Language/ Langue
english. .français


Planck-Herschel 2yr post-doc (June 2012 - still open)
Applications are invited for a two-year position dedicated to 1) the photometric cross-calibration between Herschel and Planck, and more specifically between the SPIRE and HFI instruments and 2) the study of the galactic cirrus and cosmic infrared background diffuse emissions. Herschel is an ESA space observatory sensitive to the far infrared and submillimetre wavebands with very diverse scientific objectives on dedicated regions of the sky; Planck is an ESA space mission designed to observe the anisotropies of the cosmic microwave background over the entire sky.  The SPIRE and HFI instruments have two channels with very close bandpasses (near 350 and 500 microns), where the cross-calibration between SPIRE and HFI can be checked very accurately even if the angular resolution is quite different (5 arcmin for HFI versus 20 arcsec for SPIRE).

Planck/HFI primary photometric calibration is an extended source calibration. At high frequencies, the extended calibration is provided by the FIRAS/COBE observations while at low frequencies the orbital dipole is used. Point source calibration is then generated from the extended source calibration knowing the main beam and the spectral transmission for each detectors.  On the contrary, Herschel/SPIRE primary photometric calibration is a point source calibration, done mostly using planets. Neptune is the primary photometric calibration target, and extended calibration is then generated using the main beam. The goal is to compare the two photometric calibrations, quantify the error bars on the comparison and understand the remaining discrepancies. For the diffuse emission, same regions of the sky will have to be considered, from low to high brightnesses to check for any brightness dependency of the results.

At the frequencies of interest for the cross-calibration, the main astrophysical diffuse components are the galactic cirrus and cosmic infrared background. The research project of the applicant will include a study of the emission of these components, in particular their power spectra. The accurate modeling of the power spectra of these components is important for an optimal extraction of the cosmological parameters for Planck.

The successful applicant will work inside the Planck consortium to have privileged access to the HFI data. For SPIRE, some data are still in the public domain but a close connection with the consortia is desirable to get fully-processed maps, and a collaboration with the calibration team is necessary for the Neptune observations.

Applicants should submit an application letter,  a curriculum vitae and arrange for 2 letters of reference. The documents have to be sent to and The appointment is expected to start as soon as possible. Full consideration will be given to applications received by July 30th 2012.

The successful candidate will work at the Institut d'Astrophysique Spatiale (IAS) in Orsay, which is conveniently located 30 min from Paris, in a nice campus. The position includes the full access to the french healthcare system (medical and dental, maternity, etc) and 45 days of vacation/year. If applicable: 12 days for child sick leave and access to child daycare in the campus during vacations.