Dodelson's plots

[ivan rodriguez-montoya]

Hi all

In the Dodelson's textbook (Modern Cosmology), a very useful tool is to study the behavior of the gravitational potential in newtonian gauge (see e.eg. fig. 7.2).

Is it possible to print the evolution of the gravitational potential using CAMB?

I appreciate your advice.

[Antony Lewis]

You can easily modify the code to print it out; e.g. in subroutine output in equations.f90 the Weyl potential \phi (~Newtonaian potential) is calculated to be used for lensing, so you can just instead put that in a write statement along with k and tau (or a).

[ivan rodriguez-montoya]

Thank you Antony,

To be completely explicit, I add this lines to the subroutine output

Code: Select all

phi = -(dgrho +3*dgq*adotoa/k)/(k2*EV%Kf(1)*2) 
open(5,file='ISW.dat',form='formatted',status='old',POSITION='APPEND')
write (5,FMT=250) a, k, phi, ISW
250 FORMAT (E20.8, E20.8, E20.8, E20.8)
close(5)

Just one doubt: is it normal to obtain ~[tex]10^{-3}[/tex] as the initial value of [tex]a[/tex]?
In any case, is it possible to print from lower values of [tex]a[/tex]?

Thanks again!!

[Antony Lewis]

The sources are usually only output once the contribution to the CMB is non-negligiible. You can modify CalcScalarSources in cmbmail.f90 (as per the commented code) to outut things over a larger range or with different spacing.