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,
pp11131124, September 2014.
abstract:
Several experiments are underway to detect the cosmicredshifted 21cm
signal from neutral hydrogen from the Epoch of Reionization (EoR). Due
to their very low signaltonoise 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 LowFrequency
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 (z_{r}) and duration
(Δz) 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 four standard deviations and extract the EoR
parameters as z_{r}=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 crossvariance of the signal by
crosscorrelating consecutive redshift bins.
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