CAMB_sources: number counts spectra including lensing effect

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Jun-Qing Xia
Posts: 22
Joined: January 02 2005
Affiliation: SISSA, Italy

CAMB_sources: number counts spectra including lensing effect

Post by Jun-Qing Xia » June 10 2009

Hi Antony,

I have a question about the number counts spectra including lensing effect. In the param.ini, there is a option:

#Whether number counts spectra include lensing effect
DoRedshiftLensing = F

Is there any document about this?

Meanwhile, I find some other papers which discuss the magnification of number counts from gravitational lensing effect, such as Eq.21 of Ho et al. PRD78,043519(2008) and Scranton et al. ApJ633:589(2005). But in these papers when they consider the lensing effect, the slope of number counts of the galaxy density as a function of flux \alpha [N(>F)~F^{-\alpha}] is needed.

But I don't find anything about this slope in the CAMB_sources code. So I wonder whether the method of including lensing effect in CAMB_sources is equivalent with ones in these two papers above. If not, is there any reference about the method in the code?

Thanks!

Junqing

Antony Lewis
Posts: 1498
Joined: September 23 2004
Affiliation: University of Sussex
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Re: CAMB_sources: number counts spectra including lensing ef

Post by Antony Lewis » June 10 2009

The current version of CAMB_sources does not include magnification bias from the source flux slope. The magnification that can be included via the lensing parameter is assuming you detect all sources regardless of magnification.

I think it is a fairly simple modification to adjust the magnification term if you want to include the magnification bias effect.

[we are sitting on a paper about some of the sources code, but have been for quite a long time now, so it may not be out soon...]

Jun-Qing Xia
Posts: 22
Joined: January 02 2005
Affiliation: SISSA, Italy

CAMB_sources: number counts spectra including lensing effect

Post by Jun-Qing Xia » June 10 2009

Thanks! It seems I have to modify the window function subroutine to include the magnification bias effect.

Junqing

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