CAMB: Matter power spectrum output
-
- Posts: 4
- Joined: August 09 2006
- Affiliation: University of Michigan
CAMB: Matter power spectrum output
Does anyone know whether the wavenumbers in CAMB matter power spectra are 2pi / (comoving distance) or 2pi / (some other distance)?
-
- Posts: 1944
- Joined: September 23 2004
- Affiliation: University of Sussex
- Contact:
Re: CAMB: Matter power spectrum output
Pretty much everything in CAMB is comoving. Note output matter power spectra are in h Mpc^{-1} units.
-
- Posts: 4
- Joined: August 09 2006
- Affiliation: University of Michigan
CAMB: Matter power spectrum output
Weird... it says in Peacock's Cosmological Physics that
Thanks for your help, and sorry if I'm misunderstanding things... I'm very new at this. :P
The [tex]\xi[/tex] I get from the CAMB output does have a fixed small-scale shape, which is consistent with it being in proper coordinates. However, it scales with redshift like [tex](1+z)^{\gamma-3}[/tex], which Peacock describes as "comoving evolution." Does comoving evolution have anything to do with comoving coordinates? If the length scale in CAMB is in comoving coordinates, why does it retain its small-scale shape for different redshifts, like it should in proper coordinates?Regarding [tex]\xi[/tex] as a density profile, its small-scale shape should... be fixed in proper coordinates, and its amplitude should scale as [tex](1+z)^{-3}[/tex].... Thus, with [tex]\xi \sim r^{-\gamma}[/tex], we obtain the comoving evolution [tex]\xi(r,z) \sim (1+z)^{\gamma-3}[/tex] (nonlinear).
Thanks for your help, and sorry if I'm misunderstanding things... I'm very new at this. :P