For people who already played with MCMC, we propose a collaborative work on testing the robustness of the sigma8 measurements with local data (SN,BAO). A group of people interested by this subject forms and different points are assigned to evryone. If some interesting results are found it may even lead to a paper.
This work must be performed on mardec
1. Parameter file
- parameters: Put explicitly each of the 6 LCDM parameters to be used (fixing most of them) and add some massive neutrinos (0.06 eV is the lower bound)
- Model: from the camel documentation construct a parFile including both the latest BOSS-DR12 and JLA (SN1a) measurements
- MCMC extras:
is not a direct parameter in CLASS so you need to add it as an extra parameter.
2. Results
2.1 Neutrinos mass
why 0.06 eV? this is the lowest bound coming from neutino oscillations experiements but no theoretical reasons lightest neutrino is exacty 0. What if sum raised to 0.1 eV?
2.2 Reionization
those data do not constrain teh reionization. add a prior coming from Planck and see if there is an effect.
2.3 non-linearity
does this change something?
2.4 H0 prior
include the Riess result
2.5 As or log(As)?
sigma8 is very linked to As. Should we add a flat prior on As or logAs?
2.6 S8 indirect prior effect
null likelihood
only sample from the prior (neeeds coding into CAMEL)
directly sampling on s8
the latest CLASS version allows to define sigma8 as a base parameter but looks like CAMEL is crashing with it: check on DEC.
profile likelihood
build the profile
3. Weak-lensing
Currently no WL likelihood is included in CAMEL: want to contribute?
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