CAMB: Covariance of Galaxy Count Angular Power Spectrum

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
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Luca Suter
Posts: 5
Joined: October 06 2023
Affiliation: UniGe

CAMB: Covariance of Galaxy Count Angular Power Spectrum

Post by Luca Suter » December 12 2023

Hey,

I need to calculate the covariance of my C_l's at two seperate redshifts. I was told CAMB had a function for this specifically where all I had to do was plug in the two redshifts but after looking through the documentation I cannot seem to find it. Is there such a function? If not what would be the best way for me to complete this task?

The ultimate goal of this is to calculate the Fisher matrix and find the errors on my parameters.

Would love any feedback!
Luca

Antony Lewis
Posts: 1943
Joined: September 23 2004
Affiliation: University of Sussex
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Re: CAMB: Covariance of Galaxy Count Angular Power Spectrum

Post by Antony Lewis » December 12 2023

You can get auto and cross-spectra of any number of redshift windows - see box 37 of
https://camb.readthedocs.io/en/latest/CAMBdemo.html

Luca Suter
Posts: 5
Joined: October 06 2023
Affiliation: UniGe

Re: CAMB: Covariance of Galaxy Count Angular Power Spectrum

Post by Luca Suter » December 12 2023

Thank you for responding! Just so it's clear for me, the "W1XW2" would be the covariance that I am asking for? I would then ask CAMB to extract that array and it would the covariance of my two redshift bins?

Antony Lewis
Posts: 1943
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

Re: CAMB: Covariance of Galaxy Count Angular Power Spectrum

Post by Antony Lewis » December 13 2023

Yes (but not to be confused with the covariance of the power spectra of the two bins)

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