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cosmosis / DES SV Likelihood

Using the DES SV Likelihood

The Dark Energy Survey Science Verification likelihood for the shear two-point measurements released on 21 July 2015 are now available in CosmoSIS, a package for parameter estimation in cosmology.

Here are the steps to using it.

1. Install CosmoSIS

Follow these instructions to install cosmosis (the download may take a while, depending where you are - sorry).

2. Get the development version

At the moment the DES likelihood is only available in the "development" (bleeding edge) branch of CosmoSIS, though this will change soon.

Run the commands:

source config/setup-cosmosis
update-cosmosis --develop
make clean

you will get the most up-to-date cosmosis version.

3. Test-run the likelihood

Then you can run an example of the DES-SV cosmic shear likelihood by doing:

cosmosis examples/des_sv.ini

4. Explore further

This will just run a test, calculating the likelihood at a single point in parameter space. To explore the likelihood you can change to a real sampler - details are in examples/des_sv.ini, as are details on what is happening in the likelihood and how to modify and experiment with it. You can also see examples/des_sv_values.ini for the input parameters, and examples/des_sv_priors.ini for the priors.

If you are new to CosmoSIS please see our front page for tutorials and reference information.