Workshops > Accounting for the uncertainties, from the laboratory to the observations, through the model

Accounting for the uncertainties, from the laboratory to the observations, through the model

Organisers: Frédéric Galliano (frederic.galliano@cea.fr), Karine Demyk (karine.demyk@irap.omp.eu), Pierre Gratier (pierre.gratier@u-bordeaux.fr)

Wednesday, 26 October 8:30-12:00

Summary:

An accurate estimate of the uncertainties is essential in all empirical sciences. Yet, when using a model to interpret observations, there are numerous layers of uncertainties that affect the final estimate of the physical quantities, and that are difficult to track and account for. This is particularly important for ISM studies, as our models often contain microphysical quantities that have been measured in the laboratory (cross-sections, reaction rates, etc.) and are put into a radiative transfer framework. In addition, observations are frequently corrected using external models that have their own set of assumptions and errors (extinction correction, contamination subtraction, etc.). Overall, improperly estimated uncertainties could change the outcome of a study and jeopardize our assessment of the reality of a phenomenon. This will become more important in the future, as we will see an increase in the accuracy of measurements, in the amount of heterogeneous data to analyze and in the complexity of models.

The goal of this workshop is to initiate a dialogue between laboratory experimenters, observers, modelers and astrostatisticians about this question. We will discuss a few scientific cases where the estimate of uncertainties is instrumental. We will highlight the different aspects that we need to take into account: (i) the microphysical quantities; (ii) their propagation through the model; (iii) the observations; (iv) their correction; and (v) the fit. We will emphasize the need to better characterize the errors by estimating their statistical and systematic components, their non-gaussianity, and their correlations. We will call for contributions from the audience. We are interested in discussing particular use cases where there is either a need for clarifying different sources of uncertainties or where original solutions to account for them have been found. A large fraction of this workshop will be devoted to discussions between participants. We hope, in the end, to delineate a few good practice suggestions and simple solutions to implement them. A summary of this workshop will be written by the organizers and will be available via the PCMI newsletter.