Assigned ID: 906 ----- Attempting Submission 1 (Sat Feb 26 01:25:53 GMT 2011) ----- The standard cosmological paradigm, LCDM with Gaussian initial conditions, makes specific predictions for the abundance of high mass objects and for the evolution of this abundance with time. The existence of even a few very massive galaxy clusters at high redshift can falsify the model, if a robust connection can be made between the true mass of the systems and their observed properties. Hubble Space Telescope provides a unique opportunity to study the mass distribution of high redshift clusters via weak gravitational lensing. It has been argued that the recent discovery and confirmation, with HST lensing measurements, of a number of massive galaxy clusters at high redshift indicates tension either with the standard LCDM model --- potentially giving evidence for non-Gaussian initial conditions and probing the physics of inflation --- or with our current understanding of the mass calibration. However, these conclusions are uncertain due both to lack of statistics for theoretical calibration of the LCDM mass function at the highest end and due to uncertainty in the relationship between halo mass and various cluster observables at these redshifts. We propose to use large-volume simulations, probing ~ 2000 Gpc^3, to characterize the statistics of these massive systems at high redshift (z > 1), and to perform high-resolution zoom-in simulations to study the mass calibration for these clusters in detail. These studies are essential to interpret the influx of HST followup of the most massive high redshift clusters detected in the SZ and X-ray, and to confirm or deny evidence for deviations from LCDM from these data.

COSMOLOGY 12 Small false 0.0 0.0 false false true false SUPPORTED