sigma_cpp¶
Compute anisotropy dispersion sigma(R,z) in cpp
File |
boltzmann/sigma_cpp/sigma_cpp.py |
Attribution |
Michel Aguena |
URL |
sigma(R,z) is the variance of cosmic density fluctuations on scales down to 8 Mpc/h.
In Fourier space is given by \(sigma(R,z) = \int_0^\infty W^2(k R) k^2 P(k,z) / (2 \pi)^2 dk\)
The P(k,z) used could in general be linear or non-linear, but usually when people say sigma they mean the non-linear variant.
Assumptions¶
minimal assumptions; sigma computed directly from P(k,z)
Setup Parameters¶
Name |
Type |
Default |
Description |
|---|---|---|---|
zmin |
real |
Minimum redshift to generate values for |
|
zmax |
real |
Maximum redshift to generate values for |
|
dz |
real |
Output redshift sample spacing |
|
z |
real |
Values of redshift to generate values for, overwrites (zmin, zmax, dz) |
|
logmmin |
real |
Minimum value of log10(Mass) [in M_sun/h] to generate values for |
|
logmmax |
real |
Maximum value of log10(Mass) [in M_sun/h] to generate values for |
|
dlogm |
real |
log10(Mass) spacing |
|
logm |
real |
Values of log10(Mass) [in M_sun/h] to generate values for, overwrites (logmmin, logmmax, dlogm) |
|
rmin |
real |
Minimum scale R in Mpc/h to generate values for |
|
rmax |
real |
Maximum scale R in Mpc/h to generate values for |
|
dr |
real |
Scale R spacing |
|
r |
real |
Values of R [Mpc/h] to generate values for, overwrites (rmin, rmax, dr) |
|
matter_power |
str |
matter_power_lin |
Name of section to get P(k,z) from, e.g. matter_power_lin, matter_power_nl |
use_m |
bool |
False |
Uses the mass values as a base for the computation instead of R |
verbose |
bool |
False |
Prints details of the computation |
Input values¶
Section |
Name |
Type |
Default |
Description |
|---|---|---|---|---|
matter_power_lin |
k_h |
real 1d |
Sample values of linear spectrum in Mpc/h. Section name specified by parameter in ini file. |
|
z |
real 1d |
Redshift of linear spectrum samples. Section name specified by parameter in ini file. |
||
P_k |
real 2d |
Linear spectrum in (Mpc/h)^{-3}. Section name specified by parameter in ini file. |
Output values¶
Section |
Name |
Type |
Description |
|---|---|---|---|
sigma_cpp |
R |
real 1d |
Scale R of output samples in Mpc/h |
logm |
real 1d |
log10(Mass) samples [in M_sun/h]; matches R |
|
z |
real 1d |
Redshift of output samples |
|
sigma |
real 2d |
Variance sigma(R,z) of samples |