BBN-Consistency¶
Compute consistent Helium fraction from baryon density given BBN
File |
utility/bbn_consistency/bbn_consistency.py |
Attribution |
CosmoSIS Team |
URL |
|
Citations |
Comp.Phys.Commun.178:956-971,2008 |
The Big Bang Nucleosynthesis model describes how the light elements were generated in the primordial universe. For a given value of Omega_b h**2 and number of neutrinos the theory can predict the helium abundance.
This module sets the helium mass fraction (YHe) from the mean baryon density (ombh2) and number of neutrinos (delta_neff), based on a table interpolation from those calculations.
This module should go into the pipeline after consistency and before any physics modules. It’s effectively an optional consistency module.
Assumptions¶
Standard Big Bang Nucleosynthesis
ombh2 within the range of the input data
Setup Parameters¶
Name |
Type |
Default |
Description |
|---|---|---|---|
data |
str |
included |
Filename for ombh2,DeltaN,YHe data. ( file) |
input_name |
str |
delta_neff |
Which parameter to start from, either massless_nu or delta_neff |
Input values¶
Section |
Name |
Type |
Default |
Description |
|---|---|---|---|---|
cosmological_parameters |
ombh2 |
real |
Physical matter density parameter |
|
delta_neff |
real |
0.0 |
Extra contribution to neutrino number density (if input_name == delta_neff) |
|
massive_nu |
real |
Effective number of massive neutrinos (if input_name == massless_nu) |
||
massless_nu |
int |
Number of massless neutrinos (if input_name == massless_nu) |
Output values¶
Section |
Name |
Type |
Description |
|---|---|---|---|
cosmological_parameters |
yhe |
real |
Cosmological helium fraction |