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

Abstract

ABSTRACT 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 $4{{\ \rm per\ cent}}$ on w0, $1{{\ \rm per\ cent}}$ on h, $2{{\ \rm per\ cent}}$ on bH i using Band 1+Planck, and $3{{\ \rm per\ cent}}$ on w0, $0.5{{\ \rm per\ cent}}$ on h, $2{{\ \rm per\ cent}}$ on bH i 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 ≲ 1 and ℓ ≲ 100. Subject to the specific scan strategy of the adopted 1/f noise model, one prefers a correlation in frequency with minimized spectral slope, a low knee frequency, and a large telescope slew speed in order to reduce its impact.