularly useful as most HI in the post-reionisation Universe acts as a tracer of large-scale structure. These scales can provide insights into the most important questions in cosmology, such as constraining the nature of dark energy using BAO detections, which intensity mapping is particularly well suited to observe, through its ability to map out large volumes of the sky quickly. As an SKA precursor, the MeerKAT telescope is already being used for intensity mapping as part of the MeerKLASS survey. The full SKA-mid AA* promises to bring access to intensity mapping at higher redshifts than previously detectable. However, hindering current intensity mapping science is the lack of knowledge about the full primary beam. The beam profile injects structure into the foregrounds, which are 3 – 5 orders of magnitude larger than the HI signal, destroying their smoothness across frequency and making their removal more difficult. One key aspect of the beam that has yet to be fully addressed is the oscillating beam size across frequency and its angular asymmetry. Accurately modelling the full primary beam will allow for the complete correction of any structure contaminating the foreground, ensuring its full removal. This will be an important step towards progressing the field of intensity mapping into precision cosmology. In this work I present simulation-based results that demonstrate the complications this can cause for intensity mapping clustering statistics.
