Alex Malz (NYU), Fed Bianco (NYU) and I discussed a possible hierarchical model for doing supernova cosmology in the face of uncertain supernova classifications and start times, which will be generic in time-domain surveys that are sparse or not designed with supernovae in mind. We started with a pretty complicated graphical model, but we were able to pare it down and then a bit more, and finally got to something awesomely simple: If we represent all supernova types with a bag of templates, and each has some prior pdf for peak brightness, then we can simultaneously model the cosmological parameters, the type probabilities, the peak-brightness distributions, and the photometry of every supernova, no matter what the bandpasses and cadences. The cool thing is that this project can (almost) be assembled from off-the-shelf parts, in the form of sub-systems of other supernova projects. And the project should create new opportunities for projects and legacy data sets.
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