EUCLID NIP

EUCLID is a Cosmic Vision Survey Mission being proposed by ESA with the primary goal to map the geometry of the dark universe, to characterize dark energy and study dark matter. MPE is involved in the efforts of definition and design of a near infrared imaging photometer (NIP) to be flown on board the EUCLID satellite.

The EUCLID project http://www.chalonge.obspm.fr/Paris08_Kessler.pdf undergoes currently an assessment study: on system level at the European space industry and at instrument level at consortia formed by scientific institutes of 6 ESA member states and US contributions.

DUNE – the Dark Universe Explorer – was a M-class mission proposal submitted to ESA’s Cosmic Vision Call by A. Refregier et al. from CEA Saclay (France). DUNE was designed as a wide field imager consisting of a 1.2 m telescope with a combined visible/NIR field of view of 0.5 deg² each to carry out an all sky survey in one visible (R+I+Z) and three NIR bands (Y, J, H) in drift scanning mode (1.1 deg/hour). DUNE was optimized for the method of weak gravitational lensing, i.e. the purpose of measuring the impact of dark energy on both the distance-redshift relation and the growth of cosmic structure. A launch date in 2017 was foreseen, the satellite being placed into a geosynchronous orbit. The EUCLID CDF Study performed by ESA and finished in June 2008 merged the two mission proposals DUNE and SPACE (spectroscopic all-sky cosmology explorer) into the combined concept EUCLID.

The EUCLID satellite payload consists in the current baseline of a 1.2 m Korsch telescope, a 3 mirror common opto-mechanical assembly and 3 scientific instruments dedicated to visible imaging (VIS), near infrared photometric imaging (NIP) and to near infrared spectroscopy (NIS). Passive cooling is foreseen to provide 170 K resp. 140 K for the focal plane detectors. Two observation modes are presently under study: step and stare versus continuous scanning (all-sky survey covering 20 000 deg²). The payload mass is about 660 kg including 300 kg for the three instruments with a possible launch into a L2 orbit at the end of 2017 and about 5 years lifetime.

NIP is the near infrared imaging photometric channel on board the payload. The assessment study on both imaging channels VIS and NIP – optimized for the weak lensing measurements – is led by CEA Saclay (France) and is done by a consortium of several institutes of 6 ESA member states and the US. CEA has nominated Alexandre Refregier as PI for the two imaging channels VIS and NIP.

The assessment study on NIP is led by MPE (Ralf Bender is Co-PI) in cooperation with MPIA Heidelberg. Further contributions to NIP are coming from ATC (UK), CEA (France) and from JPL (USA) for the FPA. The German part of the study will be partly funded by DLR. Results of the instrument studies should be available end of October 2009 achieving a technical definition of the science instruments consistent with the other elements of the mission concept.

Characteristics of the proposed 3 EUCLID instruments

Photometric redshift performance for a DES-like ground survey with and without the

DUNE NIR bands (J,H). The deep NIR photometry, which is only achievable in space,

results in a dramatic reduction of the photometric errors and of catastrophic failures,

which is needed for the weak lensing tomographic analysis, BAO, clusters and ISW

(Abdalla et al. 2007, MNRAS). (Pictures, table and figure captions are taken from the documents mentioned below)

Documentation:

ESA EUCLID CDF Study Report CDF-73(A), June 2008

DUNE, The Dark Universe Explorer,

proposal submitted to ESA’s Cosmic Vision 2015-2025 Call, Refregier, A. et al, 2007

http://www.springerlink.com/content/90l368r437334105/fulltext.html

NIP Study Team at MPE:

Mario Schweitzer Ralf Bender Frank Eisenhauer Reiner Hofmann Reinhard Katterloher

Contact person:

Dr. Mario Schweitzer, Schweitzer@mpe.mpg.de