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Deep galaxy Evolution Survey in the near Infra-Red – DESIR

Submission summary

Our current understanding of galaxy evolution is primarily derived from many wide field optically selected surveys (SDSS, 2dF, CFHT-LS, VVDS, COSMOS). Because visible light (for z>1.4) and ultraviolet light (for z>7) of distant galaxies is redshifted into the near-IR bands, to make significant progress in understanding galaxy formation and evolution at higher redshifts we require deep, wide-field infrared-selected surveys. The DESIR (Deep galaxy Evolution Survey in the near Infra-Red) project proposed here aims to make a profound advance in our understanding of the formation and evolution of galaxies by exploiting 2 major near-infrared surveys where we have leading participation: 1) The WIRDS survey, a Franco-Canadian project (co-PI: Kneib), is using CFHT/WIRCAM camera to collect deep infrared imaging in J, H and K over a large fraction of the four CFHTLS deep fields and the COSMOS field. 2) The UltraVISTA project is an accepted ESO public survey (co-PI: Le Fèvre) to be executed on VISTA, a new highly efficient wide-field 4m-IR telescope that will see first light at the end of 2007. UltraVISTA will conduct extremely deep observations of the COSMOS field in 5 infrared bands: Y, J, H and K and a narrow-band filter at 1.19 micron that will target Lyman-alpha emitters at z~8.8. Building on these 2 observational projects, which will revolutionize our understanding of galaxy evolution at high redshift we are asking for funding, manpower (three 2-year postdocs) and resources (computing and travel) necessary in order to deliver reduced images and catalogues and lead the following key scientific investigations that are crucial to understanding galaxy evolution and formation. 1) Redshift distribution of faint galaxies: Without near-IR photometry, photometric redshift techniques are not reliable beyond redshifts of unity because of the lack of deep infrared data. Our new infrared data will be deep enough to probe the 4000 Angstrom break at 1<z<3, thus greatly improving the photometric redshift accuracy and reducing the number of 'catastrophic redshifts'. This will be critical to perform numerous galaxy evolution detailed below and weak lensing analyses underway in this field (cosmological constraints through cosmic shear analysis, mass mapping, group and galaxy lensing). 2) Tracing the growth of (stellar) mass: With WIRDS and UltraVISTA we will investigate this topic in detail by measuring, as a function of redshift, the luminosity function, luminosity density and correlation function of galaxies selected by stellar mass. At redshifts greater than unity, the crucial advantages of infrared for tracing the mass-dominant component of the stellar populations of galaxies have long been understood. However, no existing survey has the necessary area, depth, and supporting multi-frequency data to explore a wide dynamic range in mass in the redshift range 1<z<5. 3) Representative volumes to search for old massive galaxies and high redshift clusters: WIRDS and UltraVISTA surveys offer unique statistical probes of galaxy formation and evolution. Their large areal coverage (three square degrees in total) allows studying representative volumes of the high redshift universe, comparable to SDSS for the local Universe. We will thus be able to quantify the evolution of the oldest and most massive galaxies and rarest high redshift clusters at z>1.4-1.5 which correspond to the most crucial epoch in the history of galaxy formation and evolution. 4) The first galaxies: We now stand at the ultimate frontier in our quest to understand the end of the 'dark ages' and the formation of the first galaxies. The current situation is tantalizing; we know of a few hundred galaxies at z~6 and we have good evidence that reionisation took place at redshifts less than ten, but there currently exist only a very limited number of credible galaxy candidates at z>6.5. Reaching higher redshifts requires extremely deep near-infrared imaging of much larger areas and greater depths to enable effective Lyman-break and Lyman-alpha galaxy selection. UltraVISTA will be the first survey to provide a representative sample of galaxies at z>6.5. Although spectroscopic confirmation probably will have to wait until the launch of JWST and the ELTs, UltraVISTA's broad bands coupled with the available optical data in the targeted fields will allow a unique and efficient selection of these very distant galaxies. 5) Constraining galaxy formation models: By assembling the results from these galaxy evolution studies produced by French teams and our international collaborators in both WIRDS and the UltraVISTA project, and comparing with the state of the art numerical simulations that we are conducting in France with the Horizon project, we will bring an essential piece of information to better understand galaxy formation models by constraining the important physical process at play in the formation and evolution of galaxies.

Project coordination

Jean Paul KNEIB (Organisme de recherche)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.



Help of the ANR 346,000 euros
Beginning and duration of the scientific project: - 48 Months

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