RENOIR - Research for dark energy

Science activities related to the LSST project


Preparation of supernovae analysis

Contributions to the photometric processing chain

The LSST project will face the challenge of precision, in particular to limit the systematic errors associated with the various measurements by the cosmological probes and the challenge of the very large mass of data to be processed. The MPCC has thus committed itself to LSST to take part in meeting these two challenges by leveraging its expertise acquired or in the process of being acquired.

We are thus strongly involved in the use of data reduction software or we are working to improve algorithms and procedures for the discovery and photometric measurement of supernovae. We use the expertise acquired in this domain with SNLS using the LSST software to reprocess the SNLS images and reproduce a Hubble diagram more complete than the one published, not limited to the supernovae which have benefited from a photometric tracking. This work is carried out for a part using the IN2P3 computing center and thus participates in the implementation of official processing of LSST to CC (DRP). We also develop links and work with the LSST teams. This work is the subject of a thesis in progress.

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Calibration

The measurement of the Hubble diagram of the supernovae is limited, with current statistics, by systematic errors. In particular photometric calibration will be a key point. We have therefore started an activity on photometric calibration where we add external data to the internal data present in the survey. Several proposals in this direction exist for LSST, we focus on the use of the observations of the catalog Gaia for which we have links with experts. We also have an experimental participation in the implementation of observation of the DICE diode calibration project at the OHP, where we also have specific contacts.

Our participation finally combines these two aspects by setting up, in concert with the other participants of the working group SN DESC, a purely photometric analysis chain of a Hubble diagram. For this we intend to add our contributions and special expertise on the production of calibrated light curves to a classification expertise to study the control and reduction of systematic errors that taint such a Hubble diagram.