Planck Forecasts using CosmoMC

[Alan Zablocki]

Can someone explain to me how you would go about calculating forecasts for Planck using CosmoMC. I understand that the default setting for CosmoMC is to use actual datasets to explore the parameter space, for instance:

cmb_numdatasets = 1
cmb_dataset1 = WMAP
cmb_dataset_SZ1 = data/WMAP_SZ_VBand.dat
cmb_dataset_SZ_scale1 = 1

Does this mean that I have to create a full-on mock dataset to do a similar calculation for Planck?

Is there a routine that does this for Planck within CosmoMC and if so how/where do I initiate it? I have looked at the source files and there is a file called Planck_like.f90, but again am not sure how it is initiated within CosmoMC.

I would think I need to create some fiducial Cls, and have a 4x4 covariance matrix assuming some beam errors for Planck.

In looking at calclike.f90, I noticed that there is also an option to give a generic likelihood function and use CosmoMC as a generic sampler,would that be a way to go about this, and if so how would you got about doing this? How does one define likelihood and experimental errors?

Thanks!

[Antony Lewis]

For simple full-sky isotropic-noise forecasts see eg.

http://cosmocoffee.info/viewtopic.php?t=231

(and possibly search on cosmocoffee for other relevant topics)

The Planck_like module has more realistic/complicated non-exact likelioods for handling low/high L data with correlated errors etc.

The Readme describes the steps to use CosmoMC as a generic sampler.