Browsing by Author "Pratt, G. W."

Now showing 1 - 3 of 3
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    Exploring the galaxy cluster-group transition regime at high redshifts Physical properties of two newly detected z > 1 systems
    (2011) Suhada, R.; Fassbender, R.; Nastasi, A.; Boehringer, H.; de Hoon, A.; Pierini, D.; Santos, J. S.; Rosati, P.; Muehlegger, M.; Quintana, H.; Schwope, A. D.; Lamer, G.; Kohnert, J.; Pratt, G. W.
    Context. Multi-wavelength surveys for clusters of galaxies are opening a window on the elusive high-redshift (z > 1) cluster population. Well controlled statistical samples of distant clusters will enable us to answer questions about their cosmological context, early assembly phases and the thermodynamical evolution of the intracluster medium.
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    First simultaneous optical/near-infrared imaging of an X-ray selected, high-redshift cluster of galaxies with GROND The galaxy population of XMMU J0338.7+0030 at z=1.1
    (2012) Pierini, D.; Suhada, R.; Fassbender, R.; Nastasi, A.; Boehringer, H.; Salvato, M.; Pratt, G. W.; Lerchster, M.; Rosati, P.; Santos, J. S.; de Hoon, A.; Kohnert, J.; Lamer, G.; Mohr, J. J.; Muehlegger, M.; Quintana, H.; Schwope, A.; Biffi, V.; Chon, G.; Giodini, S.; Koppenhoefer, J.; Verdugo, M.; Ziparo, F.; Afonso, P. M. J.; Clemens, C.; Greiner, J.; Kruehler, T.; Yoldas, A. Kuepcue; Olivares E, F.; Rossi, A.; Yoldas, A.
    Context. The XMM-Newton Distant Cluster Project is a serendipitous survey for clusters of galaxies at redshifts z >= 0.8 based on deep archival XMM-Newton observations. X-ray sources identified as extended are screened against existing optical all-sky surveys for galaxies, in case of candidate high-z clusters followed up with imaging at 4 m-class telescopes and, ultimately, multi-object spectroscopy at 8 m-class telescopes. Low-significance candidate high-z clusters are followed up with the seven-channel imager GROND (Gamma-Ray Burst Optical and Near-Infrared Detector) that is mounted at a 2 m-class telescope. Its unique capability of simultaneous imaging in the g', r', i', z', J, H, Ks bands enables the use of the photometric redshift technique.
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    Kinematic analysis of a sample of X-ray luminous distant galaxy clusters The Lx-σv relation in the z > 0.6 universe
    (2014) Nastasi, A.; Boehringer, H.; Fassbender, R.; De Hoon, A.; Lamer, G.; Mohr, J. J.; Padilla, N.; Pratt, G. W.; Quintana, H.; Rosati, P.; Santos, J. S.; Schwope, A. D.; Suhada, R.; Verdugo, M.
    Aims. Observations and cosmological simulations show galaxy clusters as a family of nearly self-similar objects with properties that can be described by scaling relations as a function of mass and time. Here we study the scaling relations between the galaxy velocity dispersion (sigma(v)) and X-ray quantities, such as X-ray bolometric luminosity (L-X,500(Bol)) and temperature (T-X) in galaxy clusters at high redshifts (0.64 <= z <= 1.46). We also compare our results with the analogous study of the local HIFLUGCS sample.