Cluster detection from surface-brightness fluctuations in SDSS data

Galaxy clusters can be detected as surface brightness enhancements in smoothed optical surveys. This method does not require individual galaxies to be identiable, and enables clusters to be detected out to surpris- ingly high redshifts, as recently demonstrated by the Las Campanas Distant Cluster Survey (LCDCS). Here, we investigate redshift limits for cluster detection in the Sloan Digital Sky Survey (SDSS). Calibrating assumptions about the surface brightness prole, the mass-to-light ratio, and the spectral energy distribution of galaxy clusters using available observational data, we show that it should be possible to detect galaxy groups out to redshifts of 0.5, and massive galaxy clusters out to redshifts of1:2 in summed r 0 +i 0 +z 0 SDSS data. Redshift estimates can be derived from the SDSS magnitudes of brightest cluster members out to redshifts near unity. Over the area of sky it covers, SDSS should nd >98% of the clusters detectable by the Planck satellite through the thermal Sunyaev-Zel'dovich eect. The few Planck clusters not detected in SDSS will almost all be at z > 1:2.