planck_sz¶
Prior on sigma_8 * Omega_M ** 0.3 from Planck SZ cluster counts
File |
likelihood/sz/sz.py |
Attribution |
Planck collaboration (measurement) |
CosmoSIS team (code) |
|
URL |
|
Citations |
arXiv:1303.5080, Planck 2013 results. XX. Cosmology from Sunyaev-Zeldovich cluster counts |
This small module was written for CosmoSIS.
CMB data like that from Planck can be used to make counts of clusters using the Sunyaev-Zeldovich effect, in which hot gas in the clusters scatters CMB photons and causes a decrement (below 217 GHz) or increment (above 217 GHz).
The number of clusters in the universe of a given mass is sensitive to the mass density and the overall amount structure in the universe. The full calculation is very involved, but in a LCDM universe with some assumptions about Halo behaviour it can be reduced to a constraint on sigma_8 * Omega_M ** 0.3
Assumptions¶
Planck SZ data
SZ signal Y - Mass relation calibrated from X-ray data
Flat LCDM
Tinker et al halo distribution
Setup Parameters¶
Name |
Type |
Default |
Description |
|---|---|---|---|
measured_value |
real |
0.764 |
Replace the standard value measurement sigma_8 * Omega_M ** 0.3 = 0.764 with a custom one for simulations |
Input values¶
Section |
Name |
Type |
Default |
Description |
|---|---|---|---|---|
cosmological_parameters |
omega_m |
real |
Matter density fraction at redshift 0 |
|
sigma_8 |
real |
Matter fluctuation dispersion down to 8 Mpc/h |
Output values¶
Section |
Name |
Type |
Description |
|---|---|---|---|
likelihoods |
SZ_LIKE |
real |
Gaussian likelihood value of supplied parameters |