CosmoCoffee

Sudeep Das · Posted: December 12 2006

Does the Lensing potential power spectrum $C_l^{\phi}$ that CAMB churns out include nonlinear corrections from halofit?

Antony Lewis · Posted: December 12 2006

Not by default, but you can set do_nonlinear = 2 in the .ini file to add corrections.

Sudeep Das · Posted: March 01 2007

Antony Lewis · Posted: March 01 2007

Probably not using high enough k_eta_max_scalar ? (note CMB lensing for non-BB is insensitive to the high l part of the lensing potential power spectrum; you need k_eta_max_scalar much higher to get the lensing potential accurately than you do to get the lensed C

l

accurately)

Gabriela Calistro Rivera · Posted: August 15 2011

Hello,

I'm simulating the lensed CMB in a similar way as Lenspix for my Bachelor Thesis.
Using the HEALPix routine synfast I have calculated the gradient of the lensing potential given by CAMB and as next the C

l

dd

of the absolute value of the deflection angle. In the ReadMe file of CAMB, they say

C

l

dd

= [l(l+1)]

2

/(2

π

) Cl

Φ Φ

,

where the C

l

dd

given as output here is equivalent to (l(l+1)) /(2

π

) * C

l

(computed)

dd

, which is my computed deflection angle power spectrum, right?.

But if I plotting this relation, I get a great difference between both! (uploaded figure plot4.eps).

I don't understand the problem, since it seems that my results of the deflection angles are right (going on with the remapping, the produced lensed temperature power spectra fits very well with the theoretical of CAMB).

I wonder if I have a false interpretation of the information given in the ReadMe?

Thanks for the help in anticipation!

Gabriela

Antony Lewis · Posted: August 17 2011

"absolute value of the deflection angle"? You don't want $|\nabla\psi|$ , but the power spectrum of the gradient (E)-mode part of spin−1 harmonic transform of the map of $\nabla\psi$ (see e.g. appendix of astro-ph/0502469)