Hello,
I have started working with CAMB only recently and consequently have some questions.
1.) I have already managed to get the matter power spectrum for different values of the density parameters [tex]\Omega_\text{c}[/tex] and [tex]\Omega_\text{m}[/tex], but there is one problem: Setting the density parameter [tex]\Omega_\text{c}=0[/tex] the programm compains about crazy values. Of course, this value isn't realistic at all but I need the power spectrum for a universe containing only baryons and no cold dark matter. Is there any possibility how to avoid this error message?
2.) Besides this I also need the dimensionless power spectrum [tex]k^3P_\delta(k)[/tex] where [tex]P_\delta(k)[/tex] is the matter power spectrum. What do I have to do to get it?
3.) Furthermore I need the gravitational potential [tex]\Phi(a)[/tex] as well as the density contrast [tex]\delta(a)[/tex]. Where do I get them from?
Since I am still very little versed I ask you to respond as fully and understandable as possible for me as a beginner. Of course I have read the CAMB notes but they are not very enlightening from my questions.
Thanks,
Maximilian
Dimensionless power spectrum and density contrast
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- Posts: 1
- Joined: July 25 2014
- Affiliation: Technische Universität München
Dimensionless power spectrum and density contrast
For 2.), CAMB should give you a file called something like ...matterpower.dat. The first column is [tex]k/h[/tex] in units of [tex]\rm{Mpc}^{-1}[/tex]. The second column is [tex]h^3P_\delta(k)[/tex] in units of [tex]\rm{Mpc}^3[/tex], where [tex]P_\delta[/tex] is the dimensionful power spectrum.
For 3.), if you want the power spectrum of the potential, presumably you just need to use the Poisson equation to translate.
For 3.), if you want the power spectrum of the potential, presumably you just need to use the Poisson equation to translate.