## Weak lensing correlation function errors

Charles Shapiro
Posts: 24
Joined: February 05 2005
Affiliation: University of Portsmouth

### Weak lensing correlation function errors

Hi All,

Most papers will tell you that the uncertainty in the weak lensing power spectrum is (e.g. Hu and Tegmark 1998)
$\Delta P_{\psi}=\sqrt{\frac{2}{(2l+1)f_{\rm sky}}}(P_{\psi}+\frac{4}{n}<\gamma^2_{\rm int}>)$

...but can someone please point me to a derivation of the analogous formula for the correlation function?

Chaz

Sarah Bridle
Posts: 144
Joined: September 24 2004
Affiliation: University College London (UCL)
Contact:

### Weak lensing correlation function errors

I had the impression that there is no similarly simple formula for the correlation function.
There is some discussion of errors on the correlation function in Simon, King & Schneider astro-ph/0309032, in case that helps.

Charles Shapiro
Posts: 24
Joined: February 05 2005
Affiliation: University of Portsmouth

### Weak lensing correlation function errors

That's unfortunate! From what I've managed to scribble down, I guess I'm not surprised. Thanks for the tip.

Chaz

Patrick Simon
Posts: 1
Joined: August 14 2006
Affiliation: Argelander-Institut fuer Astronomie, Bonn
Contact:

### Weak lensing correlation function errors

Hi everyone,

you should also have a look at Schneider et al. (2002), astro-ph/0206182,
where an estimate of the covariance for two-point shear-shear correlations in the Gaussian limit is given.

But, sadly, sadly, sadly, it is not a nice and handy small formula, as Sarah has already mentioned. The problem is that statistical errors become correlated for different scales, if you work with real-space correlation functions, while power spectra (of Gaussian random fields without gaps, at least?) have uncorrelated errors for different modes.

Patrick

Charles Shapiro
Posts: 24
Joined: February 05 2005
Affiliation: University of Portsmouth

### Weak lensing correlation function errors

The Schneider et al. paper is useful - thank you.

Chaz