LUNAR webinar, 30th Oct. 2012

Ravi Subrahmanyan (NRAO/RRI)

Steps to the reionization epoch



Precision measurements of the cosmic radio background are key to issues concerning the cosmic evolution of gas and galaxies across Hubble time. Perhaps most widely known is the highly redshifted 21-cm spatial and spectral signature, which is predicted to arise from events at the cosmic dawn that are associated with the formation of first stars and galaxies and their impact on the gas. There are many ongoing experimental efforts that attempt to detect the cosmological evolution in gas via its spectral distortions in the cosmic microwave background radiation; there are also Fourier synthesis telescopes being purpose built for detecting the spatial and velocity space fluctuations in redshifted 21-cm from the epoch of re-ionization. The signatures are trace features that are a tiny fraction of the cosmic radio background and designing purpose-built radio telescopes for their detection presents a formidable challenge. I will describe progress in the development of some systems for detecting the epoch of reionization SARAS: a shaped antenna experiment, ZEBRA: a zero-spacing interferometer, and MWA: the Murchison Widefield Array.