Extracting the Signal of Cosmic String Wakes from 21-cm Observations
  A cosmic string wake produces a distinct non-Gaussian signal in 21-cm
intensity maps at redshifts above that of reionization. While the string signal
is (locally) larger in amplitude than the signal of the Gaussian fluctuations
of the $\Lambda$CDM model, they are overwhelmed (even locally in position
space) by astrophysical and instrumental foregrounds. Here, we study to what
extent the signal can be extracted from noisy interferometric data. The
narrowness of the string-induced feature in redshift direction allows for a
subtraction of astrophysical and instrumental foregrounds. Based on the
specific geometry of the string signal we identify a particular three-point
statistic which is promising in order to extract the signal, and we find that,
having in mind a telescope of specifications similar to that of the MWA
instrument, the string signal can be successfully extracted for a value of the
string tension of $G\mu = 3 \times 10^{-7}$. Prospects for further improvements
of the analysis are discussed.
