Cluster Shear Testing Program (ClusterSTEP) Workshop

  • Tuesday May 18, 2010 through Friday May 21, 2010

  • The Center for Cosmology and Astro-Particle Physics (CCAPP) at The Ohio State University (OSU) is holding a Cluster Shear Testing Program (ClusterSTEP) Workshop in Columbus, Ohio on May 18-21, 2010.

  • Clusters of galaxies are the largest bound structures in the Universe and contain a wealth of cosmological information. The number density of galaxy clusters as a function of their mass and redshift is directly related to cosmological parameters, hence there is great interest in measuring this function to the highest possible precision. Weak gravitational lensing provides a powerful tool for these measurements, as it is sensitive to the total amount of matter of a cluster (dark and luminous) and does not rely on any other physical assumptions.

  • However, currently the desired precision from weak lensing mass constraints is hampered by several technical difficulties and it is the purpose of this workshop to address several of these. In particular, we will analyze 10 highresolution ray-tracing cluster images using various weak lensing pipelines.

  • The image quality corresponds to that expected from the DES survey, and were produced using the DES simulation pipeline at Fermilab. In addition, we discuss problems in cluster weak lensing which occur after obtaining a shear catalog, such as magnification bias, impact of photo-z measurements, contamination of foreground/cluster galaxies.



  • Preliminary agenda of the workshop:

  • • Detailed work on weak lensing pipelines such as
          a) imcat
          b) lensfit
          c) imcat+shapelets combined pipeline
  • • Developing PSF-models for 10 DES-like cluster images, obtained from ray-tracing simulations
  • • Comparing PSF models and results from different pipelines
  • • Calculate+compare shear profiles using shape measurements from different pipelines
  • • Discuss magnification bias, impact of photo-z measurements, contamination of foreground / cluster galaxies, and their impact on measuring the cluster mass function. Ideally we want to suggest possible tests/solutions to these issues coming from the ClusterSTEP simulations.

  • Please contact host Tim Eifler if interested in attending.
  • There were 5 participants