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WEAK LENSING CALIBRATED<i>M</i>-<i>T</i>SCALING RELATION OF GALAXY GROUPS IN THE COSMOS FIELD

K. KettulaDepartment of Physics, University of Helsinki, Gustaf Hllstrmin katu 2a, FI-00014 Helsinki, Finland;A. FinoguenovDepartment of Physics, University of Helsinki, Gustaf Hllstrmin katu 2a, FI-00014 Helsinki, Finland;R. MasseyInstitute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE, UKJason RhodesCalifornia Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USAHenk HoekstraLeiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333-CA Leiden, The NetherlandsJames E. TaylorDepartment of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, CanadaP. SpinelliInstituto de Astronomia, Geofsica e Cincias Atmosfricas (IAG), Rua do Mato, 1226 Cidade Universitria 05508-090, So Paulo, SP, BrazilMasayuki TanakaNational Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, JapanO. IlbertLAM, CNRS-UNiv Aix-Marseille, 38 rue F. Joliot-Curis, F-13013 Marseille, FranceP. CapakSpitzer Science Center, 314-6 Caltech, 1201 East California Boulevard Pasadena, CA 91125, USAH. J. McCrackenInstitut d'Astrophysique de Paris, UMR 7095, 98 bis Boulevard Arago, F-75014 Paris, FranceA. M. KoekemoerSpace Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

2013en

ABI

Annotatsiya

The scaling between X-ray observables and mass for galaxy clusters and groups is instrumental for cluster-based cosmology and an important probe for the thermodynamics of the intracluster gas. We calibrate a scaling relation between the weak lensing mass and X-ray spectroscopic temperature for 10 galaxy groups in the COSMOS field, combined with 55 higher-mass clusters from the literature. The COSMOS data includes Hubble Space Telescope imaging and redshift measurements of 46 source galaxies per arcminute 2 , enabling us to perform unique weak lensing measurements of low-mass systems. Our sample extends the mass range of the lensing calibrated M-T relation an order of magnitude lower than any previous study, resulting in a power-law slope of 1.48 +0.13 -0.09 . The slope is consistent with the self-similar model, predictions from simulations, and observations of clusters. However, X-ray observations relying on mass measurements derived under the assumption of hydrostatic equilibrium have indicated that masses at group scales are lower than expected. Both simulations and observations suggest that hydrostatic mass measurements can be biased low. Our external weak lensing masses provide the first observational support for hydrostatic mass bias at group level, showing an increasing bias with decreasing temperature and reaching a level of 30%-50% at 1 keV.

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DOI: 10.1088/0004-637x/778/1/74

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