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Angular Power Spectrum with MWA

The Murchison Widefield Array (MWA) EoR experiment consists of the observation of ~1000 hours of data from two fields in the sky. These data are being processed to a spherical power spectrum, in order to attempt a detection of the weak signal from neutral hydrogen 0.5-1 billion years after the Big Bang. The spatial structure and evolution of the 21cm signal encodes a wealth of information about structure formation in the Universe, and helps us to understand which ionising sources are responsible for transitioning the Universe from the Dark Ages to the luminous cosmos observed today (first stars, bright or faint galaxies, black holes). The signal is extremely weak, and is embedded in noise and very bright contaminating foreground radio sources (galaxies, our Galaxy, free-free diffuse emission). Combined with a complicated instrument model, the EoR experiment is highly challenging.

The current MWA dataset suffers from missing frequency channels, which complicate the transformation to a spherical power spectrum. Also, the treatment of foreground sources is an ongoing research topic. By computing the angular power spectrum, where frequency information is treated separately, the foregrounds have a different signature, and the missing channels can be removed cleanly from the analysis. This project will use existing MWA EoR data to develop an optimal angular power spectrum algorithm and apply it to current data, in an attempt to provide the first detection of the EoR signal.