Cosmomc Matter Power Spectrum

Use of Healpix, camb, CLASS, cosmomc, compilers, etc.
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Davide Pietrobon
Posts: 7
Joined: January 11 2007
Affiliation: University of Rome, Torvergata

Cosmomc Matter Power Spectrum

Post by Davide Pietrobon » April 04 2008

Hi Antony!

I'm studying the matter power spectrum. I discovered that actually mpk.f90 marginalizes over the amplitude of the power spectrum. What do you suggest if I need to fit also the normalization? Can I simply turn "Q_marge = F"? I tried to do that, but apparently the power spectrum output is a nonsense.

The reason why cosmomc doesn't care about the amplitude depends on the bad quality of the data?

Can you help me?

Thank you very much

Davide

Antony Lewis
Posts: 1501
Joined: September 23 2004
Affiliation: University of Sussex
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Re: Cosmomc Matter Power Spectrum

Post by Antony Lewis » April 04 2008

CosmoMC assumes an unknown scale-independent bias between what you observe (e.g. biased galaxies) and the matter power spectrum. As well as marginalizing over b^2 with flat prior it can also marginalize over Q.

Davide Pietrobon
Posts: 7
Joined: January 11 2007
Affiliation: University of Rome, Torvergata

Cosmomc Matter Power Spectrum

Post by Davide Pietrobon » April 04 2008

Thank you very much, Antony.

I also went through the papers cited in mpk.f90 and that clarified things.

Thank you again

Davide

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