Key points are not available for this paper at this time.
The Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) is a deep z'-band imaging survey covering the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) Legacy fields designed to create the first large homogeneously selected sample of massive clusters at z > 1 using an infrared adaptation of the cluster red-sequence method. We present an overview of the northern component of the survey which has been observed with Canada-France-Hawaii Telescope (CFHT) /MegaCam and covers 28. 3 deg². The southern component of the survey was observed with Cerro Tololo Inter-American Observatory (CTIO) /MOSAICII, covers 13. 6 deg², and is summarized in a companion paper by Wilson et al. We also present spectroscopic confirmation of two rich cluster candidates at z ~ 1. 2. Based on Nod-and-Shuffle spectroscopy from GMOS-N on Gemini, there are 17 and 28 confirmed cluster members in SpARCS J163435+402151 and SpARCS J163852+403843 which have spectroscopic redshifts of 1. 1798 and 1. 1963, respectively. The clusters have velocity dispersions of 490 ± 140 km s^ (–1) and 650 ± 160 km s^ (–1), respectively, which imply masses (M_ (200) ) of (1. 0 ± 0. 9) × 10^ (14) M_⊙ and (2. 4 ± 1. 8) × 10^ (14) M_⊙. Confirmation of these candidates as bonafide massive clusters demonstrates that two-filter imaging is an effective, yet observationally efficient, method for selecting clusters at z > 1.
Muzzin et al. (2009) studied this question.