The Effect of Interplanetary Scintillation on Epoch of Reionisation Power Spectra

Abstract

Interplanetary Scintillation (IPS) induces intensity fluctuations in small angular size astronomical radio sources via the distortive effects of spatially and temporally varying electron density associated with outflows from the Sun. These radio sources are a potential foreground contaminant signal for redshifted HI emission from the Epoch of Reionisation (EoR) because they yield time-dependent flux density variations in bright extragalactic point sources. Contamination from foreground continuum sources complicates efforts to discriminate the cosmological signal from other sources in the sky. In IPS, at large angles from the Sun applicable to EoR observations, weak scattering induces spatially and temporally correlated fluctuations in the measured flux density of sources in the field, potentially affecting the detectability of the EoR signal by inducing non-static variations in the signal strength. In this work, we explore the impact of interplanetary weak scintillation on EoR power spectrum measurements, accounting for the instrumental spatial and temporal sampling. We use published power spectra of electron density fluctuations and parameters of EoR experiments to derive the IPS power spectrum in the wavenumber phase space of EoR power spectrum measurements. The contrast of IPS power to expected cosmological power is used as a metric to assess the impact of IPS. We show that IPS has a different spectral structure to power from foregrounds alone, but the additional leakage into the EoR observation parameter space is negligible under typical IPS conditions, unless data are used from deep within the foreground contamination region.

Accepted to the Astrophysical Journal; 21 pages, 6 figures

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Cited by in corpus (5)

• First Limits on the 21 cm Power Spectrum during the Epoch of X-ray heating
• Spectral calibration requirements of radio interferometers for Epoch of Reionisation science with the SKA
• Contribution of Radio Halos to the Foreground for SKA EoR Experiments
• Contribution of Galactic free-free emission to the foreground for EoR signal in SKA experiments
• A Monte Carlo Implementation of Galactic Free-Free Emission for the EoR Foreground Models