Definition of dgpi (/camb/equations.f90)

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Alex Zucca
Posts: 4
Joined: June 24 2015
Affiliation: Simon Fraser University

Definition of dgpi (/camb/equations.f90)

Post by Alex Zucca » February 17 2016

Hi Antony,

I have a very simple question, but I want to be sure. You define dgpi in /camb/equations.f90 as

[tex]\text{dgpi} = \sum 8 \pi G a^2 \rho_i \Pi_i[/tex]

So, in Newtonian gauge, I should write the Einstein equation as

[tex]k^2 (\phi - \psi) = 12 \pi G a^2 \sum (\rho + P )\sigma = \frac{3}{2} \text{dgpi}[/tex].

Am I wrong?

Thanks,
Alex

Antony Lewis
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Joined: September 23 2004
Affiliation: University of Sussex
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Re: Definition of dgpi (/camb/equations.f90)

Post by Antony Lewis » February 17 2016

Not sure about the factor of 3/2, e.g. see the second equation on p12 of the CAMB notes.

Alex Zucca
Posts: 4
Joined: June 24 2015
Affiliation: Simon Fraser University

Definition of dgpi (/camb/equations.f90)

Post by Alex Zucca » February 18 2016

Great, thanks!

Alex

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