A Subaru weak-lensing survey. I. Cluster candidates and spectroscopic verification

We present the results of an ongoing weak-lensing survey conducted with the Subaru Telescope whose initial goal is to locate and study the distribution of shear-selected structures, or halos. Using a Suprime-Cam imaging survey spanning 21.82 deg(2), we present a catalog of 100 candidate halos located from lensing-convergence maps. Our sample is reliably drawn from that subset of our survey area (totaling 16.72 deg(2)) uncontaminated by bright stars and edge effects and is limited at a convergence signal-to-noise ratio of 3.69. To validate the sample, detailed spectroscopic measures have been made for 26 candidates using the Subaru multiobject spectrograph, FOCAS. All are confirmed as clusters of galaxies, but two arise as the superposition of multiple clusters viewed along the line of sight. Including data available in the literature and an ongoing Keck spectroscopic campaign, a total of 41 halos now have reliable redshifts. For one of our survey fields, the XMM-LSS field, we compare our lensing-selected halo catalog with its X-ray equivalent. Of 15 halos detected in the XMM-LSS field, 10 match published X-rayYselected clusters, and a further two are newly detected and spectroscopically confirmed in this work. Although three halos have not yet been confirmed, the high success rate within the XMM-LSS field (12/15) confirms that weak lensing provides a reliable method for constructing cluster catalogs, irrespective of the nature of the constituent galaxies or the intracluster medium.