LAM oca fermilab

INSU


DAFT/FADAS

A treasure trove for cluster science and weak lensing tomography

Last update September 3rd, 2010 

The DAFT/FADAS program is a combined US/France effort aiming at combining HST-archives with ground-based photometry,  to produce the largest weak lensing surveyof rich z = [0.4,0.9] clusters and photometric redshifts for the field galaxies. The primary goal is to make a geometrical determination of the nature of Dark Energy, using weak lensing tomography, applied to the background galaxies around the clusters. By obtaining redshifts and shear measurements of about 20,000 galaxies, we will gain enough statistics to measure the equation of state of Dark  Energy to a good enough accuracy to act as a training set for future Magnified Weak Lensing Tomography surveys. In addition, mass models plus spectroscopic and photometric redshifts will make the data base a treasure trove for cluster and galaxy evolution science. Some of the background galaxies will be magnified enough to lead to the discovery of galaxies at redshifts  above 6.

The DAFT/FADAS team is lead by Prof. Mel Ulmer (Northwestern University) and Prof. Doug Clowe (Ohio State University) on the US side, and Christophe Adami (LAM/Université de Provence) in France. The whole team list is available here

Latest News :

The figures below are from  Guennou et al. (2010) and show 1) the zphot-zspec relation, showing the overall quality of zphot measurement 2) the precision of the zphot measurement as a function of zphot for different magnitude ranges, showing that within our range of study the precision is better than 0.2  3) an image of the main arcs around LCDCS 0504

Publications :    

Refereed papers :
- Guennou et al., 2010, A&A 523, 21 (astro-ph ) : Photometric redshifts along lines of sight of clusters in the z=[0.4,0.9] interval
- Guennou et al., A&A, 537, 64 : Intracluster light in clusters of galaxies at redshifts 0.4<z<0.9
- Murphy et al., ApJ, in preparation : Analyzing deep HST Imagery of 10 hig-redshift galaxy cluster with weak lensing.  
- Clowe et al., ApJ, in preparation : Weak Lensing tomography along lines of sight of clusters in the z=[0.4,0.9] interval 
- Johnston et al., in preparation :  Dealing with non-linearity in weak lensing tomography in the direction of rich clusters

Conference presentations
   - Guennou et al., Poster at GLCW: An alternative method to constrain dark energy: Weak Lensing Tomography in the Direction of Rich Clusters  
   - Murphy et al. , Poster  at GLCW: "Weak Lensing with the Hubble Space Telescope"
   - Mazure et al., Poster at "CL J2010: from Massive Galaxy Formation to Dark Energy", Japan, 2010: GALAXY CLUSTER SEARCHES IN THE CFHTLS AND APPLICATIONS
   - Durret et al., Poster at "Galaxy clusters: observations, physics, and cosmology", Garching, 2010: "First results of the FADA (French American DArk energy) Survey"

Ph. D. Thesis : 

- L. Guennou (LAM)  :  Line of sight caracterization and photometric redshifts
- K. Murphy (Ohio University)  :  Weak lensing tomography
- N. Martinet (IAP)  :  Weak lensing analysis of HST DAFT/FADAS images

Status of the project :

More than 54 nights have been granted on 4 meter class telescopes for the ground based multi-band imaging. The detail of the observations granted is available here

Internal links : Observations organization page

Final data access

 

This work has been supported in part by a grant for the U.S Department of Energy DE-FG02-08ER41567, as well as institutional support from in the U.S.: Northwestern University, Ohio University, Fermi National Accusatory Laboratory and Alfred P. Sloan Foundation, in Europe: Laboratoire d'Astophysique de Marseille, Institut d'Astophysique de Paris, PNCG and the University of Leiden and in Brazil : IAG ans UESC. Telescopes used for the ground based data include the VLT, CTIO/Blanco, CTIO/SOAR, KPNO/WIYN, CFHT, TNG, and WHT.  The space based data come from HST and Spizter.