2010A&A...514L...3S

We report on the discovery of two galaxy clusters, SPT-CL J2332-5358 and SPT-CL J2342-5411, in X-rays. These clusters were also independently detected through their Sunyaev-Zel'dovich effect by the South Pole Telescope, and in the optical band by the Southern Cosmology Survey. They are thus the first clusters detected under survey conditions by all major cluster search approaches. The X-ray detection is made within the frame of the XMM-BCS cluster survey utilizing a novel XMM-Newton mosaic-mode of observations. The present study makes the first scientific use of this operation mode. We estimate the X-ray spectroscopic temperature of SPT-CL J2332-5358 (at redshift z=0.32) to be T=9.3^+3.3_–1.9 keV, implying a high mass, M₅₀₀=8.8±3.8x10¹⁴M_☉. For SPT-CL J2342-5411, at z=1.08, the available X-ray data do not allow us to directly estimate the temperature with good confidence. However, using our measured luminosity and scaling relations we estimate that T=4.5±1.3keV and M₅₀₀=1.9±0.8x10¹⁴M_☉. We find a good agreement between the X-ray masses and those estimated from the Sunyaev-Zel'dovich effect.