Several experiments are underway to detect the cosmic redshifted 21-cm signal from neutral hydrogen from the Epoch of Reionization ( EoR ) .
Due to their very low signal-to-noise ratio , these observations aim for a statistical detection of the signal by measuring its power spectrum .
We investigate the extraction of the variance of the signal as a first step towards detecting and constraining the global history of the EoR .
Signal variance is the integral of the signal ’ s power spectrum , and it is expected to be measured with a high significance .
We demonstrate this through results from a simulation and parameter estimation pipeline developed for the Low Frequency Array ( LOFAR ) -EoR experiment .
We show that LOFAR should be able to detect the EoR in 600 hours of integration using the variance statistic .
Additionally , the redshift ( z _ { r } ) and duration ( \Delta z ) of reionization can be constrained assuming a parametrization .
We use an EoR simulation of z _ { r } = 7.68 and \Delta z = 0.43 to test the pipeline .
We are able to detect the simulated signal with a significance of 4 standard deviations and extract the EoR parameters as z _ { r } = 7.72 ^ { +0.37 } _ { -0.18 } and \Delta z = 0.53 ^ { +0.12 } _ { -0.23 } in 600 hours , assuming that systematic errors can be adequately controlled .
We further show that the significance of detection and constraints on EoR parameters can be improved by measuring the cross-variance of the signal by cross-correlating consecutive redshift bins .