CAMB: Use of Halofit in Matter Transfer functions

Use of Healpix, camb, CLASS, cosmomc, compilers, etc.
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Emily Tyhurst
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Joined: February 26 2020
Affiliation: Canadian Institute for Theoretical Astrophysics
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CAMB: Use of Halofit in Matter Transfer functions

Post by Emily Tyhurst » February 26 2020

I've been unable to find a clear-cut answer for this in the CAMB notes, so I figured it would be faster to ask here.

Do the matter transfer functions for CAMB make use of nonlinear empirical information from HALOFIT, or are they numerical Boltzmann solutions based on the parameters only? I've been looking at the analytical solutions in astro-ph/9709112 ; but it's not clear to me if that's the only thing CAMB is giving me.

If there's a version split, I'm interested in what's happening for the latest version and for that of the April 2014 (ie. hosted on https://lambda.gsfc.nasa.gov/toolbox/tb_camb_form.cfm ).

Thanks for the help!

Antony Lewis
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Affiliation: University of Sussex
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Re: CAMB: Use of Halofit in Matter Transfer functions

Post by Antony Lewis » February 27 2020

It either returns the linear Boltzmann theory spectrum, or the the nonlinear spectrum modelled calculated from the linear solution using one of the supported versions of halofit/HMCode. It does not use direct fitting formulae like Eisenstein and Hu.

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