Characterizing and Mitigating Radio Frequency Interference in Reionization Cosmology

Wed 9th Oct 2019 @2:15 PM, level 7, David Caro Building

Mike Wilensky



Through radio interferometry, we use redshifted 21cm radiation from neutral Hydrogen as a probe into the universe’s ionization history. The relevant wavelengths for observation are concurrent with those allocated for common radio broadcasts such as FM radio and digital television. Consequently, these transmissions can interfere with radio observations, and are thus dubbed radio frequency interference (RFI). The ever-looming threat of radio frequency interference demands that radio telescopes be placed in extremely remote locations. Even still, extremely remote telescopes such as the Murchison Widefield Array observe interference at non-negligible levels. In this talk, we introduce a new RFI mitigation strategy, known as Sky-Subtracted Incoherent Noise Spectra (SSINS), which was designed to detect extremely faint RFI. We show that the increased RFI mitigation afforded by SSINS makes a noticeable difference in redshifted 21cm power spectrum estimations. Furthermore, through analytic calculations and simulations, we characterize the expected effect of RFI on 21cm power spectra. Ultimately we conclude that RFI poses a serious threat to reionization science, and that pristine site conditions will be essential to making a detection of Hydrogen reionization.