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Ajinkya H. Patil et al., "Constraining the epoch of reionization
with the variance statistic: simulations of the LOFAR case,"
Monthly Notices of the Royal Astronomical Society, V443, no. 2,
pp1113-1124, September 2014.
abstract:
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 h of integration using the variance
statistic. Additionally, the redshift (zr) and duration
(Δz) of reionization can be constrained assuming a parametrization. We
use an EoR simulation of zr = 7.68 and Delta z = 0.43 to test
the pipeline. We are able to detect the simulated signal with a
significance of four standard deviations and extract the EoR
parameters as zr=7.72-0.18+0.37 and
Delta z=0.53-0.23+0.12 in 600 h, 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.
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