Max Tegmark's cosmology library: lensing
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Is lensing of point sources a problem for future CMB experiments?
Max Tegmark &
No. Weak gravitational lensing from large-scale structure
enhances and reduces the fluxes from extragalactic
point sources with an rms amplitude of order 15%.
In cosmic microwave background (CMB) experiments, all
sources exceeding some flux threshold are removed,
which means that lensing will modulate the brightness map
of the remaining unresolved sources. Since this mean
brightness is of order 100 micro-Kelvin at 30 GHz for a
reasonable flux cut, one might be concerned that this modulation
could cause substantial problems for future CMB experiments.
We present a detailed calculation of this effect
and, fortunately, find that its power spectrum is
always smaller than the normal point source power spectrum.
Thus although this effect should be taken into account in a
detailed CMB analysis, it will not substantially reduce the
accuracy with which cosmological parameters can be measured.
MNRAS, 289, 169-174 (1997)
This site also contains the latest versions of some papers that are referenced in
Tegmark & Efstathiou 1996 ("TE96"),
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This page was last modified July 1, 1998.