Precision of diffuse 21-cm lensing |
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| Authors: | Tingting Lu Ue-Li Pen |
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| Institution: | Department of Astronomy and Astrophysics, University of Toronto, Canada M5S 3H4;Canadian Institute for Theoretical Astrophysics, University of Toronto, Canada M5S 3H8 |
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| Abstract: | We study the limits of accuracy for weak lensing maps of dark matter using diffuse 21-cm radiation from the pre-reionization epoch using simulations. We improve on previous 'optimal' quadratic lensing estimators by using shear and convergence instead of deflection angles. This is a generalization of the deflection estimator, and is more optimal for non-Gaussian sources. The cross-power spectrum of shear and convergence is an unbiased estimator of lensing power spectrum which does not require knowledge of the source four-point function. We find that non-Gaussianity provides a limit to the accuracy of weak lensing reconstruction, even if instrumental noise is reduced to zero. The best reconstruction result is equivalent to Gaussian sources with effective independent cell of side length 2.0 h ?1 Mpc . Using a source full map from z = 10 to 20, this limiting sensitivity allows mapping of dark matter at a signal-to-noise ratio greater than 1 out to l ? 6000, which is better than any other proposed technique for large-area weak lensing mapping. |
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| Keywords: | gravitational lensing methods: N-body simulations cosmology: observations cosmology: theory dark matter large-scale structure of Universe |
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