Résumé / Abstract Seminaire_IAP
« Cosmology with Galaxy Clusters: from 'Weighing the Giants' to future surveys »

Anja von der Linden
Dept. Earth Space science, State Univ. New York (Stony Brook, New York, Etats-Unis d'Amérique)

Surveys of galaxy clusters provide a sensitive probe of cosmology by measuring the evolution of the halo mass function. However, already current cluster surveys are systematically limited by uncertainties in the relation between cluster mass and observables (e.g. X-ray luminosity, cluster richness, SZ decrement). The most promising methods to constrain the mass-observable relation employ weak gravitational lensing for the absolute mass calibration, and low-scatter mass proxies (available from X-ray observations) for the shape and scatter. I will discuss the "Weighing the Giants” (WtG) project, which measured accurate weak lensing masses for 51 clusters, and utilizes targeted X-ray observations of 90 clusters to measure gas mass as low-scatter mass proxy. From a sample of ~200 clusters selected from the ROSAT All-Sky Survey, WtG places some of the tightest constraints on a number of cosmological parameters, including the dark energy equation of state, neutrino masses, and modified gravity. Furthermore, when adopting the WtG mass calibration, the results from Planck CMB temperature anisotropies and Planck cluster counts are consistent without invoking the need for new physics. These results bode extremely well for future cluster surveys with weak-lensing-quality imaging over large areas, such as LSST and Euclid.
vendredi 5 avril 2019 - 11:00
Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris
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