Toward Epoch of Re-ionization Measurements with Wide-Field LOFAR Observations

This paper explores the potential for statistical epoch of re-ionization (EOR) measurements using wide field LOFAR observations. New developments in low frequency radio instrumentation and wide field signal processing allow very sensitive EOR measurements, and the analysis techniques enabled by these advances offer natural ways of separating the EOR signal from the residual foreground emission. This paper introduces the enabling technologies and proposes an analysis technique designed to make optimal use of the capabilities of LOFAR. In the absence of foreground contamination, the measurements we propose are more sensitive than others that have been discussed in the literature, with five 3-sigma power spectrum points in only 100 hours of observation with 4 MHz bandwidth for simple models of the high redshift 21 cm emissions. The challenge of residual foreground removal may be addressed by the symmetries inherent in the three-dimensional (two spatial frequencies and radiofrequency) nature of the radio interferometric data.