Observing the universe right after the cosmic microwave background

One of the most exciting radio science discoveries this year is the first detection of the epoch of reionization (EoR) signature. The measurement allows scientists to study the evolution of the early universe right after the big bang, by observing HI emission and absorption at 1.42 GHz. This signal is highly red-shifted, and was now observed at frequencies between 70 and 90 MHz. 

The study of the EoR signal has been the primary science goal for the large scale Low Frequency Array (LOFAR) and Square Kilometer Array (SKA) projects. However, one does not need a large >$100M project to make this observation. The team led by Judd Bowman and Alan Rogers showed that this can be performed with a single well calibrated broad band VHF dipole antenna, located in a radio quiet location.

The EoR signal is not only obscured by the galactic synchrotron emission, which overpowers it by a factor of 10000, but it is also affected by the Earth's ionosphere. The effects include dispersion, absorption, and emission. Some of these effects are discussed e.g., in this paper (shameless self-reference). The ionospheric signature is a calibration side product of the measurement. It needs to be estimated and removed from the spectrum, in order to see the EoR signal clearly.

After this initial EoR discovery, I am certain that there will be a flurry of activity to verify this observation. Many other initiatives similar to EDGES have already been attempting to make this observation, but these efforts have so far not been successful.

If the EoR signal is confirmed by others, there will be a very strong case for conducting future studies with space based low frequency telescopes, where man made interference, and deleterious ionospheric effects are not present. The most far reaching ideas I've seen, involve building a radio telescope the far side of the Moon! I would certainly hope to see this become reality during my lifetime. 

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