Impact of $1/f$ noise on cosmological parameter constraints for SKA intensity mapping

We investigate the impact of 1 /f noise on cosmology for an intensity mapping survey with SKA1-MID Band 1 and Band 2. We use a Fisher matrix approach to forecast constraints on cosmological parameters under the influence of 1 /f noise, adopting a semi-empirical model from an earlier work, which results from the residual 1 /f noise spectrum after applying a component separation algorithm to remove smooth spectral components. Without 1 /f noise, the projected constraints are 4% on w 0 , 1% on h , 2% on b HI using Band 1+ Planck , and 3% on w 0 , 0 . 5% on h , 2% on b HI using Band 2+ Planck . A representative baseline 1 /f noise degrades these constraints by a factor of ∼ 1 . 5 for Band 1+ Planck , and ∼ 1 . 2 for Band 2+ Planck . On the power spectrum measurement, higher redshift and smaller scales are more affected by 1 /f noise, with minimal contamination comes from z (cid:46) 1 and (cid:96) (cid:46) 100. Subject to the specific scan strategy of the adopted 1 /f noise model, one prefers a correlated in frequency with minimised spectral slope, a low knee frequency, and a large telescope slew speed in order to reduce its impact.