The degeneracy between primordial non-Gaussianity and foregrounds in 21cm intensity mapping experiments

Understand

Potential evidence for primordial non-Gaussianity (PNG) is expected to lie in the largest scales mapped by cosmological surveys.

• Forthcoming 21cm intensity mapping experiments will aim to probe these scales by surveying neutral hydrogen (HI) within galaxies.
• However, foreground signals dominate the faint 21cm emission, meaning foreground cleaning is required to recover the cosmological signal.
• The effect this has is to damp the HI power spectrum on the largest scales, especially along the line-of-sight.